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SID 5 Research Project Final Report

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NoteIn line with the Freedom of Information Act 2000, Defra aims to place the results of its completed research projects in the public domain wherever possible. The SID 5 (Research Project Final Report) is designed to capture the information on the results and outputs of Defra-funded research in a format that is easily publishable through the Defra website. A SID 5 must be completed for all projects.

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Project identification

1. Defra Project code WU0102

2. Project title

A study to identify baseline data on water use in agriculture

3. Contractororganisation(s)

ADAS UK lydWoodthorneWergs RoadWolverhamptonWest MidlandsWV6 8TQ

54. Total Defra project costs £ 28741

5. Project: start date................ 22 May 2006

end date................. 30 September 2006

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6. It is Defra’s intention to publish this form. Please confirm your agreement to do so...................................................................................YES NO (a) When preparing SID 5s contractors should bear in mind that Defra intends that they be made public. They

should be written in a clear and concise manner and represent a full account of the research project which someone not closely associated with the project can follow.Defra recognises that in a small minority of cases there may be information, such as intellectual property or commercially confidential data, used in or generated by the research project, which should not be disclosed. In these cases, such information should be detailed in a separate annex (not to be published) so that the SID 5 can be placed in the public domain. Where it is impossible to complete the Final Report without including references to any sensitive or confidential data, the information should be included and section (b) completed. NB: only in exceptional circumstances will Defra expect contractors to give a "No" answer.In all cases, reasons for withholding information must be fully in line with exemptions under the Environmental Information Regulations or the Freedom of Information Act 2000.

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Executive Summary7. The executive summary must not exceed 2 sides in total of A4 and should be understandable to the

intelligent non-scientist. It should cover the main objectives, methods and findings of the research, together with any other significant events and options for new work.

Water Use in Agriculture: Establishing a Baseline

The total on-farm use of abstracted water is estimated to be in excess of 300 million cubic metres a year.

Within this total, approaching half (128 M m3) is reliably estimated to be used for the irrigation of field crops during the summer months only (June to August inclusive). Of this irrigation water, 75 M m3 is used on the potato crop (5 M m3 on early varieties and 70 M m3 on maincrop), and a further 34 M m3 on field vegetables. In both sectors the primary reason for irrigation is to ensure quality of product rather than maximise yield, as irrigation is employed only when there has been insufficient rainfall during the main growth period (also for establishment for some vegetables). An increasing proportion, though still <10%, of irrigation is by trickle irrigation methods.

Field crop irrigation is carried out predominantly in eastern and southern regions of England, and almost not at all in Wales. Eastern England is the most prolific user, accounting for more than 45 M m3 annually, followed by the East Midlands at 29 M m3 and the South East at 22 M m3. Trickle irrigation is practised most in the South East where more than half of the national estimate is used.

This distribution of irrigation use corresponds with the areas of high insolation and least summer rainfall. Climate change is predicted to increase demand for irrigation most in these regions, by about 20% by 2020 and 30% by 2050, at the same time as reducing summer rainfall. Demand is also concentrated on lighter soils, sands and sandy loams, in the above regions.

Livestock rearing is estimated to account for another 119 M m3 of water used on farms. This is mainly for consumption (drinking), but also for cleaning housing and yard assembly areas. The cattle sector is the biggest user, accounting for 82 M m3 of use, followed by sheep at 17 M m3, Poultry at 12 M m3 and pigs at 8 M m3. Within the cattle sector, the dairy industry uses the most water, as a dairy cow requires about 33,000 L of drinking water a year compared with about 7,000 L for a beef cattle. Livestock use is fairly evenly distributed throughout the year, with a small increase during the summer

Water use by cattle is heavily biased towards western regions, with 28, 16 and 12 M m3 used in the South West, North West and West Midlands regions, respectively. Sheep are also concentrated in the west, where most land is under pasture, with 3.6 and 3.2 M m3 of water used in their rearing in the South West and North West regions, respectively. Pigs and poultry are more evenly spread across the country, but with concentrations of pigs occurring in Yorkshire and Humberside (2.4 M m3 used)

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and Eastern England (2.2 M m3 used), and poultry in Eastern England (3 M m3 used) and East Midlands (2 M m3 used).

The third largest sector in terms of overall water use is the protected and nursery crops sector, accounting for about 53 M m3 of water annually. This is mainly concentrated in the South East of England, but with significant use in the Midlands and Eastern England and with a presence in all regions.

A more minor, but still significant use of water is in spraying pesticides on field crops, which accounts for nearly 3 M m3 nationally, and is proportional to the amount of arable cropping in a region. For this reason, most use is therefore found in Eastern England (0.8 M m3) and the East Midlands (0.5 M m3).

Vegetable and potato washing, and the use of water for glasshouse, protected and nursery crops amounts to less than 0.3 M m3 nationally.

Overall across England, agriculture uses most water in the regions which are least capable of supplying it : Eastern England > East Midlands > South West > South East > West Midlands > North West > Yorkshire & Humberside > North East. In addition this supply is demanded during the driest part of the year and is abstracted almost equally from ground and surface water sources.

Because of the importance of irrigation as the largest user of water by agriculture, it is recommended that the occasional voluntary survey of use is pursued more robustly in future at periodic intervals. In addition, the possibility of linking it with the National Abstraction Licensing Database held by EA should be considered.

The periodic (bi-annual) survey of pesticide use proves useful to assess water use by spraying programmes, and extending this to cover field horticultural crops should be considered. It may also be worthwhile collecting data on volumes of water used in spraying more overtly within the survey.

The usage by livestock is estimated from assessments of water use per livestock unit, and numbers of animals recorded in the national census each year. A more secure estimate of use could potentially be collected from the records of individual farmers, which often include the cost to water supply, and this should be considered.

Similarly, because water is a significant cost to protected crop production, and for salad crops at least has to be from potable public water supplies for health reasons, then its use is metered by growers and they will keep accurate records of their overall consumption. This data could be accessed by a more formal and structured monitoring exercise (census or survey). This could be a cost-effective approach for such a high volume user with potential savings to be made (possibly through greater use of roof collections and re-use).

Project Report to Defra8. As a guide this report should be no longer than 20 sides of A4. This report is to provide Defra with

details of the outputs of the research project for internal purposes; to meet the terms of the contract; and to allow Defra to publish details of the outputs to meet Environmental Information Regulation or Freedom of Information obligations. This short report to Defra does not preclude contractors from also seeking to publish a full, formal scientific report/paper in an appropriate scientific or other journal/publication. Indeed, Defra actively encourages such publications as part of the contract terms. The report to Defra should include: the scientific objectives as set out in the contract; the extent to which the objectives set out in the contract have been met; details of methods used and the results obtained, including statistical analysis (if appropriate); a discussion of the results and their reliability; the main implications of the findings; possible future work; and any action resulting from the research (e.g. IP, Knowledge Transfer).

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Report for Defra Project WU0102

Water Use in Agriculture: Establishing a Baseline

John King, ADAS BoxworthDon Tiffin, ADAS Boxworth

Dan Drakes, ADAS BoxworthKen Smith ADAS Wolverhampton

With a contribution from Dr Keith Weatherhead, Cranfield University , Beds.

October 2006

1 INTRODUCTION

There is a current need to more firmly establish the overall net water usage by agriculture. This is chiefly for two reasons: Recent changes in Government administrative structures mean that data gathering on water use is no longer

carried out, its location is unclear, or its format is unsuited to present policy-making. The climate is changing, and recent fluctuations of weather patterns have made it clear that adequate water

provision can no longer be taken for granted.These two reasons should be set against the continuing increase in demand for water by domestic and industrial users, and that agricultural water use will have to become a more closely regulated part of an overarching water supply policy.

This report, therefore, seeks to provide an overview of the water use throughout agriculture by sector, sub-sector and region from the currently accessible sources of such data. In doing so it will also identify gaps in the information provision, and offer advice on how data collection and dissemination may be better facilitated in the future.

2 AIMS AND OBJECTIVES

The overall aim of this work was to provide information to allow Defra to establish how and where water is used in agriculture and horticulture. The extent of this work covered agricultural and horticultural water use up to the point that produce leaves the farm gate. Water use covered both abstracted and piped water and identified the sectors and sub-sectors that are the heaviest users of water. Where possible, regional variations in water were identified.

The specific objectives of this project were:

A desk-based study to identify and assess existing information on water use in different sectors and sub-sectors of agriculture and horticulture;

A more detailed review of existing information to analyse, refine and present data on water use in agriculture and horticulture;

A report describing the information available and the current knowledge gaps relating to water use in agriculture and horticulture.

These objectives were met within a structure that takes each agricultural sector in turn, and concludes with an overarching view of agriculture and recommendations for future data gathering. This structure is as follows:

Field crops Irrigation Spraying and washing-out of equipment. Washing of produce on farm.

Protected cropping Irrigation (protected glasshouse crops) Irrigation (other protected crops) Washing of protected and horticultural crops.

Livestock farming; Dairy and beef cattle Sheep production Pig production Poultry industry

The report is rounded off with comments on sources of water used on farms, an overall appreciation of the regional distribution of water use, and some consideration of the quality of the information available and recommendations for improved data gathering and collation in future.

3 RESULTS AND DISCUSSION

3.1 Field crops3.1.1 Irrigation (nationally by crop category)There are two sets of data relevant to understanding the irrigation requirements for England:1. the amount of water that is licensed to be abstracted for irrigation purposes 2. the actual amount used for irrigation of crops

The two amounts are considerably different. The amount of licensed abstraction is governed by the Environment Agency and will be dealt with below under the heading “Sources of water for on-farm use.”

The data discussed in this section is the actual amount used by on-farm irrigation activity, or at least estimates of this based on smaller-scale measurements. National statistics have been based upon surveys carried out by MAFF between 1963 and 1995, and one survey since then for Defra carried out by Cranfield University. These surveys (1963 – 1995) were voluntary and based upon a “trigger question” in the Census of Agriculture carried out every June. They were biennial until 1977 (with the unspecified omission of 1969), but high workloads meant that this regularity could not be adhered to, and are best described as conducted every 2-3 years subsequent to this date. Following the Strutt Report of 1980 (Strutt, 1980) which recommended an improvement to the accuracy of data collection for planning purposes, the questionnaire was revised in 1982 and this format held until the last one collected by MAFF in 1995. At that time it was decided to only survey in “dry years” though at MAFF’s discretion, so not necessarily every dry year. In addition, Wales has not been covered since the early 1990s, when it was decided that the volume was insignificant (in 1992 the area irrigated in Wales was only 1.4% of that in England and Wales (0.8% by volume); MAFF, 1997). Since 1995, only one survey has been conducted (in 2001), by Cranfield University on behalf of Defra, using the same basic format as before (Weatherhead & Danert, 2002).

The format of the recent surveys was to collect statistics for each of the main irrigated crop categories given in the following sections, by both area irrigated and volume of water used. They also recorded the source of the water used (by volume), which is dealt with in a later section, and the type of irrigation and method of scheduling as an overall proportion. For comparison, the latest estimates in Weatherhead & Danert (2002) are displayed alongside the previous survey results for years; 1982, 1984, 1987, 1990, 1992 & 1995. Previous records are available and some of them feature in the Strutt report of 1980, especially 1972, 1974 and 1977, but follow a slightly different format and must surely be considered of only historic interest now. The 2001 survey was based on a questionnaire that was sent to 5603 holdings in England that had responded in the June 2000 census as being “able to irrigate”. Of these, 41% responded, representing 55% of the area reported as irrigated. This response compares with a response rate of 78% for the 1995 questionnaire sent to 7800 holdings in England (previous surveys also included Wales)(Stansfield, pers. comm.). In both cases, and in previous years, the results have been adjusted to account for this pro rata response rate, and reflect the estimated amounts for the whole area irrigated, and as such are subject to some degree of error.

3.1.1.1 Irrigation usage by cropTables 1 and 2 are reproduced from Weatherhead & Danert (2002) and show the estimated irrigation water usage by crop for areas irrigated (Table 1) and volumes of water used (Table 2), for the last seven surveys across England (all) and Wales (up to 1992).

Table 1 Area of irrigated outdoor crops (ha) in England and Wales (1995 & 2001 England only).

Crop category Year1982 1984 1987 1990 1992 1995 2001

Early potatoes (before 31st July)

8,050 7,720 5,360 8,510 8,180 8,730 7,300

Maincrop potatoes (after 31st July)

22,810 34,610 29,520 43,490 45,290 53,390 69,820

Sugar beet 15,770 25,500 10,100 27,710 10,520 26,820 9,760

Vegetables 14,810 17,460 11,040 25,250 20,200 27,300 39,180

Small fruit (soft fruit)

3,610 3,560 2,230 3,470 2,750 3,250 3,770

Orchard fruit 3,100 3,250 1,330 3,320 2,280 2,910 1,580

Grass 16,440 18,940 6,970 15,970 7,240 10,690 3,970Cereals 14,800 24,700 7,510 28,100 7,160 13,440 4,620

Other outdoor crops and trees

4,100 4,890 2,440 8,650 4,320 9,120 7,280

Total 103,490 140,630 76,500 164,470 107,940 155,650 147,280

Farmers irrigate crops for both quantity and quality reasons; mainly to improve the saleable yield, its quality, and continuity and reliability of supply. They also irrigate to prevent disease (such as scab in potatoes) and aid timeliness of establishment and harvest. Irrigation in the UK is, therefore, a “supplement”, and so neither the area irrigated or amount used is directly proportional to the area of crops grown, and depends more upon the amount

of rainfall received on a season to season basis. Certain trends are evident in the data though when plotted over time by crop category as in Figure 1, the main one being the steady rise in the area of irrigated maincrop potatoes over the twenty year period. A steady increase has also been seen in the area of vegetables irrigated since the late 1980s, and these trends overlay the seasonal fluctuations that are seen most clearly in the areas of sugar beet and cereals irrigated (Figure 1). The trends between years are more clearly seen by dividing the total amounts used in Table 2 by the area in Table 1 to ascertain the changes in the amount of water used to irrigate per unit area of crop, as displayed in Figure 2. This figure shows that the amount applied peaked for all crops in the same years, namely 1984, 1990 and 1995, which suggests that these were exceptionally dry years requiring more irrigation to maintain crop quality and yield. Indeed 1990 and 1995 were deemed “dry” years (Weatherhead & Danert, 2002), but 1984 (and 1982) was considered only “average”. Rather it was the case that 1987, 1992 and 2001 were considered “wet” years, and it was the case that in 1992 heavy rain in July reduced the area of sugar beet irrigated by 40% (Stansfield, pers. comm.).

Set against this annual fluctuation in rainfall it is interesting to see a background but consistent rise in the volume of irrigation water used per unit area for “other crops”, and there also seems to be a consistent but gentle “background” rise in the amount applied to potatoes, small fruit and vegetables over the 20 year period (Figure 2).

Table 2 Volume of water used (‘000 m3) for irrigated on outdoor crops in England and Wales (1995 & 2001 England only).

Crop category Year1982 1984 1987 1990 1992 1995 2001


4,680 4,920 2,350 6,770 5,590 9,345 5,710


15,280 32,730 14,700 51,170 38,520 74,460 69,940

Sugar beet 8,260 17,370 3,430 20,320 4,860 21,295 4,630

Vegetables 6,830 11,390 4,640 18,450 12,180 25,500 34,120


1,890 2,660 970 3,180 2,000 4,320 3,370

Orchard fruit 2,180 2,430 550 2,930 1,220 2,445 900

Grass 10,030 13,550 3,550 13,100 4,280 9,920 2,320Cereals 5,040 8,300 2,160 11,830 2,260 5,625 1,470


1,020 4,030 1,270 6,040 4,160 11,160 8,840

Total 55,210 97,380 33,620 133,790 75,070 164,070 131,300

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a)

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Maincrop potatoes

Sugar beet

Vegetables


Orchard fruit

Grass

Cereals

Other outdoor cropsand trees

Figure 1 The change in area of outdoor crops irrigated (ha) in England and Wales (England only for 1995 & 2001).

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Sugar beet

Vegetables

Small fruit (softfruit)

Orchard fruit

Grass

Cereals

Other outdoorcrops and trees

Figure 2 The changes in the volume of irrigation water used annually per hectare of outdoor crops with season in England and Wales (England only for 1995 & 2001) (‘000 m3 ha-1).

3.1.1.2 Irrigation usage by regionThe results of the surveys of irrigation of outdoor crops in England and Wales did not report the regional breakdown of the statistics of water usage, although the background data was collected at the county level (Stansfield, pers. comm.). The latest survey of Weatherhead & Danert (2002) did also collect and collate information on a regional basis, and this has kindly been made available for this report (Weatherhead, pers. comm., 2006). The results for the area of crops irrigated in 2001 is therefore shown according to crop and EA region in Table 3, although data are not shown for regions with only small areas where confidentiality may be compromised. The corresponding data, given as the total amount of water used in each EA region, is shown in Table 4.

Similar regional breakdowns for the years 1982 – 1995 as shown in Tables 1 & 2 and Figures 1 & 2 are not available to the authors, though a breakdown by MAFF regions for 1972, 1974 & 1977 are given in the 1980 Strutt report (Strutt, 1980). The MAFF regions, however, do not correspond to either the EA regions shown in Tables 3 & 4 and Figure 3, nor GORs (Government Office Regions) used later in this report, and so this historic data ha not been followed up.

Table 3 shows that the Anglian region accounts for over half of the area of irrigated crops and, with the Midlands region, 73% of the area irrigated in England and Wales, and the proportions are similar by volume (71% was used in the Anglian and Midlands regions). Earlier reviews of irrigation in England and Wales (Strutt, 1980; Stansfield, pers. comm.) had predicted future irrigation needs and it is instructive to compare these with the closest actual usage value from recent surveys. Stansfield in 1997, reviewed the results of the 1995 survey and predicted future requirements (Stansfield, pers. comm.) for EA regions by adapting predicted volumes from Weatherhead et al. (1994) for 1996, 2006 & 2021, and these are compared with the volumes from Table 3 in the histograms of Figure 3.

The national totals predicted for three years from both references previously mentioned (Strutt, 1980; Stansfield, pers. comm.) are shown against the values estimated from actual surveys carried out between 1982 and 2001, in Figure 4.

Table 3 Area of irrigated outdoor crops (ha) in Environment Agency (EA) regions of England and Wales (2001 survey).

Crop category EA RegionNorth East

North West

Mid-lands

Angl-ian

Tha-mes

Sout-hern

S West

EA Wales

Wales nation

Total E&W


367 221 1,062 4,429 180 742 258 403 368 7,663


8,349 614 10,682 40,669 5,005 2,665 939 1121 224 70,045

Sugar beet 590 w 4,610 4,463 w w w w w 9,758

Vegetables 919 445 7,444 20,102 1,966 8,084 165 w w 39,179


w w 654 1,502 329 824 309 w w 3,776

Orchard fruit w w 276 510 w 710 w w w 1,580

Grass 422 w 705 1,670 175 836 w 150 150 4,119Cereals w w 1,218 3,171 w w w w w 4,616


148 193 1,362 3,751 676 843 301 w w 7,286

Total 10,941 1,580 28,021 80,260 8,333 14,817 2,126 1,944 749 148,022W = indicates that values have been withheld to protect confidentiality (values are included in totals though)

To some degree, it is inevitable that actual usage of irrigation water will be less than that predicted because, by its nature, prediction modelling has to accommodate the requirements that may be needed in dry years, and cannot anticipate the actual future rainfall. Certainly, the Strutt report suggested that its projections should be considered as an upper limit (Strutt, 1980) and based them on the needs of the 5th driest year in 20. They also incorporated opinion about changes in the structure of the agricultural industry, and general economics, but assumed that the relative economics between crop commodities would not change, nor that the technology or relative costs of irrigation would change either. The fact that actual usage in 1995 & 2001 is so far below the volumes predicted in 1980 may be partially explained by the fact that assumed increases in the area of early potatoes and vegetables that would be irrigated by 2000, were not realised. Strutt (1980) projected that 16,000 ha of early potatoes and 55,000 ha of vegetables would be irrigated by 2000, which are far in excess of the 7-8,000 and 39,000 ha estimated in the 2001 survey (Table 1). In addition, they assumed 55,000 ha of sugar beet would be irrigated whereas the area has fallen drastically in recent years and less than 10,000 ha were actually irrigated in 2001. The error then is due to over-ambitious expectations of the market and grower habits rather than any perceived changes in the environment, because one thing that was not taken into account then was the potential for climate change, being a largely unrecognised phenomenon at that time.

In a fuller exploration of future irrigation needs, Weatherhead & Knox (2000) compared four models (including that used to produce the 1994 line in Figure 4) and incorporated them into recently developed GIS approaches (Knox et al., 1997) to improve predictions of the spatial future demand for irrigation water that may be experienced. They also displayed data that compared actual usage with predicted dry year demand that was not dissimilar to that in Figure 4 but went on to re-model future requirements based on changes in agriculture predicted by the Manchester University Agricultural Policy model (Burton, 1992). The result was a rise from just under 200 M m3

nationally in 2001 to about 250 M m3 by 2021, but with a strong rise in requirements in lighter soil areas throughout the Anglian region, the sandlands of east Nottinghamshire in the East Midlands region and some areas of sandy soils in Shropshire in the West Midlands near the Welsh border (Weatherhead & Knox, 2000). These are probably the best available prediction for future irrigation requirements in the UK and readers are directed to the above paper for a full exposition of this topic.

Table 4 Volume of water used for irrigation on outdoor crops (‘000 m3) in Environment Agency (EA) regions of England and Wales (2001 survey).

Crop category EA RegionNorth East

North West

Mid-lands

Angl-ian

Tha-mes

Sout-hern

S West

EA Wales

Wales nation

Total E&W


263 78 925 3,645 132 549 97 185 167 5,874


6,813 343 10,874 39,745 8,101 2,585 794 820 133 70,076

Sugar beet 313 w 2,649 1,601 w w 70 w w 4,635

Vegetables 708 177 8,315 16,967 1,487 6,360 95 w w 34,123


w w 430 1,462 182 773 386 w w 3,367

Orchard fruit w w 109 384 w 337 w w w 897

Grass 300 w 267 1,015 287 337 w 152 152 2,471Cereals w w 436 953 w w w w w 1471


430 201 1,477 3,090 2,351 1,028 243 w w 8,843

Total 8,893 914 25,478 68,822 12,565 12,024 1,698 1,362 459 131,756W = indicates that values have been withheld to protect confidentiality (values are included in totals though)

The predictions of change upon which Figures 3 and 4 are based are taken entirely from changes in the agricultural industry (changes in markets, demand and quality requirements) and annual increases range from 1.7 to 2.5% for the period 1996-2001 (Weatherhead et al. (1994) and Weatherhead & Knox (2000), respectively), and estimated increases for the period 2001-2021 were 1 to 1.5% in the same references (for design “dry” years). Neither sets of predictions took climate change into account, but Weatherhead & Knox (2000) did point out that there will inevitably be an increase in soil moisture deficits, especially in the drier eastern regions of England, if the UKCIP02 scenarios are realised and summer rainfall decreases in these regions (Hume et al., 2002). Downing et al. (2003) specifically examined the potential impact of climate change on the demand for water, and came to the conclusion that climate change would increase irrigation usage by around 20% by the 2020s and 30% by the 2050s.

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North East NorthWest

Midlands Anglian Thames Southern SouthWest

Wales TotalE&W

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rigat

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wat

er ('

000m

3)

Figure 3 The estimated volumes of irrigation water used per EA region in 2001 (black histograms) (Weatherhead & Danert, 2002), compared with predicted volumes for 1990 (white histograms), 2006 (light grey histograms) and 2021 (dark grey histograms) (Weatherhead et al., 1994).

These increases would be highly regional ranging from an extra 24-25% in the Thames region (EA region) to a 4% decrease in the North West. In addition, Downing et al. (2003) point out that there will be regional shifts in

cropping pattern and agro-climatic zones will move northwards and westwards. By the 2020s, central England will experience conditions similar to those currently typical of eastern England and, by the 2050s, irrigation needs in the eastern, southern and central regions will be greater than anywhere currently experienced in the UK.

3.1.2 Spraying and washing-out of equipmentOutside of the organic farming sector, all arable crops require considerable amounts of water to be applied to them for the delivery of various pesticides by spray application. The range and amounts of the various pesticide products used in the UK is monitored at frequent intervals (bi-annually) by Defra, which records their usage on all field crops and ancillary statistics about how they are administered, dose rates, timing, number of applications, etc. Amongst these statistics are also recorded the average number of spray applications for each category of pesticide used and the typical volumes sprayed.

The most recent two records of these statistics have been cited here to give an estimate of current usage of water in spray applications in Tables 5 and 6 for the spray applications in 2002 (Garthwaite et al., 2003) and 2004 (Garthwaite et al., 2005), respectively. For the information in Tables 5 and 6, an overall average spray volume for each crop was calculated from the frequencies used over a range of volumes given in the reports, and the average number of spray events for each crop, also recorded in the reports. The overall volume of water used in both years is remarkably consistent at between 2.8 and 2.9 M m3, which suggests that these values are indeed a reliable baseline for current water usage.

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1970 1980 1990 2000 2010 2020 2030

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me

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(Mm

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Actualsurveyed

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Linear(Predicted1977 (S))

Linear(Predicted1996 (W))

Figure 4 The estimated volumes of water used throughout England and Wales between 1982 and 2001 (open black squares) compared with the trend in requirements predicted in 1977 (Strutt, 1980) (blue lozenges) and trend predicted in 1994 (Weatherhead et al., 1994) (red triangles).

The volumes of water used for each crop category in 2004 are also shown in Figure 5, which highlights the fact that wheat (both winter and spring wheat) accounts for about half of all pesticide sprays in England and Wales. The exact distribution by crop varies as the area of crops grown varies annually according to the market and weather factors, but is basically similar for both the years shown in Tables 5 and 6. In both these years, the other crops that used appreciable volumes of water in their spray regimes were oilseed rape, winter barley and ware-potatoes.

When considering the regional distribution of water use by pesticide spraying, the picture is a little unclear because the two most recent years were recorded against different regional definitions. Up to the 2002 survey (Garthwaite et al., 2003), statistics were recorded by regions that followed the boundaries of the old MAFF agricultural regions, which comprised the five regions in England shown in Table 5 and Wales. However, the survey for 2004 (Garthwaite et al., 2005) recorded data according to the Government Office Regions (GOR) which are more widely used now for most Government policy applications. There are nine of these in England (London is usually a separate region in its own right) and Wales constitutes the tenth, as in the heading to Table 6. It is difficult, therefore, to carry out a straightforward comparison of the regional distribution of water use between these years, but the clear eastern bias is shown in both Tables 5 and 6, where the greatest usage is in

the regions where arable agriculture is practised most. These are the Eastern MAFF region of Table 5, and the Eastern and East Midlands regions of Table 6 and Figure 6, where the Eastern region constitutes what is more colloquially called East Anglia. Other regions with appreciable usage are also those with sizeable areas of wheat and rape, such as the South East, and potatoes, such as Yorkshire and Humber and the West Midlands (Figure 6). Scotland was also included in the Pesticide Usage Surveys, but has not been included in this report.

Omitted from the Defra reports on spraying practice (Garthwaite et al, 2003 & 2005) are statistics for the amount and type of pesticide sprays for field vegetable crops. These are of a similar area to potatoes in England and Wales (145,000 ha compared with 149,000 ha) with overall a similar number of spray applications (more for some crops, but less for others). Based on these assumptions, an estimate has been made on the overall volumes of water used to spray field vegetable crops (D. Tiffin, ADAS consultant, pers. comm.), and this has been included as an extra line for 2004 data in Table 6 (in parenthesis).

Table 5 The volume of water used in 2002 (‘000 m3) for the spraying of crop pesticides (all) in the crop categories shown throughout England and Wales. Volumes are also shown by region (historic MAFF regions).

Crop MAFF region Total Northern Midlands

and Western

Eastern South Eastern

South Western

Wales England and

WalesWheat (all) 244 230 609 196 147 12 1,437W. Barley 73 55 91 27 38 6 291S. Barley 25 16 28 15 21 6 111Oats (all) 6 14 7 13 12 2 54Rye 0 0 2 0 0 0 3Triticale 1 1 1 1 2 0 5Oilseed rape (all) 37 34 81 35 17 1 205Linseed (all) 0 1 1 1 2 0 5Potatoes (ware) 43 61 107 10 16 5 241Potatoes (seed) 2 0 1 0 0 0 3Peas 8 9 27 15 8 0 67Beans (all) 11 20 45 15 11 1 103Sugar beet 18 19 96 0 1 0 133Set aside 31 29 66 30 23 1 180

All arable 498 489 1,161 359 298 35 2,840

0

200

400

600

800

1000

1200

1400

1600

Whe

at (al

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W. B

arley

S. Barl

ey

Oats (a

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Tritica

le

Oilsee

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e (all

)

Linse

ed (a

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Potatoe

s (war

e)

Potatoe

s (se

ed)

Peas

Beans

(all)

Sugar

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Set as

ide

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wat

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Figure 5 The volumes of water used in 2004 (‘000 m3) for the spraying of crop pesticides (all) in the crop categories shown throughout England and Wales.

Figure 6 The volumes of water used in 2004 (‘000 m3) for the spraying of crop pesticides (all) in the GOR regions of England and Wales.

Table 6 The volume of water used in 2004 (‘000 m3) for the spraying of crop pesticides (all) in the crop categories shown throughout England and Wales. Volumes are also shown by region (Government Office Regions (GOR)). Volumes for horticultural field vegetables are estimates based on area of crop and spray programme (D. Tiffin, ADAS, pers. comm.), as they are not included in the Defra reports (Garthwaite et al., 2005).

Crop GOR Total East Mids

Eastern London & South

East

North East

North West

South West

West Mids

Yorks & Humbs

Wales England & Wales

Wheat (all) 300 399 196 55 28 149 130 196 12 1,464W. Barley 30 53 20 16 10 29 20 41 5 223S. Barley 12 26 15 6 10 25 9 18 6 127Oats (all) 4 3 8 2 2 8 7 2 2 38Rye 1 2 1 0 0 0 0 0 0 5Triticale 0 1 0 0 0 2 1 0 0 5Oilseed rape (all)

72 61 55 17 3 32 24 44 2 311

Linseed (all) 3 3 4 0 0 4 1 1 0 16Potatoes (ware)

42 92 10 4 18 15 41 41 5 267

Potatoes (seed)

0 1 0 0 0 1 1 2 0 5

Peas 13 18 8 0 0 4 3 5 0 52Beans (all) 25 47 21 2 2 13 11 9 1 132Sugar beet 23 60 0 0 0 0 10 15 0 108Set aside 26 34 25 6 3 19 12 15 1 141Vegetables 40 89 10 8 9 13 14 15 0 198All arable 591 889 373 116 84 314 283 405 36 3,093

3.1.3 Washing of produce on farmAfter harvesting, vegetable crops need to be prepared for sale either to wholesale markets or multiple retailers, for further market preparation such as processing (canning and freezing) or to food factories. For many crops, this market preparation includes washing and, therefore, the efficient and cost effective use of water.

The reasons for washing vegetable crops are to remove unwanted material such as soil, to improve the appearance and possibly to remove pesticides. Water is also used to cushion/move crops though other

processes such as size grading and ‘polishing’. Crop washing may take place in the field or in a packhouse or a combination of both. The scale of production will have an influence as will the tenderness or perishability of the crop and the quantities to be washed.

Crops tend to be transported to a packhouse for large-scale operations and demanding markets where special operations such as ‘carrot polishing’ are required. Another advantage (over field preparation) is that market preparation can be continuous over 24 hours regardless of the weather. The major crops where washing takes place, on farm in a packhouse, are the large scale root crops: potato, carrot, parsnip and swede but also minor root crops such as turnip, beetroot, radish and celeriac.

In field selection, washing and packing takes place for some leeks, celery and salad onions though the harvesting and market preparation operation may be split between field work and packhouse work as detailed in the individual crop comments. The few small scale crisping potato growers tend to rely on rented mobile washers, which are carted from farm to farm on a lorry, with washing taking place at the home farm. Minor crops such as pumpkins may be washed in the field and some asparagus is washed and cooled.

Further processing, including washing, may take place in the preparation of prepared potato and vegetable products and of baby-leaf and mixed leaves for salad packs but this is considered to be carried out post ‘farm-gate’ often in purpose-built industrial premises, i.e. a food factory.

3.1.3.1 Washing of root vegetable cropsThis includes carrot, parsnip and swede and minor root crops such as beetroot, radish, turnip and celeriac. Systems and procedures for washing root vegetables tend to be custom-designed using specialist equipment and procedures to take account of: crop(s) to be washed market requirement/outlet. scale of operation, soil type (e.g. less water required for crops grown on sands than those on heavier clay soils) necessity for water re-circulation No two washing systems are the same, though the objective is of course the same i.e. to provide a clean marketable product to the next stage of the supply chain.

There are a number of stages in the washing of root vegetable crops, though not all stages will apply to every crop. The differences are noted in the comments for individual crops. dry soil removal dumping into the packhouse stone separation barrel washing brush washing vegetable polishing cooling final rinsing.

At all stages, handling must be minimised and movement of product should always be in one direction without crossovers. Increasingly, water (often under pressure) is used to move the crop from one stage to the next. This technique minimises damage such as bruising (in parsnips) and breaks and splits (particularly in carrots).

Carrots and Parsnips

The crop is mostly fresh washed as required for production and sales. It is essential that the washing area allows an efficient and rapid throughput of raw material in order to maintain quality in the final product. The washing area must be separated from the packing area so that clean and dirty areas are distinct.

All carrot washing lines are custom designed to minimise crop damage, to obtain ease of cleaning and for water minimisation. An in-line hydro-cooler will remove much of the field heat and assist in the preservation of freshness and shelf life. Potable water is introduced at hydro-cooling, often each day though some producers only change water every 2 to 3 days and use chlorine to maintain water quality. Hydro-coolers have a capacity of up to 32 m3 water, which is re-circulated to the cruder/dirtier stages of the washing process.

The biggest change for carrots and parsnips has been the introduction of vegetable polishers which have improved the appearance of the marketed crop and increased the percentage marketable by removing surface blemishes caused by ‘silvering’ or diseases such as scab or cavity spot. However this equipment uses more water as there is a sprinkler bar continuously running and the water has to be replenished more often because of the accumulation of carrot tissue removed in the washing/polishing process. Also there has been a switch to

baby Chantenay type carrots which means that more soil arrives (up to 10% by weight rather than 3%) and this needs to be removed, ideally whilst the crop is still ‘dry’.

Turnips and Swedes

For turnips, only a barrel washer with jets over the brushes is required for market preparation because much of the crop is grown on fine sands with very little soil adhering to the roots. Hydro-cooling is used to remove field heat and maintain the turgidity of the roots. Water for washing is introduced each day at the hydro-cooling stage with the source often being from a borehole. After washing, water is filtered into a lagoon and subsequently discharged.

For swedes, all the stages outlined for carrots and parsnips above would be adopted by most growers, apart from the vegetable polishing and hydro-cooling stages. Cooling of swedes is by forced air as the more expensive alternative of hydro-cooling is not required.

Beetroot

The need for washing depends on the soil type the crop is grown in, and on the market outlet. For example, crops grown on fen peat soils will pass through a cyclone washer before being topped and tailed, graded and stored but crops grown in the Isle of Axholme area are not washed as virtually no soil adheres to the roots and any that does will be removed when the crop goes for processing.

Radishes

Freshly harvested radishes are placed in a ‘soak tank’" immediately on reaching the packhouse and then on to final washing and rinsing. The washing line should be capable of handling a rapid throughput. The water used for final rinse must be of a potable standard and will be re-circulated to the soak tank.

Minor Root Vegetables (Celeriac, Kohl Rabi, etc.)

Water use is generally very small for crops such as kohl rabi, which has a smooth surface with minimal soil adhering. However, extensive washing is required for celeriac because of the nature of the surface of the root. The wash water is recycled for the duration of the day, ending with a final rinse through fresh mains water. Any effluent from the process is pumped into a sedimentation lagoon before discharge.

3.1.3.2 Washing of other vegetable cropsLeeks

Washing and market preparation takes place in the field on purpose-built rigs, though this may be supplemented by further washing in a packhouse. On the rigs there is a tank wash and final rinse wash using potable water, which is recycled throughout the day. The final rinse water tops up the tank water as it becomes dirty, which depends on the soil type and time of year the crop is being harvested.

Pre-pack leeks may be trimmed (with rotary cutting head or air knives) from the rig, jet washed and drained in a packhouse. Again, recycled potable water is used. Loose leeks from the field rigs may receive a hand help lance wash before packing.

Salad onions

Systems vary but usually the crop is bunched in the field and taken to a packhouse to be trimmed, washed and drained. The volume of water used depends on the amount of soil/dirt on the crop, i.e. when the soil is wet in the winter there is more to wash off and conversely in the summer, when the soil is dry, there is less soil adhering to the onions. Dirty water containing soil and crop debris, including the cut off tops of the onions, is pumped out into a holding pit where it falls through a screen that removes the solids. The water is then channelled back into a holding tank where the screened particles (soil, etc.) settle to the bottom and the water is re-circulated.

Celery

The majority of the crop is cut, selected, trimmed, rinsed, sleeved and packed to multiple specification in the field on purpose-built mobile packhouses or ‘rigs’ that have a water tank of c. 5000 L. Mains water, chilled to 3oC, is used and it is recycled throughout the day. The amount of water used per tonne is minimal but it does depend on amount of soil contamination. After packing, crops are hydro-cooled either by potable equipment on the headland or at a packhouse. Pumpkins

Some crops may be washed in the field depending on soil contamination. Up to 10 t hr-1 water jets having low usage re-circulation system with water replaced each day, but may be longer.

Asparagus

The crop may be washed to remove soil particles from the base of the spears. Also, if holding is essential, and if the crop is being marketed to the multiples, then the spears must be kept cool and hydro-cooling may be used. Water for washing is usually from the mains and will be re-circulated before settlement (in a tank or lagoon) and discharge for irrigation.

3.1.3.3 Tonnage of vegetables washed and volume of water usedThe area, tonnage and an estimate of the proportion washed are shown in Table 7. The area and yield figures are from Defra HCIC data for England & Wales. The proportion of the crop washed is an estimate based on ADAS experience and information from industry contacts

There is very limited published quantifiable information on the amount of water used to wash vegetable crops. The first reaction of many growers who were consulted tends to be ‘do not know’ or ‘have not been asked this question before’. However, water usage is often metered, sometimes for individual stages in the washing process and, together with the tonnage per day or week, reliable data should be available. However, to obtain a comprehensive database a structured survey would be required. This would have to be undertaken at the appropriate time for each crop when harvesting, and hence washing, was at a peak. Some producers use borehole water, which may also be used for irrigation. This source may not be metered and may not be budgeted for in market preparation of the crop. Indeed, comment was made that, if metered mains water was used, the washing process would not be viable.

All water volumes in Table 7 are approximate as a number of factors can influence the figures: washing procedures do vary greatly with no standard system for any one crop; the quantity of water used may vary depending how readily water is available and the cost of it. For example

some producers use freely available borehole water at minimal cost whereas others have to use potable water, sometimes from the mains;

the market outlet e.g. crops for supermarkets outlets made need to be washed to a higher specification and with the requirement to use potable water for cooling and final rinse, whereas for local sales and wholesale markets there may be a lesser requirement

the amount of washing required will vary depending on amount of soil adhering to the crop. This is influenced by the soil type with little soil on crops grown on sands but more on peats and silts, also on the time of year.

Table 7 Water used in washing field vegetables, showing the area of crop (ha) tonnage (t ha-1) and (t), percentage washed and overall water use (m3) for England and Wales (values in italics for parsnip, swede and beetroot, are based on estimate rates of use similar to carrot, turnip and radish, respectively).

Crop Area t ha-1 Tonnage % Washed

Tonnage washed

Water m3 t-1

Water used m3

Carrot 7,185 74.6 536,001 95 509,200 0.1 50,920Parsnip 2,775 31.9 88,523 95 84,097 0.1 8,409Turnip 174 15.5 2,697 90 2,427 0.3 728Swede 720 34.2 24,624 95 23,393 0.2 4,679Beetroot 1,630 36.5 59,495 50 29,746 0.2 5,949Radish 140 8.9 1,246 95 1,184 0.2 239

Leeks 1,720 26.7 45,924 100 45,924 0.56 25,717Salad onions 1,990 14.6 29,054 90 26,149 3.5 91,522Celery 825 55.1 45,457 98 44,548 0.3 13,364Asparagus 700 1.9 1,330 45 599 3.6 2,156

Other minor veg 250 25 6,250 100 6,250 0.5 3,125

Total 840,601 773,517 206,808References: HCIC; Defra, 2006b; Defra, 2005b

3.1.3.4 Regional distribution of water usage for washing vegetable cropsEstimates of the regional water usage to wash vegetables in the field and packhouse are given in Table 8, which is compiled using data from Table 7 and knowledge of where washing of crops takes place. This location may not be in the same county or Government Office Region where the crop is grown.

Washing of potatoes

On farm water use in the market preparation of potato crops is restricted to crisping crops. All other market preparation such as washing for pre-pack, frozen chip production, ready meals etc is carried out as a factory process at industrial premises.

Approximate Tonnage - Estimate based on production

In 2004, crisping varieties accounted for 13.6% of the total potato area planted. Approximately 12% of the potato area was seed potatoes, reducing the crisping area to 12%. With total production in 2004 at around 6.0 million tonnes, that destined for crisping was approximately 720,000 tonnes.

Approximate Tonnage - Estimate based on consumption

In 2004, consumption of potatoes in the crisping sector was estimated at 815,000 t out of 6.1 million t consumed. However, some of this will have been imported, perhaps 7%, reducing the GB grown crisping tonnage to 758,000 tonnes. If an average of the two estimates is taken, then crisping production in 2004 was around 740,000 tonnes.

Table 8 Water used in washing field vegetables, according to regions where washing takes place, showing the tonnage washed (t) and water used (m3) for England and Wales.

Government Office Regions Tonnage washed Water used m3

North East 5,354 1,359Yorkshire & The Humber 83,227 11,256

East Midlands 165,888 28,103East of England 333,576 48,307

South East 17,707 18,495South West 20,702 7,717

West Midlands 37,913 72,821North West 107,915 18,431

London 1,235 319

Total 777,517 206,808References: Vegetable Survey by Government Office Region January 2004

The crisping sector is entirely dominated by “Walkers”, who have perhaps 75% of the market and demand all potatoes are delivered to the factory already washed. “Golden Wonder” also requires potatoes to be delivered washed, but they only account for perhaps 5% of the market. Other players, such as “KP” and “Seabrook”, wash at the factory. In other words, around 80% of crisping potatoes, say 600,000 t (592,000 t) are washed on-farm.

Potato washers and rinsing

Potato washers tend to be barrel rather than brush washers. Potatoes are put in one end, are washed in a rotating barrel, and emerge at the other end up an elevator where there are rinsed, before going straight into a lorry for delivery to the factory. Typically these washers hold 4-10 m 3 of water. The amount of water required to wash potatoes will depend on how much soil is sticking to them at the time, but typically a 9 m3 washer can be expected to wash 180 t of potatoes lifted fresh from the field in summer/autumn and 230 tonnes out of store in winter. In a 12 month selling season, 4 of those months will involve sale off-the-field (July to October) and 8 out of store. Assuming equal tonnage per month are delivered, this means of 600,000 t washed, approximately 200,000 t will be washed off-the field and 400,000 t out of store.

Water usage can then be estimated as follows: off-the-field: 200,000 t @ 180 t per 9 m3 = 10,000 m3

out of store: 400,000 t @ 230 t per 9 m3 = 15,650 m3

Total water usage = 25,650 m3.

One grower mentioned an average water use for both off-the-field and out of store potatoes being 1 m3 per 30 t of potatoes, which would equate to 20,000 m3 of water for the total crop. In other words, likely total water use is in the region of 20,000 to 26,000 m3.

In addition to that in the barrel, the rinsing of the potatoes as they come out of the washer also involves some water use. Most growers report that the amount used in the rinse process more-or-less matches that lost to the washer in terms of wet potatoes loaded onto the lorry. One respondent reported the necessity to bund the washer and collect the overspill from the rinsing process, albeit a relatively low volume compared with that in the washer itself.

Geographical distribution

British Potato Council (BPC) statistics show where potatoes are grown. Ware potato crops (excluding seed potatoes) are distributed around the regions according to the proportions:

East Anglia & Cambs. 29%East Mids & Lincs. 18%Yorks, Humber & NE 12% West Mids & NW 17%Southern England 9% Scotland 14%Wales 1%

There is effectively no significant crisping area grown in Scotland or Wales, simply because of the geographical distribution of factories (they are all in England). Other than that, it would be reasonable to redistribute the Scottish and Welsh acreage to the English regions in proportion. This could mean, in terms of tonnage and water used, the distribution given in Table 9 based on Government Office regions:

Table 9 Water used in washing potatoes for crisping, according to regions where washing takes places; showing the tonnage washed (t) and water used (m3) for England.

Government Office Regions Approx. % of crisping crop

Tonnage washed

Maximum water used m3

North East 4% 24,000 1,026Yorkshire & The Humber 10% 60,000 2,565East Midlands 22% 132,000 5,643 East of England 33% 198,000 8,464South East 3% 18,000 770South West 7% 42,000 1,795West Midlands 15% 90,000 3,848North West 6% 36,000 1,539London

Total 100% 600,000 25,650Reference: BPC Yearbook of Potato Statistics in Great Britain May 2006

In terms of times of year when water is used, in the South West, crisping potatoes are mainly sold off-the-field in the period May-July, with little if any storage. Many of the other regions sell few potatoes in the period mid-June to mid-August. Otherwise, regional differences tend to be small.

3.2 Protected and horticultural crops (nationally by crop category)3.2.1 Irrigation water use (protected glasshouse crops)Protected crops are described as those grown permanently under glass or plastic cover, occupying some 1,750 ha in England (2004). (There is no equivalent area data for Wales: 418 horticulture holdings are documented in 2004, but no breakdown of crops grown). The regional distribution by Government Office Region (GOR) is shown in Table 10.

Table 10 Area (ha) and percentage total of protected cropping in England in 2004, by region (GOR).

Region Area of glass & plastic (ha) % of England total

North East 16 1North West 221 13Yorkshire & Humber 227 13East Midland 165 9West Midland 150 9Eastern England 337 19London 16 1South East 431 25South West 189 11

England Total 1751Source: Defra June Census, 2004

Glasshouse production of both edible and ornamental crops is concentrated in the South East, (mainly West Sussex and Kent), Eastern England (Herts and Essex), Yorkshire (East Riding) and the North West (West Lancashire and Cheshire).

Table 11 Area of crop categories of protected crops from Defra survey of 2005 (Defra, 2006a).

Crop 2005 Area (ha) Millions of units#

Tomatoes 206Sweet peppers 45Cucumbers 182*Lettuce 275*Other vegetables 247*

Strawberries 105Other fruit 22

Flowers and foliage 122*Nursery stock 165

Pot plants 50Bedding plants 780Plant raising 1,703

Bulbs 1,554(Total ornamentals) 450

*several crops may be planted in one season, the area shown is a factor of number of crops x area# It is estimated that the area of protected ornamental crops in E&W is around 450ha (ADAS)

Crops grown include salad vegetables, pot plants and bedding plants, flowers and bulbs, some nursery stock and soft fruit. As the economics of growing salad crops has become less attractive, more growers have turned to bedding plant production and soft fruit. The most recent estimates of areas for each crop category are those in Table 11, taken from the Defra glasshouse crops survey of 2005 (Defra, 2006a).

All protected crops will require irrigation at all times of the year, but with peak requirement during the summer months. In general, water requirements will equate to radiation levels, thus crops on the south coast will require seasonally a greater volume of irrigation applied compared to crops in the North. Energy-intensive crops such as tomatoes and peppers are usually planted later in the north than in the south to conserve fuel. This results in a shorter season and subsequently less water consumption. Water Audits were carried out in 2004 by ADAS, funded by Defra Horticulture and Potatoes Division. A total of 50 producers were visited as in the regional distribution given in Table 12, and growers were questioned on water source, storage capacity, application efficiency, water saving initiatives and environmental responsibility.

Table 12 Regional distribution of protected crops water audit carried out by ADAS.

Region Nurseries auditedOrnamental crops Edible crops Total

North East 0 0 0North West 5 3 8Yorkshire & Humber 3 5 8East Midland 4 1 5West Midland 5 2 7Wales 0 0 0Eastern England 5 7 12London 0 0 0South East 5 3 8South West 2 0 2

England & Wales Total 29 21 50

Long-season crops of tomatoes, peppers and cucumbers are mainly grown in soil-less culture in substrates such as rockwool. The system relies on drip irrigation, but due to the nature of the growing medium and variations in nozzle output, approximately 20% of water applied to rockwool crops runs to waste. Irrigation strategy is largely based on solar radiation levels or substrate water content measurements, and is computer-controlled. Leafy salad crops are generally soil-grown and watered with overhead spraylines. Watering frequency may be judged by soil moisture measurements or by experience, and growers generally acidify water to aid nutrient uptake and prevent drip nozzle blocking, frequently testing irrigation drip nozzle outputs. Estimates of water consumption for

edible crops from the survey are given in Table 13, and these show the general trend to use more water in the south than in the north, due to more intense solar radiation levels and longer cropping season.

Growers of ornamental crops rely heavily on overhead spraylines or gantry irrigation, but some hand watering with a hose may be used. Pot plants may be grown on benches or floors fitted with ebb/flood systems to re-circulate water, and soil-grown flower crops are generally watered with low level irrigation. The timing of irrigation and amounts of water given depend largely on weather and staff experience. Some growth control of bedding plants can be achieved by watering using drier regimes (withholding water at times).

Table 13 Regional estimates of annual water consumption rate (m3 m-2 a-1) for edible protected crops in 2004. Also shown are the sources of water used.

Region Protected Edible cropsPrincipal water

source% with reservoir

storage Average water use

m3 m-2 year-1

North East N/ANorth West Mains/roof water 67 0.76Yorkshire & Humber Mains/borehole 0 0.83East Midland Mains 0 0.22West Midland Mains/roof water 50 0.96Wales N/AEastern England Mains/borehole 29 1.12London N/ASouth East Mains 33 1.17South West N/A

England average 0.96** average of all crop types - long season crops (e.g. tomatoes) may use up to 1.14 that shown

Where plants are grown in pots and spaced out, irrigation using overhead methods is very inefficient, as much of the water applied runs to waste. Forced crops of daffodils under protection are watered overhead. With forced crops of tulips there is now a significant move to growing in water culture as in Holland. This requires significant investment in equipment, but low water consumption, as water is recycled. Some growers treat water with acid to reduce bicarbonate and limescale which, may leave a deposit on foliage. If recycling water, UV treatment or slow sand filtration is used to remove pathogens or particulates. Estimates of water consumption for ornamental crops from the survey are given in Table 14, but unlike edible crops there is no appreciable trend to use more water in the south than in the north, as most ornamental crops, especially bedding plants, are relatively short-season crops.

Table 14 Regional estimates of annual water consumption rate (m3 m-2 a-1) for ornamental protected crops in 2004. Also shown are the sources of water used.

Region Protected Ornamental cropsPrincipal water


storage Average water use

m3 m-2 year-1

North East N/ANorth West Mains 0 0.66Yorkshire & Humber Mains/borehole 0 0.43East Midland Mains/roof water 50 0.86West Midland Mains/roof water 20 0.64Wales N/AEastern England Mains 20 0.65London N/ASouth East Mains 40 0.39South West Borehole 100 0.48

England average 0.55

3.2.2 Irrigation water use (other protected crops)3.2.2.1 MushroomsMushrooms are the most valuable protected edible crop in the UK, far outweighing tomatoes. In 2005, some 74,000 tonnes were produced (Basic Horticultural Statistics 2006 – Defra, 2006b). Mushroom farms are located in several parts of the country, and there are thought to be no regional variations in water use for mushroom production. Production is all year round in fully enclosed buildings and is not seasonally affected, but as profitability has declined many farms have closed in recent years.

Hose and rose and watering trees are the most common means of irrigating mushroom crops, with a trend towards trees (a semi-automated frame system fitted with irrigation nozzles which is pulled through the cropping shed) recently. A typical mushroom producer, growing in trays on home produced compost (210 tonnes of Phase I compost per week) uses around 500,000 litres per week. Per area of growing bed this equates to 30-40 l m -2.

In addition to crop irrigation, water is needed in the composting process (which often takes place away from the farm at specialist compost producers). Composters estimate to use 1000 litres of water per tonne of Phase I compost produced. The composting process is contained, so there is no run-off and no waste as all water used is recycled.

The following is a seasonal/application breakdown from a typical grower from a recent water audit carried out: Crop watering 15% Washing down 15% Compost production 25% summer, (10% winter) Boilers (steam production) 30% summer, (40% winter) Non-allocated 15%

A “scaled up” water consumption estimate to include all E&W mushrooms is: 733,500 m 3 per annum.

3.2.2.2 Outdoor Nursery StockNursery stock is predominantly containerised production, apart from some rose and tree production, which is field grown, and the regional distribution is shown in Table 15.

Table 15 Area (ha) and percentage total of outdoor nursery crops in England in 2004, by region (GOR), and the number of sites surveyed by ADAS in 2000 (see text).

Region Area of outdoor nursery stock

% of England total Number surveyed by ADAS

North East 129 2 0North West 499 7 4Yorkshire & Humber 545 7 5East Midland 752 10 4West Midland 1,196 16 6Eastern England 1,578 21 7London 55 1 1South East 2,185 29 16South West 706 9 7

England Total 7645 50Source: Defra June Census, 2004

Production is mainly concentrated in the south east of England and East Anglia, and Water Audits were carried out in 2000 by ADAS, funded by MAFF Horticulture and Potatoes Division. A total of 50 Container Nursery Stock growers were visited, and a regional breakdown of the sites visited is also given in Table 15.

Overhead irrigation is still the predominant method for nursery stock, and such systems are not efficient with up to 50% of water applied lost. Some growers were using capillary sandbeds and ebb and flood systems, while larger specimen trees were generally irrigated using drip systems, but such systems are costly. The timing of irrigation and amounts of water given depend largely on weather and staff experience, and some growers treat water with acid to reduce bicarbonate and limescale deposits on the foliage. Growers using run-off water from yards and bed areas usually used slow sand filtration to remove particles and some potential pathogens before re-use. Estimates of water consumption for outdoor nursery stock from the survey are given in Table 16.

Table 16 Regional estimates of annual water consumption rate (m3m-2a-1) for outdoor nursery crops in 2000. Also shown are the sources of water used.

Region Container Nursery StockPrincipal water


storageAverage water use

m3 m-2 year-1

North East N/ANorth West Mains/borehole 75 0.53

Yorkshire & Humber Mains 40 0.77East Midland Mains 0 0.35West Midland Mains 50 0.72

Wales N/AEastern England Mains/borehole 43 0.55

London Mains 0 0.56South East Mains 31 0.49South West Mains 0 0.73

England average 0.53

3.2.2.3 Bulbs and outdoor flowersCornwall and south Lincolnshire are the main production areas. Daffodil crops are not irrigated although there have been occasions in the past when a few growers may have irrigated prior to harvest (to 'aid harvesting', i.e. help avoid clod formation). There is very little outdoor tulip production now. Lily growers tend to use trickle irrigation in most situations from mains, especially where grown in Spanish tunnels. In outdoor beds trickle is most commonly used.

Other outdoor flower crops (asters, sunflowers, sweet-william, etc) are mainly grown in Lincolnshire, and trickle tends to be used for most of these crops where it is important to keep the foliage dry. A regional breakdown of the area of outdoor flowers and bulbs is given in Table 17 below. No detailed consumption data are available.

Table 17 Area (ha) and percentage total of outdoor flower and bulb crops in England in 2004, by region (GOR).

Region Area of bulbs & outdoor flowers (ha) % of England total

North East 14 <1North West 153 3Yorkshire & Humber 40 1East Midland 2,150 37West Midland 98 2Eastern England 699 12London 24 <1South East 141 2South West 2,435 42

England Total 5,754Source: Defra June Census, 2004

Growers of ornamental crops rely heavily on overhead spraylines or gantry irrigation, but some hand watering with a hose may be used. Pot plants may be grown on benches or floors fitted with ebb/flood systems to re-circulate water, and soil-grown flower crops are generally watered with low level irrigation. The timing of irrigation and amounts of water given depend largely on weather and staff experience. Some growth control of bedding plants can be achieved by watering using drier regimes (withholding water at times).

3.2.3 Washing of protected and horticultural crops3.2.3.1 Edible cropsMost crops are harvested without any need for washing before marketing. The only exception to this would be washing of glasshouse radish after trimming and prior to packing. Washing of baby-leaf and mixed leaves for salad packs is considered to be carried out post “farm-gate”.

3.2.3.2 Ornamental cropsSome pot plant nurseries use automated pot washing lines for cleaning plastic pots before marketing, and some of this water is recycled. Many bedding plant nurseries irrigate loaded Danish trolleys prior to despatch to maintain freshness, especially during hot weather. This may be by using hand watering or an automated irrigation “tunnel” through which the trolleys pass.

3.2.3.3 MushroomsThe crop is seldom washed prior to marketing.

3.2.3.4 Nursery stockMost nurseries use pot washing lines for cleaning plastic pots before marketing. Some of this water is recycled. Some nurseries irrigate Danish trolleys loaded with small plants prior to despatch to maintain freshness, especially during hot weather. This may be by using hand watering or an automated irrigation “tunnel” through which the trolleys pass, as for ornamental glasshouse crops.

3.2.3.5 Bulbs and outdoor flowersNarcissus bulbs are treated with hot water (and formaldehyde) to control bulb scale mite, which uses small amounts of washing water.

3.2.4 Overall water use by protected and horticultural crops Compiling all the above available sources of information estimates of water use in the protected and nursery stock components of the horticultural sector of agriculture can be arrived at, and for each sector the annual water use is given in Table 18 below. These values are for the whole of the UK, and can be broken down into the regional components for the protected crops, nursery stock, and bulbs & outdoor flowers categories for England, which are given in Tables 19, 20 and 21 respectively.

Table 18 Estimated annual water use in horticulture by sector (UK) (figures in italics are estimates based on advisor knowledge as most flowers and bulbs are grown without irrigation).

Sector Cropped Area (ha) Water use (m3 ha–1 a-1) Water use (M m3 a-1)

Protected edibles 1,082 9,600 10.39Mushrooms N/A N/A 0.74Protected ornamentals 450 5,500 2.48Nursery stock 9,519 5,300 50.45Flowers & bulbs 5,726 250 1.44

Table 19 Estimated annual water use by protected crops by English region.

Region Area of glass & plastic (ha) Water use (M m3 a-1) *

North East 16 0.12North West 221 1.68Yorkshire & Humber 227 1.73East Midland 165 1.25West Midland 150 1.14Eastern England 337 2.56London 16 0.12South East 431 3.28South West 189 1.44

England Total 1751 13.31*using average water consumption for all protected crops of 7600 m3 ha-1 year-1

Table 20 Estimated annual water use by nursery stock by English region.

Region Area of nursery stock (ha) Water use (M m3 a-1) *

North East 129 0.68North West 499 2.64Yorkshire & Humber 545 2.89East Midland 752 3.99West Midland 1,196 6.34Eastern England 1,578 8.36London 55 0.29South East 2,185 11.58South West 706 3.74

England Total 7,645 40.52*using average water consumption of 5,300 m3 ha-1 year-1. Actual consumption may be lower, as areas include field-grown stock as well as container stock.

Table 21 Estimated annual water use by bulbs and outdoor flowers by English region.

Region Area of nursery stock (ha) Water use (‘000 m3 a-1) *

North East 14 3.50North West 153 38.25Yorkshire & Humber 40 10.00East Midland 2,150 537.50West Midland 98 24.50Eastern England 699 174.75London 24 6.00South East 141 35.25South West 2,435 608.75

England Total 5,,754 1438.50*using average water consumption of 1.44 m3 ha-1 year-1. Actual consumption may be lower, as areas include field-grown stock as well as container stock.

3.3 Livestock FarmingData are available from recent studies and surveys. In some cases, estimates have been derived as part of recent reviews of excretal output of livestock or towards the development of a manures inventory within the PLANET Nutrient Management Decision Support Software. Guidelines are available as part of “Best Practice”, published by the Environment Agency (2003) and what are presented as “typical stock requirements” are summarised in Table 22.

Table 22 Typical stock water requirements (source: Environment Agency, 2003).

Animal System Water volume (L day-1 per animal)Dairy cattle Cleaning, non-power hose 14-22

Cleaning, power hose 27-45Drinking1 45-70

Calves Drinking 15-25Beef cows Drinking 25-45Pigs2 Cleaning after each batch (10

pigs/pen)16-24

Lactating sows 15-30Pregnant sows and boars 9-14Weaners 5

Sheep Drinking 2.5-5.0Dipping (per dip) 2.5

Poultry Layers (per 100 birds) 20-30Fattening (per 100 birds) 13Turkeys (per 100 birds) 55-75

1 Higher values for lowland production in S. England2 For outdoor pigs the maximum estimated requirement should be increased by 50% to allow for wastage and wallows

It is worth noting that within an associated study on water use (Environment Agency, 2003), a total of 33 dairy farms were sent water use questionnaire forms - with not a single response!

3.3.1 Dairy and beef cattleA survey of 31 commercial dairy farms undertaken in England, Scotland and Wales in 2004 provided information on the composition, management and production of dairy cattle slurry, farmyard manure (FYM) and dirty water, storage facilities and land application timing (Laws & Chadwick, 2006). On average, each cow generated 13.6 m3

undiluted slurry and 6.2 m3 of dirty water over the winter housing period. Slurry comprised 67% excreta on farms handling dirty water separately, and 61% excreta on farms with total containment. Parlour washings accounted for 19% of total slurry and 50% of total water addition to slurry on farms with total containment.

The amount of water used for washing the parlour and associated yards was based on measured hose flow rates and daily usage. Average daily water use was 28 L cow-1 (range 17 – 40 L cow-1) when high-volume hoses (average flow rate 97 L min-1) were used in the milking parlour, 22% more than for low volume hoses, at 23 L cow-

1 (range 13 – 30 L cow-1). Previous guidance on dairy, milk tank and pipeline cleaning and collecting yard wash-down was given in the Water Code (Anon, 1998): 35 litres cow-1 per day for power hoses; 18 cow-1 per day for non-power hoses.

On the basis of the above estimates, daily usage of 30 L cow-1 and 20 L cow-1 have been assumed as reasonable guidelines for high and low volume hoses, respectively, within the recent PLANET manure inventory. The caveat, that volumes can range widely between farms, is important and it is recommended that actual water volumes used should be measured (as outlined by Laws & Chadwick, 2006), as large volumes of water are involved. For the purposes of this review, an average of the above estimated daily rates, at 25 L cow-1, has been used in the estimation of regional wash water requirements.

The use of wash water for cleaning purposes is normally confined to the dairy production, the milking parlour, the bulk milk tank, pipelines and the collecting and dispersal yards. Unless there are specific animal disease or health reasons, no cleaning water is used in stock accommodation for both adults and young stock, whether dairy or beef. Periodically, slurry or manure and soiled bedding are cleaned out and fresh litter spread, perhaps after a disinfectant spray. Depending on the condition of the animals, there may be an additional requirement for stock washing in the case of finished beef cattle, for compliance with meat hygiene requirements (Anon, 2002).

Typical drinking water volumes are shown in Table 22 and estimates provided by specialist consultant experience are shown in Table 23. The values given here are close to the range cited in Table 22. Of course, in dairy cows, it is well known that drinking water demand is closely associated with the level of milk production and, in general with grazing animals, water consumption and urinary output are impacted by the DM content of herbage and weather conditions (Smith & Frost, 2000). It is clear that the demand for water, for stock drinking purposes is much greater than that for cleaning and washing down.

Table 23. Drinking water requirements for cattle (source: Cottrill, 2006)1.

Animal Water volume (L day-1 per animal)

Total volume (L animal-1 per year)

Dairy cow - lactating 104.52 32,4212

Dairy cow – dry period 20 10953

Dairy cow – overall 91.8 33,516Beef cow 20 7,,300Dairy and beef bull 20 7300Calves 5 1,8254

1 Bruce Cottrill, ADAS, personal communication2 Approx 5 litres water intake per kg milk yield. Ave milk yield per cow in the UK, 2003 – 7000 kg year-1 over 335 day lactation, c. 85% overall (source: MDC, 2004) Dairy Facts and Figures)3 Assuming a dry period of approx 2 months, or c. 15% overall4 Calves normally up to 6 months, but census data may be representative of year-round numbers.

3.3.2 Sheep productionSome typical drinking water requirements for sheep are available though specialist experience (Kate Phillips, ADAS, personal communication):

Non-pregnant lowland ewes - 3.3 L day-1

Ewes in early pregnancy - 4.2 L day-1

Ewes in mid pregnancy - 5.2 L day-1

Ewes in late pregnancy – 7.0 L day-1

Ewes in early lactation - 7.3 L day-1

These requirements vary enormously according to diet, body weight and the number of lambs reared. On very wet diets like stubble turnips, water intake will be low but on straw-based diets indoors, intakes will be high. Pregnancy lasts 145 days, (early pregnancy would be about 40 days; mid pregnancy 60 days and late pregnancy 45 days). Lactation is from 6 to 20 weeks, with an average of about 14 weeks, although milk yields and, hence, water consumption peaks at about 3 weeks after lambing and declines thereafter. Based on these figures, the overall average water consumption per ewe, for drinking purposes, is estimated at 4.5 L day-1. For lambs, drinking water requirements are around 2 L day-1 after weaning (at c. 100 days) - then rising steadily as they mature, up to a level similar to that of adult ewes. A high proportion of lambs (say 60%) is finished in early October, with a calculated overall daily water requirement estimated at 1.4 L lamb-1 day-1. With the remainder (c. 40%) kept on as store lambs until late February, drinking an estimated 3.3 L day-1 (assumed similar to non-pregnant ewes), the overall average water consumption is calculated as 1.7 L day-1 over a full year.

As with adult and young cattle, there is no requirement for cleaning wash water during or following the housing period, which is usually of short duration only. Ewes may be housed before and after lambing, for perhaps up to 80 days, this depending on the time of lambing, climate, topography and soils.

Dipping and foot bathing, however, make a significant demand for water. Foot baths are of various sizes; walk-through ones may hold 100 litres but stand-in ones may hold 300 litres. Foot bathing is done very regularly on

some farms; weekly through the housing period if footrot is a problem, otherwise perhaps 4 times a year in many flocks. For dipping, baths hold say 500 litres, or more, and sheep are dipped once or twice a year, although the number of flocks dipping has fallen dramatically due to concerns over pollution. Bryson (1984) estimates water requirements for dipping within a range from 1 litre per head up to c. 4 litres per head, depending on the type of bath. The same author makes a general estimate of 2.25 litres per head.

3.3.3 Pig ProductionWashing of pens between batches of growing/finishing pigs is an important and substantial requirement. However, guidance on wash water requirements has been minimal in the past, with the Water Code suggesting a volume of 18 litres per batch of pigs (10 pigs per batch) (Anon, 1998). This seems an unrealistically low value bearing in mind that the volume would amount to a single, large bucketful of water with which to clean a sizeable pen, including residual slurry and dung solids. A rather higher estimate is given in the Environment Agency guidance in Table 22 above, at 16-24 litres per animal for cleaning after each batch, i.e., a total volume of 160–240 litres per batch, which appears more realistic.

In the absence of other data on wash water volumes, an approach was made based on pig producer and consultancy experience on pen cleaning procedures, measured hose flow rates and observed/estimated hosing duration on commercial units (Mike Brade, ADAS, personal communication). Estimates of water use on a “per batch” basis, in the absence of more detailed information about the size of the unit and the period and number of production cycles during the year, do not allow the demand for water to be assessed in the context of a production unit. Therefore, in order to allow a rational approach, which would facilitate meaningful estimates covering the range of stock types and enable extrapolation to a practical pig unit, calculations are based on a notional production unit with 400 sows. An outline of the notional ‘typical’ unit is presented, as follows, and the calculation of wash water volume requirements, laid out in Tables 25 and 26. The latter approaches acknowledge that production is often organised around specialist units, where pigs of a certain type may be reared, rather than the whole cycle from farrowing to finishing. 400 sows @ 21 pigs per sow per year = 8400 pigs production;these represent 8400/52 = 161.5 pigs per week (say 162);400 sows, each producing 2.3 litters per year = 920 litters per year are produced.

Calculation of accommodation requirement on the unit:No. of pig places

With each farrowing period (5 weeks), no. of places required is 920 x 5/52 = 88.5 (say 90)Weaners (7 - 18kg LW) for 4 weeks, i.e. 162 per week for 4 weeks = 648 (say 650)Growers (18-35kg LW) over 5 weeks, i.e. 162 per week for 5 weeks = 810Finishing (35 -105kg LW) over 11 weeks, i.e. 162 per week over 11 weeks = 1782

It can be seen that the estimates of wash water volume at 1.6-2.6 L pig-1 week-1, for weaners, growers and finishers, are still rather higher than the guideline requirements of 16-24 litres per batch of 10 pigs per pen, in Table 22 (Environment Agency). The comparison needs to take account of the time that each batch would be held; i.e. 4-11 weeks, depending on stock type. Moreover, the published guidelines make no distinction between sows and progeny, where it is clear that there are substantial differences in the use of wash water.

Table 24. Estimates of drinking water requirements for pigs (litres pig-1 day-1).

Category Consultancy estimates1

Research estimates2

Dry sows & gilts 6.0 10.0Farrowing sows 30.0 21.0

Weaners 2.0 1.6Growers 4.0 3.4Finishers 5.5 5.7

1 Source: Mike Brade, ADAS 2 Derived from relationships between meal and water intake and slurry output (Smith et al., 2000)

Estimates of drinking water requirements are included in Table 24. Estimates based on expert opinion (according to specialist pig consultancy experience - Mike Brade, ADAS, personal communication) agree reasonably well with those derived from published research data (Smith et al., 2000). The latter were established from observations that growing pigs with ad libitum access to water consumed 2.76 litres of water per 1 kg meal intake.

Few data are available that can be used for validation purposes. However, growers often have a good estimate of total water usage on their own units and it is possible to compare the estimated total water usage (drinking

water + wash water requirements) on our notional 400 sow unit, with such commercial estimates. In this way, the total drinking water requirements are estimated at 16.46 m3 per sow and the wash water at 1.56 m3 per sow (including all progeny). This results in a total of 18.0 m3 per sow and 1.97 m3 per sow, after allowing 10% extra volume due to drinking water leakage (a factor often used in estimation of slurry volume calculation on commercial units). Thus drinking water requirements represent over 90% of the total water requirements of pig production. At a cost of £0.89 per m3 water supplied, this suggests an annual cost of £16.00-17.50 per sow, which compares closely with £17-20 per sow for water costs on commercial units, thus indicating that the estimates are fairly representative of commercial production.

Table 25. Estimation of wash water volume requirements for different categories of stock on 400 sow unit with progeny retained up to bacon weight.

A B C D E F G H3 I4 J5

Category Weeks per

cycle

No. of places

No. of

pens

Clean time

(mins)

Batches per year

Occupancy %

Total wash time

(mins)

Annual water vol (L)

Wash water use

L/batch

Water use L/pig/wk

Dry sows & gilts

52 310 100 7201 9,821 0.62

Farrowing sows

5 90 90 15 10 96 13,500 184,113 204.6 39.42

Weaners 4 650 43 10 11.5 90 4,983 67,963 136.4 2.0Growers 5 810 54 15 10 96 8,100 110,468 204.6 2.6Cutters 8 1,296 86 18 6 95 9,331 127,259 245.5 1.9

Finishers 11 1,782 119 20 4.5 95 10,692 145,818 272.8 1.6

Notes & bases for calculations:1 wash water for dry sows & gilts on straw yards – 2.323 m2 head-1 stocking density and approx. 1 minute m-2 yard area for hose use after removal of FYM, 1x/year 2 summary wash-water volumes can be presented on a per sow/week basis as for other categories; but dry periods and lactation should be integrated to single estimate = 9.6 L sow-1 per week3 column H = G x 3 gallons/minute (hose delivery) x 4.546 litres per gallon4 column I = column H / (column C x column E) 5 column J = column H / (column B x 52 weeks)

Table 26. Estimation of wash water volume requirements for pig production with production

organised in different ways, from breeding sows only (herd type 1) to breeding stock and all progeny to bacon weight (herd type 4); also specialist weaners, growers and finishers, only (types 5 – 7).

Annual water Wash water volume estimates for herd types (HT)Category vol (L) 1 2 3 4 5 6 7

Dry sows & gilts 9,821Farrowing sows 184,113 193,934

Weaners 67,963 261,897 67,963Growers 110,468 372,365 110,468Finishers 145,818 518,182 145,818

Litres sow-1 per yeara 485 655 931 1296 - - -Litres pig-1 per weekb 9.3 12.6 17.9 24.9 2.0 2.6 1.6

Notes - definition of herd types:

1. Breeding to (sale @ approx 7kg) weaning (Dry sow and farrowing only)

2. Breeding to sale @ approx 18kg (weaners) (Dry sow and farrowing + 1st stage)

3. Breeding to sale @ approx 30kg (Dry sow and farrowing + 1st & 2nd stages)

4. Breeding to slaughter (sale @ bacon wt) (Dry sow and farrowing + 1st & 2nd stages + finishing)

5. Farrowing to sale @ approx 18kg (weaners) (1st stage only)

6. Sale @ approx 30kg (2nd stages growers)

7. Sale @ bacon wt (finishing 35kg - 105kg)a Calculated from the total volume in column above divided by number of sows; e.g. Type 1 = 193934/400 sowsb Calculated as above, divided by number of weeks for each category - Type 1-4, 52 weeks; Type 5 – 4 weeks; Type 6 – 5 weeks; Type 7 – 11 weeks.

Table 27. Typical water consumption for poultry species.

Species Cycle length(including clean out)

Drinking water(L bird-1)

Stocking density (birds m-2 floor

area)

Notes

Replacement pullets (for commercial egg production)

19 weeks 10.2 (cumulative from day old to transfer at 16 weeks)

12 Stocking density is based on compliance with Defra Welfare Codes (17kg/m2 for birds reared on litter)

Laying hens – cage egg production

58 weeks 80 (cumulative from 16 weeks to 72 weeks of age)

22 Stocking density is based on four-tier cages

Laying hens – non-cage egg production

58 weeks 87 (cumulative from 16 weeks to 72 weeks of age)

11.5 Stocking density quoted is typical of free range and barn systems, but not organic production

Broilers 56 days 10 (cumulative from day old to 49 days of age)

12 Assumes that flocks are not ‘thinned’ – all birds grown to 49 days

Broiler breeders 46 weeks 60 (cumulative from 20 to 64 weeks of age)

6 Stocking density is based on compliance with Defra Welfare Codes (25kg/m2)

Ducks 63 days 60 (cumulative from day old to 49 days of age)

7 Note that due to duck behaviour and choice of drinker, water use varies considerably between sites

Turkeys (male) 22 weeks 100 (cumulative from day old to 20 weeks of age)

2.2 Commercial practices very variable - data are based on male turkeys (stags) reaching a liveweight of 17kg at 20 weeks of age

Turkeys (female) 18 weeks 50 (cumulative from day old to 16 weeks of age)

4.3 Commercial practices very variable - data are based on female turkeys (hens) reaching a liveweight of 9kg at 16 weeks of age

3.3.4 Poultry It has been possible to derive estimates of washing water requirements from some of the companies that supply the cleaning chemicals (disinfectants etc.) for poultry houses, since these companies produce recommendations for the quantities of water to use and dilution rates for their particular products. Because of product differences, of course, there are differences in rates of water use. Other important issues include: diligence of the producer some producers will try to remove as much of the visual contamination as possible by dry cleaning, so that

they use less water in total high versus low pressure washing systems building differences e.g. surface absorption, run-off etc.

Accepting these variations, the easiest way to express water use is on the basis of “litres of water per square metre of floor area” and “per cycle”. Because walls and roofs need to be cleaned as well as floors, the norm is to

multiply the floor area (m2) by a factor of 2.5, to arrive at a total area to be cleaned (i.e. floor + walls + roof). This does not include any outside concrete apron areas that would also need water for cleaning - these vary greatly in area, but can be large in order to allow easy access for vehicles.

The amount of water needed, on this basis, should be the same for broiler houses, turkey houses, duck houses and pullet rearing (for egg production), on litter systems, since the buildings are all essentially the same when it comes to cleaning out. One chemical company recommends using 2000 ml (2 litres) of water m-2 of floor area. Another gives a range, but up to a maximum of 1850 ml m-2 of floor area. It seems reasonable to assume an overall figure of 2 litres m-2 as a round figure. For free range laying houses, the same estimate might be used, but normally the raised slatted floor area is dismantled and cleaned separately. This might cover about two thirds of the floor area, so a factor of “floor area x 3” is proposed (rather than floor area x 2.5, as above). It is anticipated that water use for cage egg production systems and cage rearing of pullets would also be similar to this, and higher than broilers because of increased number of tiers and because the cages themselves have to be cleaned properly. A consultancy “best guess”, therefore, for wash water requirement of caged production systems, would be similar to that assumed for the free range laying systems. The above estimates have been provided by Jason Gittins, ADAS (personal communication).

As with other species, the drinking water requirements of poultry are much greater than for washing water. Data on typical drinking water consumption and length of the production cycle of the major poultry types, are summarised in Table 27 and are based on information collected from a number of commercial producers (Jason Gittins, ADAS - personal communication).

Typical or regulated (according to Defra Welfare Codes) stocking densities are also provided in Table 27, these data being necessary in order to relate overall bird numbers from the census data, to wash water volume requirements, estimated as above on the basis of floor area of the housing.

3.3.5 Overall discussion of livestockThe coefficients for drinking water and wash water requirements have been summarised within Table 27. Animal categories identified within the Defra census don’t always fit neatly within the groups readily recognised within commercial production and for which data on water requirements have been derived as outlined in the sections above. Thus beef store cattle and growers as dairy replacements are considered together. Similarly maiden gilts and “barren sows fattened for slaughter” are growing pigs and considered together with finishing pigs in terms of drinking water, and with dry sows for wash water since they are likely to be relatively few in number and kept on straw rather than a slurry system.

Annual requirements per animal, for both drinking and wash water, are presented in Table 28. These data have then been combined with the census numbers for livestock and estimates made for total requirements, both on a regional and national basis (Table 29 and Figure 7). It can be seen, in each case, that wash water requirements are of relatively minor importance. The cattle sector is the major consumer, with a total requirement of c. 82 million m3, followed by sheep, at 17 million m3, poultry at 12 million m3 and pigs at c. 8 million m3 – a total of 156 million m3, overall. No attempt has been made to profile these requirements throughout the year. It is likely that a fairly flat profile would be observed for the pig and poultry sector, with production dominated by mostly year-round housing systems. For sheep and cattle, peak demands are likely during the summer months, but as outlined earlier drinking water intakes of animals at grass is much affected by the dry matter content of herbage as well as weather conditions and, in the case of dairy cows, milk yields.

3.3.6 Equestrian industry usageThe equestrian industry is not generally regarded as part of the agricultural industry, but rather that of “leisure”. However, the layman may consider the keeping of horses as an agricultural pursuit and it is instructive to compare the estimates of horse numbers and water use alongside those other livestock. There are currently an estimated 1.35 million horses in Britain of all categories and sizes (BETA, 2006). An average live-weight of 500 kg is often used for horses, and their daily drinking requirement is something like 4-5% of live-weight sizes (G. Fairfoull, ADAS equine consultant, pers. comm.). Therefore for drinking alone an estimated 12.4 M m3 of water is required annually, and to this will be added that which is used for washing down both horses and yards. The majority of this usage will be located in England, but this value also includes horses in Scotland and Wales. A regional distribution of horses by each category is available in the National Equestrian Survey, last published in 1999, in which the overall number was quoted as 0.9 million animals, but currently being updated (BETA, 1999).

Table 28. Summary of data used to estimate drinking and wash water requirements for livestock production.

Category Production cycle

(weeks)

Occupancy1

%L animal-1 per day Other

requirementsL animal-1 yr

Drinking Wash Drinking WashCattleDairy cow 56 - 91.8 25 33,516 9125Growers & replacements 52 - 20.0 0 7,300 0Beef cows & heifers 52 - 20.0 0 7,300 0Dairy & Beef bulls 52 - 20.0 0 7,300 0Beef store cattle 52 - 20.0 0 7,300 0Dairy & Beef calves 9 - 5.0 0 1,825 0PigsDry sows & gilts 52 78 6.0 0.086 1,708.2 24.5Boars 52 100 6.0 0.086 2,190.0 31.4Farrowing sows 5 22 30.0 5.63 2,409.0 452.1Maiden gilts 10 100 5.52 0.0863 2,007.5 31.4Barren sows 10 100 5.52 0.0863 2,007.5 31.4Weaners (<20 kg) 4 100 2.0 0.286 730.0 104.4Growers (<50 kg) 5 100 4.0 0.371 1,460.0 135.4Finishing pigs 11 100 5.5 0.229 2,007.5 83.6Sheep Dipping

L/event/headDipping L/animal/year

Total ewes 52 - 4.50 0 2.25 1,644.3 4.5Rams & other adult sheep 52 - 3.30 0 2.25 1,204.5 4.5Lambs under 1 yr 52 - 1.68 0 2.25 613.5 0.9Poultry batch -

L/m2 floor area

St density - birds/m2

Pullets 16 84 0.0911 5.0 12.0 33.24 1.1404Broilers 7 88 0.2041 5.0 12.0 74.49 2.7083Laying hens - caged 56 97 0.2041 6.0 22.0 74.49 0.2445Laying hens - non-caged 56 97 0.2219 6.0 11.5 81.01 0.4678Broiler & layer breeders & cocks

44 96 0.1948 5.0 6.0 71.10 0.9420

Ducks 7 78 1.2245 5.0 7.0 446.94 4.1270Turkeys (m) 20 91 0.7143 5.0 2.2 260.71 5.3719Turkeys (f) 16 89 0.4464 5.0 4.3 162.95 3.3592

Notes: 1 – census data assumed to represent animal numbers throughout year; occupancy figures used only in pigs where sow farrowing time taken into account

2 – maiden gilts & barren sows for fattening assumed to have similar drinking requirements to growing pigs as both categories are growing3 – maiden gilts & barren sows for fattening assumed to have similar wash water requirements to dry sows kept on straw

Table 29. Estimated total water requirements for livestock production in England – figures in millions of cubic metres (M m3) for 2004.

Livestock Total Regioncategory England E Mids East London N East N West S East S West W Mids Yorks &

HumberCattle 81.999 6.826 2.378 0.052 2.425 16.402 6.505 28.246 11.909 7.255Pigs 7.875 0.796 2.261 0.004 0.143 0.309 0.567 0.884 0.444 2.466Sheep 17.272 1.383 0.384 0.003 2.103 3.260 1.540 3.680 2.556 2.363Poultry 11.956 2.118 3.016 0.026 0.184 0.822 1.068 1.670 1.658 1.394Total 119.102 11.123 8.039 0.086 4.855 20.794 9.680 34.480 16.566 13.479

Figure 7 Summary of regional estimates of water requirements for livestock production (M m3).

3.4 Sources of water for on-farm useWater used on farm can come from either one of two broad categories of supply, either directly abstracted water used solely for the farm application , or from the public mains supply which is ultimately abstracted from the same natural sources but treated to provide a standard quality. The 1980 Strutt report (Strutt, 1980) said very little about the source of water used on farms, save that about 5% of that supplied through the public mains was supplied to agricultural and horticultural holdings. Between 1971 and 1977 direct abstraction for agricultural purposes amounted to 87 – 112 M m3 a-1 compared with 5236 – 5368 M m3 a-1 for the public supply, and by 2003 this had risen to about 163 M m3 (447 ML per day) for agricultural use compared with 6176 M m3 (16920 ML per day) for the public supply (Defra , 2005a). We are therefore using about 20% more water as a nation (England and Wales) than thirty years ago, whilst agriculture is using 50 – 100% more.

3.4.1 Irrigation usage3.4.1.1 Outdoor cropsThe irrigation surveys from 1982 onwards also included records of the source of water used and these are given in Table 30 below (Weatherhead & Danert, 2001), where further subdivision is provide for surface and ground-water sources in years 1984, 1990 and 1995 (Stansfield, pers. comm.), and for some other sources in 2001 (Weatherhead & Danert, 2001). As these indicate the major part of the water used in irrigation comes from separate abstraction, either from surface waters (rivers, streams, ponds etc) or groundwater (boreholes and springs) and only about 4% from the public mains supply.

Table 30 Volume of water used for irrigated outdoor crops (‘000 m3) in England and Wales (1995 & 2001 England only) taken from different sources.

Source of water

Year

1982 1984 1987 1990 1992 1995 2001Surface water 34,390 57,210 19,250 74,070 41,820 90,860 75,760(watercourse) (47,480) (62,330) (76,760)(lake or pond) (9,730) (11,740) (14,660)

Groundwater 16,680 32,420 11,800 50,540 28,470 61,620 47,810(spring or well) (7,580) (8,590) (8,620)(deep borehole) (24,840) (41,950) (53,710)

Public supply 2,040 3,840 1,100 3,860 2,620 4,390 4,300

Other source 1,830 3,540 1,470 5,330 2,160 4,880 3,430(collected rain) (2,050)(re-used water) (670)

Total 54,940 97,730 33,630 133,790 75,070 164,070 131,300

To be able to abstract water a licence is required from the Environment Agency, which defines a maximum amount that is allowed to be abstracted. Up to 2003, a licence was only required for irrigation needs applied as a spray according to the 1991 Water Resources Act and previous legislation. As such the total annual amount licensed rose from about 55 M m3 in 1974 to about 145 M m3 in 1997 according to the analysis of future irrigation needs by Weatherhead and Knox (2000). Actual use was about 20-40% of this amount and the actual proportions for the period 1990 to 2003 are shown in Table 31 where the actual daily abstraction from both surface and ground water-sources are shown as ML per day as given in Government statistics (Defra, 2005a; from EA sources), and Figure 8.

Table 31 The actual rate of daily usage of abstracted water from both surface and ground-water sources (ML day-1) and that amount licensed for abstraction (ML day-1) (Defra , 2005a).

Year1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003

Spray irrigationActual 377 366 269 164 283 352 369 292 282 325 291 259 248 315Licensed . . 748 806 769 781 808 846 904 954 937 947 949 936 933

Other agricultural useActual 128 131 129 139 115 103 136 108 111 142 152 108 120 132Licensed . . 243 264 374 343 306 371 329 378 421 417 385 370 352

Figure 8 shows the proportion (%) of licensed abstraction that was actually used for both spray irrigation and other agricultural uses, and although both vary year upon year, that for irrigation varies much more according to irrigation needs and actual rainfall, than that for other agricultural uses which varies around 36%. The proportion of the total volume abstracted that accounts for spray irrigation though has remained reasonably constant at about 20-25% since 1995 (Figure 9).

The variation of irrigation usage between years according to weather patterns also hides the fact that this usage is confined to only 3-4 months of the year, and it is the variation in weather patterns between the months of May and August (chiefly June and July) which really govern the amount of water actually used for irrigation. Other agricultural uses are more evenly distributed throughout the year. This has enormous implications for the amount of abstraction that can be licensed and the source of abstraction, as this is precisely the period when volume of both ground water and surface water are at their lowest availability within catchments.

Table 30 above shows that the 2001survey contained a further sub-division of the “other” source of water supply, namely collected rainwater and re-used water. These are useful recent innovative sources of water to augment the summer abstraction regime, but of course require an on-farm reservoir to contain them. A more common reason to employ a reservoir on-farm is to spread the abstraction load on local water supplies so that water can be abstracted during peak flow winter periods and stored for later summer use. This is increasingly common and favoured by EA when granting abstraction licences, especially since the governmental review of the licensing system in 1999. Subsequent to this review the Government has also introduced the Catchment Abstraction Management Systems (CAMS) with the aim of making information on abstraction more open to the public. In addition, the CAMS process will provide a more consistent and structured approach to local water management, provide a framework for operating time-limited abstraction licences and facilitate licence trading between users within the catchment.

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Figure 8 Proportion of licensed daily usage estimated to be actually used for spray irrigation of outdoor crops and for other agricultural uses (Defra, 2005a).

The regional distribution of the amounts used for spray irrigation from both surface and ground-water sources are shown in Tables 32 & 33 respectively, and show the strong regional bias towards abstraction for irrigation in eastern regions. However, these data also show that regional variation is more or less constant over the period 1995-2003, and abstracted equally from both sources.

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Figure 9 Volumes of water (M m3) estimated to be abstracted for spray irrigation of outdoor crops and for other agricultural uses, in England and Wales (Defra, 2005a).

Table 32 The averaged actual rate of daily usage of abstracted water from surface water sources (ML day-1) for each EA region for each year between 1995 and 2003 (Defra , 2005a).

Water source

Region Year

1995 1996 1997 1998 1999 2000 2001 2002 2003Surface North West 4 5 1 1 2 1 11 22 18

North East 12 15 4 4 25 6 7 4 5Midlands 56 47 29 30 35 31 31 28 37Anglian 85 103 93 91 85 129 91 67 87Thames 6 6 5 4 4 5 3 3 4Southern 17 13 13 9 10 8 10 9 13South West 7 5 3 2 2 2 2 2 5Wales 9 9 3 3 4 3 5 7 4Total 196 203 151 144 167 186 161 142 173

Table 33 The averaged actual rate of daily usage of abstracted water from ground-water sources (ML day-1) for each EA region for each year between 1995 and 2003 (Defra, 2005a).

Water source

Region Year

1995 1996 1997 1998 1999 2000 2001 2002 2003Ground North West 2 2 1 0 1 3 2 1 8water North East 25 40 12 20 32 12 13 10 16

Midlands 40 34 19 20 25 20 23 34 26Anglian 63 68 86 61 84 58 46 48 72Thames 9 8 13 21 7 6 6 7 10Southern 10 10 6 11 6 4 5 4 5South West 4 3 2 2 2 2 2 2 3Wales 2 2 1 1 1 1 1 1 2Total 155 165 141 137 158 105 97 106 142

These are illustrated by Figures 10 and 11 which show both the regional amounts abstracted for spray irrigation in 2003 (Figure 10), and the amounts abstracted nationally from both sources between 1995 and 2003 (Figure 11). Figure 10 shows that Anglian and Midlands regions account for the vast majority of abstracted irrigation water and that in all but Thames and North East regions more water is abstracted from surface sources than groundwater (a more or less constant pattern). Nationally slightly more surface water is abstracted than groundwater (Figure 11), though both show a slight decline over this period and are fairly constant. Groundwater abstraction was lowest in 2001, which has already been identified as a “wet” year, but that abstraction of surface water for irrigation remained at similar levels to other years.

Figure 9 shows that spray irrigation actually isn’t the major use of abstracted water for agricultural purposes, and that other uses account for about three times as much water use. In these other uses however, will be a small proportion that is used for trickle irrigation. This has not been recorded separately, or as an irrigation usage, in EA returns (Defra, 2005a), although the area of trickle irrigation has been recorded by the MAFF/Cranfield University irrigation surveys. From 1974 to 1992 the area of trickle irrigation did not account for more than 2% (usually around 1%) of the area irrigated, but rose to 2.6% in 1995 and 4.8% in 2001 (Knox & Weatherhead, 2005). In fact the reference in which these proportions are quoted, also quotes he results of a survey of the trickle irrigation equipment industry carried out in 2003, which suggests that the current actual area of crops trickle irrigated is 14,899 ha rather than the 7040 ha that gave rise to the 4.8% mentioned previously. This is a difference between the surveys rather than an increase over the two years, but does suggest that currently the proportion of irrigated land that employs trickle technology may be as high as 10% (Knox & Weatherhead, 2005).

0102030405060708090

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Figure 10 Averaged daily use rate (Ml day-1) estimated to be actually used for spray irrigation of outdoor crops in EA regions during 2003, according to the source of abstracted water (Defra, 2005a).

The rise in popularity of trickle irrigation systems has been driven by three main issues, namely:1. pressure from the market for higher quality produce,2. the hitherto ability to abstract water for trickle irrigation without a licence from EA, and 3. the decline in costs of trickle irrigation equipment.

It has not really been caused by the widespread misconception that it is a more efficient use of water than spray systems. The benign abstracting regime for trickle irrigation has now come to an end however, with the implementation of the 2003 Water Act (EA, 2006) under which trickle irrigators now have to obtain a licence for abstraction (unless it is for less than 20 m3 per day). Nevertheless Knox and Weatherhead envisage the increased popularity of trickle irrigation to continue, if only because of the increasing demands for premium quality produce in the high value vegetables and soft fruits sectors.

Trickle irrigation is concentrated in these sectors and geographically this locates trickle irrigation in the regions where demand for water is already at maximum abstraction rates, namely the south and eastern areas. Table 34 below, is taken from Knox and Weatherhead (2005), and shows that more than half of water abstracted for trickle irrigation is in the EA southern region, whereas this only accounts for about 10% of overall irrigation abstraction.

Table 34 Water regulatory authority estimates of the volume of water abstracted (‘000m3) for trickle irrigation, and for all irrigation, according to EA regions (from Knox & Weatherhead, 2005).

EA Region Volume abstracted for trickle irrigation

Volume abstracted for all crop irrigation

Anglian 780 68,822Midlands unknown 25,478North East 20 8,893North West unknown 914South West 185 1,698Southern 2,550 12,024Thames 440 12,565EA Wales 220 1,362Total 4,195 131,756

3.4.2 Washing of vegetable crops and potatoes A reliable supply of water is important for the movement and washing of vegetable crops. For some crops water may also be necessary for hydro-cooling. In addition it is a requirement of Crop Assurance Protocols, to which all producers supplying supermarkets, food service sector, etc must adhere, that a risk assessment for the source of water should be carried out. Water used for final product washing must be to national drinking water standards and that recycled water must be filtered.

Water is therefore mainly drawn from the public mains or from any other source (mainly boreholes), providing its quality is of a high enough standard. Examination of potential water supplies can be carried out by microbiologists who will advise on its suitability and on any required treatment such as chlorination. Routine checking of non-mains supplies should be carried out. The customer will influence the decision on source of water, for example potatoes for crisping must be washed in potable water and therefore mains water is invariably used.

A final rinse with potable water is an essential requirement for many crops, and hydro-coolers require potable quality water at least every couple of days (some can maintain quality over short periods by chlorination) so there is usually some usage of public mains water in the entire process.

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Figure 11 Averaged daily use rate (ML day-1) estimated to be actually used for spray irrigation of outdoor crops nationally over the period 1995 - 2003, according to the source of abstracted water (Defra, 2005a).

3.4.3 Protected and horticultural crops 3.4.3.1 Edible cropsSalad crop growers are concerned over food safety and carry out more frequent supply water analysis than growers of ornamental crops. This also includes some microbial testing of water. Growers are very concerned about disease risks in recycled water, even to the extent of not using collected roof water, and therefore virtually no recycling is taking place.

Growers predominantly use public mains water, although some use borehole supplies and a few collect and use roof water from glasshouses. More reservoirs are in use in the north and west where rainfall is heaviest.

Most crops are harvested without any need for washing before marketing. The only exception to this would be washing of glasshouse radish after trimming and prior to packing. Washing of baby-leaf and mixed leaves for salad packs is considered to be carried out post “farm-gate”.

3.4.3.2 Ornamental cropsWater source is the public mains supply on many nurseries, with some use of borehole supplies and roof water. There is some concern over disease risks which may arise from water re-use. Recycling of water is mainly seen in ebb/flood bench systems in pot plant units. Some pot plant nurseries use automated pot washing lines for cleaning plastic pots before marketing, and some of this water is recycled. Unlike the edible crops sector there is more use of reservoirs in the south and east of England.

3.4.3.3 Protected crops - generalIt is recommended that growers store at least 3 days’ water supply to cope with contingencies, but only around half of the growers surveyed could meet this condition. On many glasshouse nurseries, space for storing water is at a premium, and apart from on some new sites there is no room to build a reservoir.

Roof water is a resource that most nurseries could have access to if suitable systems for capturing it were in place. Rainwater is generally high quality and if the system linking its collection to the irrigation system is clean and sealed, then it may not be necessary to treat this water, depending on the type of crops being grown. In some cases, planning authorities will only grant planning permission for new glasshouses if the applicant agrees to collect roof water in a “buffer” or “balancing” reservoir. This had been the case for around 1 in 6 of the nurseries audited but many more may find this to be a requirement when they make applications to construct new glasshouses in the future.

Collecting and storing roof water for irrigation obviously depends on rainfall, but also on the seasonality of cropping and evaporation rates from the surface. The following calculation shows that given adequate storage facilities, with average rainfall, a glasshouse nursery could be virtually self-sufficient in irrigation water requirement (example for Yorkshire):

1. Glasshouse roof area (m2) x annual rainfall (mm) / 1000 = potential water volume collected (m3).2. Thus with an annual rainfall in Yorkshire of 838mm, one hectare (10,000 m2) of glass would yield 10,000 x

838 / 1000 = 8,380 m3.3. On average, ornamentals use in a year 0.55 m3 of water per m2 (from survey) or 5,500 m3/ha. The rainfall

therefore more than covers the crop requirement.

3.4.3.4 MushroomsMushroom growers are very wary of possible crop disease implications from non-mains water, as well as food safety issues, so most use mains sources in production. However, compost producers tend to use water abstraction from rivers, with back up from reservoirs during the summer. Very little storage takes place for production, but composters will store in reservoirs.

3.4.3.5 Nursery stockWater source is the public mains supply on many nurseries, with some use of borehole supplies. Although some nurseries have substantial reservoirs, few are collecting rainwater from roofs or yards to supplement their use of mains water and roof water. Around a third of nurseries surveyed collected some roof water, but very few collected water from surface run-off, despite this being a cheap and plentiful source.

3.4.3.6 Bulbs and outdoor flowersIn the few instances where irrigation is needed, public mains water is used. In Lincolnshire, much of the abstracted water is saline and not suitable for flower crops such as gladioli which may require irrigation. As mains water is predominantly used, little storage is necessary.

3.4.4 Livestock usesWater for drinking and most yard washing is from public mains supply, though major users may have abstraction licences if the source of supply is of high enough quality.

4 CONCLUSIONS

4.1 Estimates of overall usage

The estimates of overall water use in England by the agricultural industry can be compiled from the above estimates for each sector. This has been done for each region within England (GOR) in Table 35 below, and indicates a grand total of some 300 million cubic meters of water annually, abstracted from both private and public sources. The regional analysis is made more difficult by mixing sources of information which record information in published documents according to different regional boundaries. Most of the values in Table 35 are estimates from recent reports and modelled approximations according to the currently used Government Office Regions (GORs) as they are expressed in Table 35. The irrigation statistics however, are expressed according to EA regional boundaries, which relate more closely with river basin districts within which water is gathered and abstracted. To enable the construction of a unified table a simple conversion has been employed on the regional values, which is pro rata with the differences in area of each region. This is done by “lending” and “borrowing” a proportion of the EA value to different GOR regions according to the areas that occur in alternative GOR boundaries. The resulting regional distribution is expressed for GOR regions in Figure 12, and for EA regions in Figure 13, though these latter values are incomplete because data are missing from the Midlands and EA Wales region which extend over both sides of the border between England and Wales, and some problem accounting for London.

Figure 12 Annual water use by agriculture according to GOR regions in England (M m3 a-1). The proportion of the total contributed by the three largest sector categories of field irrigation, all livestock and glasshouse and nursery crops, are shown.

The sector implications from Table 35 and Figures 12 &13 are quite clear, that the largest water use occurs because of the irrigation of major field crops during summer, and the other uses to wash and spray field crops are more minor components, with the exception of the water required for protected and nursery crops. The second largest usage is for livestock and rivals that for field irrigation, but shows the clear regional differences in agriculture across the country in Figure 12. Where arable agriculture predominates in eastern regions irrigation is by far the largest usage, whereas in western regions livestock are the greatest consumers, and this essentially means cattle, as other livestock are more evenly districbuted across the country (Table 35). These regional differences are not so readily apparent when analysed by EA boundaries, as these regions tend to be larger and spread over larger distances on an east-west axis. The exception is the Anglian region which is the largest. It also contains the vast majority of the irrigated area but relatively little livestock. In addition a proportion of the livestock usage is missing from Figure 13, as it couldn’t be assigned to an English region, but was located in EA Wales.

Figure 13 Annual water use by agriculture according to EA regions in England (M m3 a-1). The proportion of the total contributed by the three largest sector categories of field irrigation, all livestock and glasshouse and nursery crops, are shown.

One important aspect of this regional difference in sector requirements for water is the fact that livestock requirements will also be more evenly distributed throughout the year, although there will be a higher demand during hot dry weather in the summer. This temporal peak in demand however, will not be as marked as the fact that all the irrigation demand occurs during the main growth period in early summer, and in the most drought affected parts of the country. By far and away the most important water supply issue to deal with in agriculture is provided by field crop irrigation.

Table 35 Estimate of overall annual water use by agriculture (2006) by sector and region (GOR) throughout England (‘000 m3 a-1).

Government Office Regions (GOR) in England

East Mids

East London & S East

N East N West S West

West Mids

Yorks & Humber

Total England

Irrigation offield crops

29,415 45,554 22,533 3,344 1,019 5,248 13,025 7,955 128,093

Field crop spraying

551 800 363 108 75 301 269 390 2,857

Vegetable spraying (estimated)

40 89 10 8 9 13 14 15 198

Vegetable washing

28 48 19 1 18 8 73 11 207

Potato washing

6 8 1 1 2 2 4 3 26

Glasshouse use

1,250 2,560 3,400 120 1,680 1,440 1,140 1,730 13,320

Nursery use

3,990 8,360 11,870 680 2,640 3,740 6,340 2,890 40,510

Cattle 6,826 2,378 6,557 2,425 16,402 28,246 11,909 7,255 81,998

Pigs 796 2261 571 143 309 884 444 2,466 7,874

Sheep 1,383 384 1,543 2,103 3,260 3,680 2,556 2,363 17,272

Poultry 2,118 3,016 1,094 184 822 1,670 1,658 1,394 11,956

Total usage

46,403 65,459 47,961 9,118 26,236 45,232 37,431 26,472 304,311

4.2 Recommendations for Irrigation surveyGiven that the irrigation of field crops is the largest water use sector in the agricultural industry the accurate collection of data on the distribution of usage and quantities used on various crops is of paramount importance. Advice was therefore solicited from the last surveyors of this information, Cranfield University, as to what there recommendations to ensure and improve its collection would be. The following section are the recommendations from Dr E.K. Weatherhead of Cranfield University:

4.2.1 Data collection on irrigation water use in agricultureDeveloping policies on irrigation water use demands a knowledge of both existing water use and trends within the sector. To help target and evaluate policies, this should cover the headline figures – how much water is used – but also ideally which crops are irrigated, how much water is used on each, irrigation methods, water sources etc. Ideally the data would be available at regional or catchment level, and GIS mapped. However, the effort spent in collecting and verifying data needs to be commensurate with its usefulness.

There are two main data sources in England and Wales. Data on water abstracted for irrigation is available from the Environment Agency’s National Abstraction Licensing Database (NALD). More detailed data on irrigation practices is available from the periodic Defra-funded surveys of irrigation of outdoor crops.

All irrigators abstracting more than 20 m3 day-1 from surface or groundwater are required to have an abstraction licence, and to return data to the Environment Agency on the volumes abstracted, usually at least monthly, as a basis for water charges. Summary licence data, and some of the returns data, can be accessed later through the NALD database for research purposes. In theory this provides a complete database of both licensed and actual

water use. It is easily broken down to catchment level, based on the location of abstraction. In practice there are substantial problems using this data without detailed scrutiny of every entry, due to inter-linkages between licences, multiple errors due to alternate uses, missing data, and input errors. The data does not include water from other sources, e.g. from public water supply (significant in the south-east), rainwater harvesting, wastewater re-use, etc, and in future it will not include small abstractors (<20 m3 day-1).

The “irrigation of outdoor crops” surveys have been carried out periodically for many years. Since 1982 the main questions have been kept consistent, giving now eight sets of directly comparable data, for 1982, 1984, 1987, 1990, 1992, 1995 (all by MAFF), then 2001 and (shortly) 2005 (both for Defra by Cranfield University). The irrigation data are broken down between 8 crop categories, by area and volume. Other data includes irrigation method, water source, and scheduling method. These data are richer in content but less complete. The address list is from a trigger question in the annual Defra "Agricultural and Horticultural Cropping" census (the “June Census”). This is only a full census in selected years. Statistical corrections therefore have to be made for those not included in the June census, non returns to the June census, and non-returns to the (voluntary) irrigation survey. For 2001 for example, the final returns were estimated to cover about 40% of the total irrigated area. Note the survey data only refers to outdoor crops grown on registered agricultural holdings; it therefore excludes glasshouse crops, and landscape and other non-crop irrigation, but does include all water sources.

Data for particular or local purposes can be obtained from other sources, for example: Each EA CAMS ledger contains data on the local abstractions. Farmer-based abstractor groups collect selected data from their members; Industry surveys have been used for some smaller sectors, e.g. on the extent of trickle irrigation, for EA

R&D project W6-070, New authorisations for trickle; Crop-based organisations such as the British Potato Council, British Sugar and the Cambridge University

Potato Growers Research Association (CUPGRA) hold data supplied by members – however this is usually considered commercially confidential.

Generally, each data source is incomplete; together however they can be used to build an acceptable picture of the irrigation sector at national and regional level, At catchment level, actual abstraction data can become increasingly unreliable due to confidentiality restrictions and missing data.

Remotely-sensed data are sometimes suggested, as used in many arid locations. Resolution has been much improved (now <2m). It can provide useful data on crop location. However, under UK climatic conditions, it is still very difficult to reliably distinguish irrigated crops from non-irrigated crops of the same type, and the data would not indicate volumes or sources of the water used, nor the irrigation practices employed.

It is vital to remember that all data on actual abstraction and/or irrigation varies greatly with the weather in the particular year. Any derivation of trends must therefore either be over the long-term and/or take the weather variation into account. A methodology for this was developed and use by Weatherhead (e.g. Weatherhead et al., 2000)

4.2.2 Suggestions for future data collectionIt is assumed that Defra and the EA wish to retain a good understanding of how irrigation is changing nationally, supplemented by specific information in critical locations and/or sectors where problems arise.

The EA NALD data should increasingly provide an accurate picture of overall water use. However, it is not well structured for this purpose, and individual researchers are often having to repeat the same correction, probably using different assumptions. The EA should be encouraged to review the operation of NALD with relevant users/researchers, to make it more usable and more accurate.

The surveys of irrigation of outdoor crops has problems with non-returns, particularly since it became obligatory to make clear it was voluntary. However it forms an extremely important long-term dataset, and the only national information on crop types, irrigation methods, etc. The national and regional totals can be compared to NALD data to check the statistical corrections. It is recommended that the survey continue at roughly 3 year intervals, avoiding both extreme wet years (little irrigation) and very dry years (irrigation restricted). Timings should also coincide with the 10 yearly full June Census. Further updating of the questions could be considered, including refinement of the crop categories.

Linking the survey of irrigation of outdoor crops to the EA NALD information at individual abstractor/licence level has been attempted previously, with limited success. This is not a trivial task because of the different definitions and data sources, but it could be re- considered, particularly if the NALD database was improved. The EA do have powers to ask for the same information as part of the abstraction licence returns, and this could be useful locally, e.g. in over-abstracted catchments. However abstractors might be reluctant to give detailed information which could risk licence renewal. Use of a survey organisation (recently Cranfield University) independent from

both regulator (EA and DEFRA) and the abstractors helps allay potential respondent concerns over confidentiality and non-statistical uses of individual data, and should be continued.

In summary, a continuation of the periodic irrigation surveys is therefore proposed, along with improvements in NALD and the survey questions, backed up by more targeted local data gathering through licence returns and/or sector surveys as and when needed. This would provide a long-term national dataset and a “risk-based” approach to more detailed studies.

4.3 Further observations on the knowledge database of water use by agriculture.4.3.1 Irrigation All of the data used in this report is based upon estimates of the actual amounts used, made with varying degrees of accuracy and based on many disparate sources. The above comments about improving the surveying of field crop irrigation are extremely important as this is the largest single use by the agricultural industry. It is also based on one of the more reliable sets of data, but even this is only based on a response of 41% of a survey of 5603 holdings (55% of irrigated area). This represents a drop in response on the previous survey of 78% from 7800 holdings, which is actually only about one third of the previous numbers of reports (2297 cf. 6084). There must inevitably be greater error associated with the volumes and areas of irrigation from the last report (Weatherhead & Danert, 2002) compared with previous reports, which formed part of a more regular programme of data gathering. This situation may improve if more regular surveys are once again instigated, and/or associated more closely with more stringent census data gathering.

An improvement in knowing the actual usage is highly desirable. Past estimates have been used to predict future requirements, but highly erroneously it turns out. The main error has however, been a misjudgement of how the market for produce may change rather than the estimates of usage per se. Water use errors become magnified however, if an unwarranted growth of any particular sector is envisaged, such as occurred for the early-potato, vegetables and sugar beet sectors in the 1970s. More recent predictions use better market led models (Figure 4) but will have to include the more vaguely understood changes due to be caused by climate change.

To assist planning of water provision more successfully in the future, when evaporative demand is due to rise (25% in the Thames water basin), and summer rainfall decrease (by 10-20% in the same region), better estimates of actual demand at more local scales, will be necessary. These will have to account of interactions with soil type, as demand will increase proportionately more for lighter sandy soils with lower water holding capacities.

4.3.2 Spray volumes for field cropsThe quality control of the pesticide use data used to derive volumes of water used in pesticide spraying programmes, is probably the best of all the information used (Garthwaite et al., 2005). However, it is based on even fewer survey responses than the irrigation data, 965 in 2004 (Garthwaite et al., 2005) representing only 4% of UK agriculture. It is also founded on average volumes of water used for different products and numbers of applications, and hence cannot accurately portray any variance in these with region or short-term changes in the market for products.

The greatest omission in the dataset though is undoubtedly the fact that field vegetables are not included in the survey, and these are thought to be of a similar impact to the area of potatoes (a large spray usage). Future estimates could be greatly improved by extending the surveys to include this sector.

4.3.3 Washing of field vegetables and protected cropsThe data for water used in vegetable washing are genuine estimates, as this is not recorded, either on site or as surveys of growers, but nevertheless is considered to be at least as accurate as the above survey data. This is because it is based upon fairly robust knowledge of how much water is used by washing processes (it is often metered) and good statistics about how much produce is grown. However, it could be greatly improved by inclusion in a census, as the information is likely to be recorded by growers for financial reasons, as the water is often taken from the public supply.

Although the data for protected and nursery crops are taken from a fairly robust survey specifically for a water audit, they come from a ”one-off” event of a limited nature. As for the washing of vegetables, water is often taken from public supply for health reasons in this sector and so should be in a readily collectable format for more regular monitoring via surveys or census. This would be highly desirable as usage figures can be established more firmly from several years returns, with the additional benefit of trends being identified, for what is the third largest usage sector overall.

4.3.4 Livestock sectorThe data from the livestock sector are again true calculated estimates, being derived from “typical” amounts used per livestock unit and most recent census data of animal numbers. As can be seen from Tables 25-27 these

estimates are only achieved after some fairly complex calculations for the pig and poultry data, and no actual survey of use has been carried out. Growers of livestock reared in more intensive systems, such as dairy, pigs and poultry, often have a good record of how much water they actually use, and this could be gathered in a more formal survey or census system. Extensive cattle and sheep however, would not be so easily accommodated.

4.3.5 Regional variationsThe first point to make about making regional estimates of water use, is that data are not reported according to standard geographic units. Depending upon the source of data either Government Office Regions (GORs) or Environment Authority (EA) boundaries are used to delineate the region reported on. The EA boundaries follow geographically logical water catchment and river basin boundaries, whereas GORs are politically determined units of accounting. In this report only the irrigation surveys actually gather data according to EA regions, whereas all the other datasets come from information recorded in GORs. In this report a rough conversion has been used to adjust figure pro rata from one system to the other, but if the data are actually held at county level then it is believed the two systems can be adjusted more accurately from one to the other. It is therefore recommended that in future, survey and census data are collected and held at a sufficiently small scale that it can be displayed according to either regional boundary system.

A clear regional bias is seen in the current burden of water supply for agriculture, towards the eastern regions being more heavily impacted than others. The largest overall water use of field crop irrigation is highest in the GORs of Eastern England and East Midlands, whilst other arable uses of pesticide spraying and potato and vegetable washing are also concentrated in the same eastern regions. Significant numbers of pig and poultry units are also located in these regions. There is therefore already a disproportionate burden placed upon water supply in these two regions, which is likely to increase simply from the continued trend of increasing irrigation use for potatoes. In addition irrigation and crop spraying are concentrated into the summer months at a time of year when climate change is forecast to lead to reduced surface water supply from rainfall during this period. The abstraction and supply of water around 2020 will therefore have to be an extremely tightly managed activity.

Protected and nursery crops are also a major consumer of water from the public supply, and regionally concentrated in the heavily populated and relatively dry South East of England, with significant use in the Eastern region and both Midlands regions. There is little change in the size or distribution of the protected crop industry due to climate change, except that it may become profitable in Northern regions with warmer temperatures, and so the current pressure on water abstraction in the South East is likely to be maintained.

The highest livestock use of water is in the cattle industry (dairy and beef) and concentrated quite clearly in the South West Region, where it far outstrips irrigation in the amount used. Other regions where it outweighs irrigation for volume used, are the North West and West Midlands. However, its use is spread evenly through out the year, and in regions where little reduction (if any) in surface water supply is forecast. If the current trend of contraction in the dairy industry continues, then there seems that there will be little extra burden for water supply in 2020 by the cattle industry.

References to published material9. This section should be used to record links (hypertext links where possible) or references to other

published material generated by, or relating to this project.Anon. (1998) The Water Code (Revised 1998). Code of Agricultural Practice for the Protection of Water.

MAFF Publications PB0585.Anon. (2002) Red meat safety and clean livestock. Published by Food Standards Agency, London. 2K

FSA/0595/0602BETA. (2006) National Equestrian Survey. Publ., British Equestrian trade Association. http://www.beta-

uk.org (last accessed 11/09/06)Bryson, T. (1984). The sheep housing handbook. Farming Press Ltd., Ipswich. ISBN 0 85236 1327.Burton M. P. (1992) An Agricultural Policy Model for the UK. Avebury.Defra (2005a) e-Digest of Environmental Statistics, Published December 2005.

http://www.defra.gov.uk/environment/statistics/index.htmDefra (2005b) Annual Crops Survey December 2005. Publ. Defra Farming Statistics, York.Defra (2006a) Defra Glasshouse Survey (England & Wales) January 2006Defra (2006b) Basic Horticultural Statistics 2006 (calendar years 1995-2006). Publ. Defra Farming

Statistics, York.Downing T.E., Butterfield R.E., Edmonds B., Knox J.W., Moss S., Piper B.S. & Weatherhead E.K. (and

the CCDeW project team)(2003) Climate Change and the Demand for Water, Research Report, Stockholm Environment Institute Oxford Office, Oxford. 201pp

Environment Agency. (2003) Optimum use of water for industry and agriculture: phase 3. Best Practice Manual. R&D Technical Report W6-956/TR2. Agricultural components – Weatherhead, E.K., Knox, J.W., Twite,C.L. and Morris, J. SRK Consulting and Cranfield University.

Environment Agency (2006) The Water Act 2003. Modernising the regulation of water resources. Leaflet published by EA, Bristol, UK. (http://www.environment-agency.gov.uk/commondata/acrobat/water_act_leaflet_833646.pdf)

Garthwaite D.G., Thomas M.R., Dawson A. & Stoddart H. (2003). Pesticide Usage Survey Report 187: Arable Crops in Great Britain 2002. Publ. Defra Publications, London.108pp.

Garthwaite D.G., Thomas M.R., Anderson H. & Stoddart H. (2005). Pesticide Usage Survey Report 202: Arable Crops in Great Britain 2004. Publ. Defra Publications, London.113pp.

HCIC Horticulture Crop Report. published monthly Publ. Defra Farming Statistics, York.Hulme, M., Jenkins, G.J., Lu, X., Turnpenny, J.R., Mitchell, T.D., Jones, R.G., Lowe, J., Murphy, J.M.,

Hassell, D., Boorman, P., McDonald, R. and Hill, S. (2002) Climate Change Scenarios for the United Kingdom: The UKCIP02 Scientific Report, Tyndall Centre for Climate Change Research, School of Environmental Sciences, University of East Anglia, Norwich, UK. 120pp.

Knox J.W., Weatherhead E.K. & Bradley R.I. (1997) Mapping the total volumetric irrigation water requirements in England and Wales. Agricultural Water management, 33:1-18

Knox, J.W. & Weatherhead, E.K. (2003). Trickle Irrigation in England and Wales. R&D Technical Report W6-070/TR (also R&D Technical Summary W6-070/TS). Environment Agency, Bristol.

Knox J.W. & Weatherhead E.K. (2005) The growth of trickle irrigation in England and Wales: Data, regulation and water resource impacts. Irrigation and Drainage, 54:135-143

Laws, J.A. and Chadwick, D.R. (2006) Characterisation of cattle slurry management strategies to reduce the amount produced on UK dairy farms. Bioresource Technology. In press.

MAFF (1997) Survey of irrigation of outdoor crops in 1995 England. MAFF Statistics 222/96 (Amended).Smith, K.A., & Frost, J.P. (2000) Nitrogen excretion by farm livestock with respect to land spreading

requirements and controlling nitrogen losses to ground and surface waters. Part 1: Cattle and sheep. Bioresource Technology 71, pp 173-181.

Smith, K.A., Charles, D.R. & Moorhouse, D. (2000) Nitrogen excretion by farm livestock with respect to land spreading requirements and controlling nitrogen losses to ground and surface waters. Part 2: Pigs and poultry. Bioresource Technology 71, pp 183-194.

Strutt N. for Advisory Council for Agriculture and Horticulture in England and Wales. (1980). Water for Agriculture: Future Needs. Publ. MAFF, London. 72pp

Weatherhead E.K., Place A.J., Morris J., Burton M. (1994) Demand for irrigation water. National River Authority R & D report No. 14, HMSO, London.

Weatherhead E. K. & Danert K. (2002). Survey of irrigation of outdoor crops in 2001 – England. Cranfield University, Silsoe.

Weatherhead E. K. & Knox J.W. (2000). Predicting and mapping the future demand for irrigation water in England and Wales. Agricultural Water Management, 43: 203-218.

Weatherhead, E.K, Knox, J.W and Morris, J. (2000). National and regional water resource strategies: forecasting spray irrigation demand 1997-2024/25. Final Report to Environment Agency. Cranfield University, Bedford

http://www.environment-agency.gov.uk/commondata/acrobat/water_act_leaflet_833646.pdf

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