low cost irrigation

8/17/2019 Low cost irrigation

1/7

International Water Management Institute

23

Low-cost irrigation for poverty reduction

An evaluat ion of low-head drip irrigation technologies in Kenya

S.N. Ngigi, J .N. Thome, D.W. Waweru, H.G. B lank

Low -head irrigation technologies w ere introduced in Kenya in 1995 by Christian M ission

Aid. The Kenyan Agricultural Research Institute (KA RI) has been prom oting the technology

since 19 96.

U ntil recently, Kenyan sm allholders, m ostly w om en, struggled to m aintain kitchen gardens,

using hand-w atering to cultivate vegetables for their fam ilies. H and-w atering of vegetable

gardens is tedious and inefficient especially w here w ater is scarce. It requires m any trips

back and forth to the w ater source (w hich is often som e distance aw ay), and it does not

deliver w ater dow n to the root zone (Reaves 1995). Rather than go through this tedious

and tim e-consum ing irrigation process, m any people chose to go w ithout vegetables in

their diet during the dry season.

Today, they use low -head irrigation technologies in the form of bucket drip kits to deliver

w ater to their crops effectively, w ith far less effort and for a m inim um cost. H undreds of

poor fam ilies that use bucket kits during the dry season have show n that it is possible to

produce enough vegetables for their dom estic use and even for sale (Lusaka 1999).

U se of the drip kit is spreading rapidly in Kenya and the m ajority of drip users (som e 70-

80% ) are w om en (W inrock 2000). W om en do m ost of the gardening in K enya, and w ould

often carry w ater from distant w ater sources to hand-w ater their vegetables.

Summary

Unreliable ra infall causes periodic droughts in Kenya. This unpredicta bility, coupled

with the lack of local capacity to deal with the situation, creates a persistent threat

of household food insecurity in the region. Low-head drip irrigation technologies

were introduced to combat this problem and alleviate food insecurity for thousands

of people. First indications from a variety of research sources are that these tech-

nologies a re a formidable poverty-fighting tool.

IWMI research evaluated the low-head drip systems most commonly available in

Kenya. The purpose of this resea rch wa s to identify and a ddress the technical con-

straints of the systems and to develop practical recommendations for smallholder

farmers, so that they can maximize the benefits of this technology.


2/7


24

Low head drip irrigation technology: Advantages and disadvantages.

W ater saving—a large reduction in the

am ount of w ater needed for grow ing veg-

etables

Lab or saving—plots can b e irrigated

quickly, sim ply by filling the bucket

Few er disease problem s, such a m old and

pow dery m ildew (fungal), caused by soil

splashing onto plant leaves (Baobab 1998)

Low -cost—the system is priced to fit poor

farm ers’budgets

Sim ple to install, operate and m aintain

Easy to adapt to m eet farm ers’particular

needs; for exam ple, O uko (1998) reported

that som e farm ers in the S uba district

along Lake Victoria, are fixing 30-m drip

lines (rather than the usual 15 m ) to larger

50-liter buckets to accom m odate longer

grow ing beds

Profitable for sm all-scale farm ers—en-

abling them to produce enough vegetables

for their fam ilies and for sale

Advantages Disadvantages

Breakage of the filter plug due to brittleness of the

plastic used

Less flexibility in term s of em itter spacing and lateral

lengths

Easily punctured by sharp objects if poorly handled

Clogging of som e em itters

N onuniform ity of em itter discharge along the lateral,

especially w here land is not w ell leveled

Lack of spare parts and inadequate extension services

Leakage, especially at bucket connections, if fittings

are not done properly, i.e., if the hole is bigger than

the adapter; other causes of leakage are punctures,

cracks.

Insecurity: fear of theft if the system is installed far

from the house

Pest attraction—being the only green spot, especially

during the prolonged dry spells, insects, rodents,

aphids, etc., find refuge in the drip gardens; porcu-

pines in search of w ater have even been reported to

puncture drip lines in the Suba district (O uko 1998)

Improved household nutrition and incomes

D rip kits do have disadvantages (see box) but the positive socioeconom ic im pacts seem to

outw eigh them . Farm ers reported gross profit m argins ranging betw een Ksh. 4,000-10,000

($80-200) w ith a single bucket kit per season, depending on the type of vegetable (W inrock

2000), and betw een K sh. 20,000-30,000 ($400-600) per season w ith the 1 /8 acre kit

(N yakw ara et al. 2000; W inrock 2000). These kits enable farm ers to grow high-value crops,

and they create em ploym ent opportunities in the rural areas. This adds up to a significant

potential for poverty alleviation.

Take the case of M rs. M utai (KARI 1998). She is one of 15 0 w om en w ho w ere m em bers

of a group that started using drip irrigation in Eldoret. The system w as installed in D ecem -

ber 1996. Four m onths later, she had already sold enough vegetables to invest in m ore

lines and m ake her garden bigger. Another m em ber of the w om en’s group, Anne Butia,

has sold K sh 10,000 ($200) w orth of vegetables in three m onths from her tightly-fenced

garden. N eighbors used to w alk 1 0 kilom eters to another district to buy vegetables but

now they buy them from her. She has used the extra incom e to pay school fees and buy

clothes for her fam ily.


3/7


25

These and other cases show that low -head drip irrigation is proving to be a prom ising

technology for responding to shortages of w ater and food in arid and sem iarid areas. Low -

head drip irrigation technologies prom ise im proved food security and increased incom es at

the household level, ultim ately culm inating in a healthy national econom y (W inrock 2000).

N diritu (1999) goes further, saying that “the bucket kit is the sal-

vation of our country, as it allow s the poorest of the poor to pro-

duce vegetables under conditions that previously w ould have only

produced starvation and death.”

Types of low-head drip systems

W ith low -head drip irrigation the o versophisticated an d

overengineered control elem ents used in the conventional drip sys-

tem s are m inim ized and replaced by sim ple do-it-yourself equip-

m ent—low -head drip irrigation technologies.

Low -head drip system s operate under pressures of 0.5-2 m w ater

head com pared to the 10-15 m w ater head needed for standard

drip irrigation (G ilead 1985). Sm all reservoirs such as oil drum s

can be used as header w ater tanks. These are supported on blocks

so that the w ater pressure falls w ithin the required range. Perfo-

rated flexible plastic piping conveys w ater to the plants. Low -head

drip irrigation technologies includes gravity drip irrigation and bucket

and drum kits.

Gravity drip irrigation

G ravity drip irrigation m akes use of very low pressures. It fits into

the infrastructure of existing channels, ditches and gravity-irrigated

fields. D ue to the low pressures, the system is very sensitive to

ground elevation differences and special drip laterals operating un-

der the above-m entioned condition are used (Gilead 1985).

The low operating pressure has m any advantages for the design of

gravity drip irrigation. These include:

Enables substantial enlargem ent of the cross-section of the laby-

rinth flow passage of each em ission unit, w hich sim ultaneously

w ill m inim ize or even avoid clogging.

Translating research into practic

for farmers

From science to smallh

‘ Smallholders’ are thosemen farmers who use raisometimes irrigation watcrops on their own land, rencommon ground. The majoers in developing cousmallholders. Many of them

land and water and little or no money or creditand they are not empowered to participate in mat village or district level. Smallholders often havbut to exploit their land and water resources ilead to widespread and serious environmental

Hun d r e d s o f m i l l i o n s o f sma l l h o l d e

benef i t f rom past research on land and wat

ment because they do not kn ow about i t , an

recommendat ions are too vague, too ls are t

t i ca l o r so lu t ions too expens ive . Yet mu

knowledge and expertise does already existlenge before us is to bring practical knowledgful tools from research to the minds and han

farmers. Through IWMI’s research on smallholwater management, we work for rural smallfarm sloping lands, for those that have no ch

farm old, infertile soils in the upland parts of and for farmers who are trying to make ends murban areas.

Water and nutrients from the soil are essencrops. Providing an adequate balance of thmaximizes the efficiency of investments in bot

Our research goal is to produc e more a

know ledge and bet ter-adapted too ls specsmal lho lders , to help them achieve the optimnutrient balance—consistently and on a long-tArmed with these improvements, farmers cawater and land resources more effectively and able returns on their investments. This increacome and encourages investments in natural to make their use sustainable.

To achieve this goal of putting practical inteof our research into millions of smallholder farmrequires considerable ‘ reach’ . We are doing ing partnerships with National Agricultural ReExtension Services (NARES), whose task is tothis. We are developing recommendations anNARES, testing and improving them with the hers, and supporting NARES in their efforts to dthe results to smallholders and this synergy wiconditions that substantially improve the wmany smallholders, and make use of naturasustainable.

○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○ ○

Dr. Frits Pen ning de Vries, is the lead er of IWMI’s them e

sustainable smallholder water and land management s


4/7


26

The drip rate can be reduced dow n to 1.2l/h/m , despite the large flow passage.

Low er drip rate m eans larger lateral lines and diam eter reduction of the distribution

and m ain lines and also of the other control elem ents.

It enables use of a lateral produced from a very thin but still very strong plastic film

m ade from a specially tailored polym er, w hich helps to reduce gravity drip irrigation

lateral costs to a m inim um .

O ptim al grow ing conditions can be achieved because the very low drip rate enablesround-the-clock irrigation at peak season.

Advances in drip irrigation technology have m ade it possible to develop a sim ple bucket/

drum kit system that low -incom e fam ilies can afford (produced by Chapin W aterm atics).

For several years, bucket kit drip irrigation has helped thousands of fam ilies provide fresh

vegetables for their fam ilies. It has proved especially useful in w ater-scarce areas w here

w ater has to be carried for long distances—requiring that every drop is used in the m ost

efficient w ay possible.

Chapin KARI, FPEAK 30 0.25 16.0 950 per kit ($19)

T-Tape 520 B ooth 20 0.50 16.0 12 per m eter ($0.24)

Typhoon 25 Am iran 40 0.63 15.4 16 per m eter ($0.32)

Victoria ShadeN et Ltd. 30 0.50 16.0 9 per m eter ($0.18)

W aterboys KARI, for 30 0.15 16.0 2,800 per kit ($56)

dem onstration

Overview of drip kits and lines available in Kenya.

In Kenya, this sim ple technology is being prom oted by K ARI and the Fresh Produce Exporters

Association of Kenya (FPEAK) in cooperation w ith C hapin Third W orld Projects. The system

is gaining popularity and is being used by m any fam ilies in the Eldoret, N gong, and Kajiado

districts in the Rift Valley province; Gatundu and N deiya-Karai in the Central province; Tharaka,

M achakos and Kitui in the Eastern province, and in m any other drought- prone areas. In

addition to Kenya, the bucket kit has also been im plem ented in Zam bia, M ozam bique, M alaw i,

Sw aziland, South Africa, N am ibia, U ganda and N igeria (Chapin 1998).

Bucket and drum drip kits

The bucket kit is a sm all-scale drip irrigation system w ith high w ater use efficiency that

operates at low pressure heads of 0.5 to 2.0 m (0.05-0.2 bar). It consists of a 20-liter


5/7


27

bucket or a 200-liter drum , drip tape, filters, rubber w ashers, m ale and fem ale adapters,

tw o supply tubes and barb fittings. A 0.75-inch screen filter w ith a flow ranging from 0.9

to 2.5 m 3/h is provided w ith the drip kit.

The bucket is m ounted on a stand, w hich holds it one m eter above the ground. The drip

lines are supplied in lengths of 15 m , and, for best results, they are laid on level ground.

If the drip lines go up a sm all slope, the bucket or drum should be placed on the highest

side. The lines are laid w ith the em itters facing up to reduce the problem of sedim ent

settling on the em itters. In the case of the drum system , the drum is connected to a m anifold

w ith five openings, each located to cover a bed. The m anifold includes a PVC pipe, bends,

gate valve, tees, and glue for fitting.

Comparison of the available drip lines in Kenya

There are m any suppliers of different com m ercial drip system s in Kenya. The m ajority of

existing drip lines are designed for high-pressure system s. There are few specifically de-

signed low -head drip lines. These include Chapin, T-Tape and W aterboys. IW M I research

evaluated these, and the m ost com m only available high-head drip lines for use w ith low -

head system s.

Tw o com m on problem s experienced by farm ers using low -head drip system s are uneven

w ater distribution, especially on sloping land, w hich can drastically affect yields due to

under-irrigation of som e plants and over-irrigation of others; and the tendency of em itters

to clog. IW M I research tested existing low -head drip irrigation system s in an effort to over-

com e or at least m inim ize som e of these constraints.


6/7


28

Recommendations for farmers using low-head drip systems

Readily availabl e high-head drip lines can be adapted for use with low-head systems.

In addition to Chapin system drip lines, the existing high-head drip tapes, e.g., Typhoon,

T-Tape and Victoria, can be used for low -head (as low as 0.5m ) bucket kit system s w ith-

out substantially affecting perform ance (w ater distribution uniform ity along the drip tape

for various supply head, lateral length and land slope). This m eans low -head drip kits can

be assem bled locally w ith readily available high-head drip tapes and fittings.

Land slope has more eff ect on water distributi on unif ormit y than either head or lateral

length. D ifferent drip tapes perform differently w ith respect to the three param eters evalu-

ated—land slope, lateral length, and w ater supply head. Thus discharge rates vary w ith

head, slope, lateral length and type of drip tape. W ater distribution uniform ity decreases

w ith the lateral length, though different tapes perform differently, e.g., for T-Tape, length

increases beyond 20 m have no significant effect on w ater distribution uniform ity. Although

w ater supply head seem s to have no significant effect on w ater distribution uniform ity,

there is a slight im provem ent w ith increase in head, especially for high-head-designed tapes.

The effect of head is significant for sloping land. H ow ever, land slope has m ore effect on

w ater distribution uniform ity than either head or lateral length.

The effect of land slope on water distribution for Victoria driptape.

To adapt to the performance variati on between the two drip li nes of a kit , farmers should

grow crops with higher water demand on the side of the higher performi ng line. W ater

distribution varies betw een the two drip lines of the bucket kit. The difference in perfor-

m ance could be attributed to either one line being a bit low er than the other, m ore leak-

age on one line or m ore clogging on one line. These factors could lead to pressure differ-

ences and hence the variations in w ater distribution. Farm ers can adapt to this difference

by grow ing the crops w ith higher w ater dem ands on one side.


7/7


29

For sloping land, the bucket should be placed up-slope; the crops with t he highest

water demand should be planted down-slope. W ater distribution uniform ity decreases

w ith an increase in land slopes, w hether up-slope or dow n-slope, but dow n-slope drip

kit layout gives a better w ater distribution uniform ity than up-slope layouts. If land is

sloping, as is norm ally the case, it is advisable to place the bucket on the higher side,

i.e., dow n-slope. For sloping land, high w ater-consum ption crops should be planted

on the dow nstream side w hile less w ater-consum ing crops should be planted upstream .

Impli cations of combi ning any two parameters. The com bined effect of any tw o pa-

ram eters: w ater-supply head and land slope, w ater supply-head and lateral length, and

land slope and lateral length revealed that:

It is not advisable to use longer lengths (beyond 7.5 m ) for sloping land.

It is advisable to use higher head (1.50 m ) for longer lateral lengths.

W ater uniform ity distribution im proves significantly w ith increase in supply head

for sloping land, especially for up-slope layout. U p-slope layout is recom m ended

w ith high w ater supply head.

Filters can be improv ised out of common household materials to prevent emit ter clog-

ging. To im prove w ater distribution uniform ity, a filter w hich is an im portant com po-

nent of the drip kit, is used to prevent em itter clogging. W aterboys, w hich have no

filter, seem to be prone to clogging. Locally available “filter”m aterial, e.g., used lady’s

stockings, m osquito nets, etc., can be im provised as a form of ‘jua kali ’filter.

S.N N gigi, J.N . Th om e, and D .W . W aw eru are from the U niversity of N airobi’s D epartm ent of Agricultural En gineering;H .G . Blank w as IW M I’s regional representative in Eastern Africa u p u ntil August 20 00.

This research is part of a series of projects and investigations by IW M I and its partners, exam ining various aspects ofsm all-scale and inform al irrigation in southern and eastern A frica.

The research w as carried out with support from the African D evelopm ent Bank.

REFERENCES

Chapin, R. D . 1998. Bucket kit new s.

G ilead, G . G . 1985. G ravity D rip Irrigation (GD I) System . Proceedings of the Third International D rip/TrickleIrrigation Congress. California, U.S.A. ASAE Vol. II.

KARI. 1998. Sim ple drip irrigation m akes a big difference on sm all farm s.Harambee- pulling together forKenya. A report of the Kenya N ational Research Project. KARI, N airobi.

Lusaka, N . 1999. Bucket kits in K enya. Bucket Kit N ew s, Chapin Living W aters Foundation. U npublishedreport.

N diritu, C. 1997. Q uoted from Chapin Living W aters Foundation B rochure.

O uko, B. 1998. Kenya Islands M ission D rip Irrigation Program m e. Proceedings of W orkshop on Sm all-ScaleD rip Irrigation Experience Sharing W orkshop. 28 -30 Septem ber, 1998, Kitui Kenya.

Reaves, R.E. 1995. Third w orld faith in action. Irrigation Journal 45(6). Adam s Trade Press.

W inrock. 2000. Proceedings of Low -H ead D rip Irrigation Review W orkshop. 17-18 February, 2000, N airobi,Kenya.

low cost irrigation

Documents