managing soil fertility - teagasc · 2019-06-25 · 3 soil fertility data teagasc analyse c. 35,000...

Managing SoilFertility

Teagasc Soil FertilityManagement

Spring 2015

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Outline – Key Questions

What’s happening to soil fertility ?

What steps can be followed to manage it ?

What are the benefits ? Is there a return on investment to

managing / improving fertility ?

What Targets can be set for soil fertility ?

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Soil Fertility Data Teagasc analyse c. 35,000 samples per year

Individual results never disclosed to third party

Database provides good overview of national soilfertility

Not a random sample

Not fully representative

Not validated

Gives overview

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Lime Usage in Ireland

Source : DAFM

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Soil pH – Grassland soils

Grassland target= 6.2-6.3

67% of grassland soilswith pH < 6.2

Liming is very important

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Soil pH –Tillage soils

Tillage crop target= 6.5

61% of tillage soils withpH < 6.5

Liming is very important

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National Fertilizer Usage 1998-2011

N

P

K

0

50

100

150

200

250

300

350

400

450

5001998

1999

2000

2001

2002

2003

2004

2005

2006

2007

2008

2009

2010

2011

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0

20

40

60

80

100

120

140

P&

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Fertilizer N P K Usage in Ireland

DAFM

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Soil Test P & K – National (All)

What does this mean for you?

- ~ 24-28 % of soils are in Index 3

- If you don’t soil test, you don’t know what you are dealing with

- Are your soil fertility levels declining as well?

- You don’t know unless you soil test

Grassland Soils With Optimum Soil Fertility

9)

Tillage Soils With Optimum Soil Fertility

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Steps to Soil Fertility Management

Index Description

1 Very Low

2 Low

3 Target

4 High

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Steps to Soil Fertility Management

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Soil Testing – Why? Indicator of background soil fertility levels

Soil pH and Lime requirement P & K Mg and trace elements

Tool to help plan nutrient applications Fertilizer Slurry / FYM

Monitor change in soil fertility levels overtime Adjust fertilizer / manure management practices

Derogation requirement

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Soil Testing – How? Area: one sample per 2-4 ha (5 ha with derogation)

Soil type; slope; cropping history; drainage; experience

Practical management units

Sampling pattern:

Representative sample from entire field

Avoid unusual spots (Gates, Feeders, old fences, ditches, dung/urinepatches, FYM heaps)

Avoid lines of normal fertilizer / slurry application traffic

No. of cores:

Minimum 20 cores per sample

Mix and sub-sample cores if necessary

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Soil Testing – Sampling Depth Critical – especially for P

Permanent Pasture P tends to stay near the

surface

Full 10 cm deep samplingis critical Ground conditions @

sampling

Wear on soil corer

Regularly ploughed Less of an issue

Re-test after ploughing

Soil P level

So

ilD

epth

Soil P level

So

ilD

epth

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Soil test for ploughing / reseeding Permanent Grassland – P

concentrated in top few cm of soil

Ploughing – P displacement

Young seedlings High P requirement for

germination & establishment

P supply delayed until roots getdown

Soil sample after ploughing

Can be an issue for min-tillcrops as well – P concentratedat surface

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Soil Testing – When? How often:

Every 3-5 years (4 years ifin derogation)

Timing: For comparison, sample at

same of year

Avoid extremes (Very dry /waterlogged)

Late Autumn / Early Springideal Results ready for fertilizer

planning for the comingyear

Slurry / FYM

3-6 months

Fertilizer P & K

3-6 months

Lime

2 years

(for accurate soil pH)

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Soil Testing – Cost / Benefit

~ 25% of soils are in Index 3

If no soil test and assume Index 3, then youare likely to be wrong in 75% of fields !!

Cost

Consider relative to fertilizer cost?

= € 350-500 / tonne ???

N P KFertilizer

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Steps to Soil Fertility Management

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Soil pH and Liming

Optimum pH for grassland = 6.2 - 6.3 Maximum nutrient release from soils Soil biological activity

~67% of grassland soil < 6.0

Response to fertilizer P on acid soils ????

6.54.5 7.05.0 7.55.5 6.0

P

N

K

• Soil P reserve lessavailable

• Fertilizers lessavailable

Lime in grassland

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1 ha

Up to 250-625 kg/ha/yr of limein drainage

100 kg=

180-220kg lime

Nfertiliser

Offtake1 bullock

25 kg of Lime

1,000 L milk3kg of lime

5 t/ha silageDM

75 kg of Lime

Grassland Example

150 kg/ha N – 300 kg2 bullocks – 50 kg

Lime loss in drainage – 250-625 kg

Total lime required –600 – 975 kg/ha/yr

1-2 ton/acre every 5 years

Lime and P availability

Average change in soil test P (Morgan’s) across 16 soils treated with P (100 kg/ha ofP), Lime (5 t/ha of lime), and P + Lime and incubated over 12 months in controlledconditions.

1. Lime increasedthe STP

2. Additive benefitsof P and lime

Sheil et al, 2013

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Lime requirements Advice is to apply lime in a 3-5 year cycle

Grassland typically requires between 0.5 - 1 t/ha/yr

Exceptions

High Mo soils and grassland don’t exceed pH 6.2

Lime requirements reduced by 5 t/ha

Where advice is > 7.5 t/ha

Split application

7.5 t/ha now

Remainder after 2 years

Precaution to reduce risk of trace element problems

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High Mo – higher risk where: High soil pH (>6.2)

Avoid over-liming

Poor drainage (or wetweather)

Species: Clover > Yorkshirefog > Meadow grass >Fescue > Timothy

Low Nitrogen inputs (Higher N higher yields Dilution of Mo in herbage+ less clover)

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Lime types Ground limestone

Apply as per Lime requirement

Calcium based Standard product

Magnesium based Use where Magnesium in the soil test is low

Granulated limes Same material, just more finely ground

More expensive Quick fix (e.g. tillage crops after sowing)

Rented ground

GranulatedLime

50 kg

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Lime Quality Quality Standards in place for Ground Limestone (SI 248

of 1978)

Statement should contain the following details:

Criteria Minimum standard

Fineness - 100% must pass through 3.35mm sieve

- 35% must pass through 0.15 mm sieve

Moisture Content - Must be < 3%

TNV(Total Neutralising Value– a measure of thestrength of the lime)

- Must be > 90%

27)

Lime for reseeding

Incorporate lime into theseedbed

Apply after ploughing (or afterspraying if direct drilling)

Till the lime into the soil

Avoid applications over 7.5t/ha (3 t/acre)

Where more lime required,wait 2 years to apply more lime

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Steps to Soil Fertility Management

Index Description

1 Very Low

2 Low

3 Target

4 High

29)

P & K

Convert test result into soil Index

Target = All soils in Index 3 for P and K ! Only ~ 25% at present

Soil Index Description Soil test P(mg L-1)

Soil test K(mg L-1)

1 Very low 0 – 3.0 0 – 50

2 Low 3.1 – 5.0 51 – 100

3 Medium 5.1 – 8.0 101 – 150

4 High ≥ 8.1 ≥ 151

Soil Index Description Soil test P(mg L-1)

Soil test K(mg L-1)

1 Very low 0 – 3.0 0 – 50

2 Low 3.1 – 5.0 51 – 100

3 Medium 5.1 – 8.0 101 – 150

4 High ≥ 8.1 ≥ 151

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Soil Fertility Week(4-8 February 2013)

Build up

Build up

Maintenance

Replaceofftake

Maintenance

Replaceofftake

Maintenance

Replaceofftake

Soil Index & Advice

Soil Index

1 2 3 4

Nutrientofftake

Advice

TargetIndex 3:Maintainbalance

Index 4:Draw on

soilreserves

Index 1 & 2:Requires additionalnutrients to build soil

reserves

31)

Maintenance rates – P & K offtakes

P (kg) K (kg)

Milk (1000 litres) 0.9 - 1 1 - 1.5

Liveweight (100 kg) 1 0.5 - 1

Silage (1 ton DM) 3 - 4 25

Leaching (1000 mm rainfall) ~ 10

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Soil P and K build up - GrasslandP K

Index 2

10 kg/ha

(8 units/acre)

30 kg/ha

(24 units/acre)

Index 1

20 kg/ha

(16 units/acre)

60 kg/ha

(48 units/acre)

16% P

25 kg

16% P

50 kg

Muriate50% K

25 kg

Muriate50% K

50 kg

Apply build up +maintenance inIndex 1 and 2

Apply for 5 yearsor until soil testshows increase

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How long does it take to change Index ? P

Normally takes a number of years to increase/decrease

Lighter soils tend to move faster Lower organic matter

Less clay

Advice Apply fertilizer as per soil test for a number of years

Re-test every 3-5 years to monitor changes over time

K Will change more quickly than P

Index 1 & 2 Apply maintenance plus build-up until next soil test

Index 4 Skip application for one year, then revert to maintenance

34)

Save Money in Index 4 - Dairy Example

Dairy – 2 cows / ha

Index 3 advice (grazing) = 14 kg/ha P & 30 kg/ha K

Cost of P and K = €58 /ha

Soil Test shows Index 4

Save €58 /ha/yr until drops to Index 3

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Save Money in Index 4 - Drystock Example

Drystock – 2 LU / ha

Index 3 advice (grazing) = 10 kg/ha P & 15 kg/ha K

Cost of P and K = €35 /ha

Soil Test shows Index 4

Save €35 /ha/yr until drops to Index 3

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Lost production in Index 1 & 2 - Dairy Same Example

Dairy – 2 cows / ha

Index 3 advice (grazing) = 14 kg/ha P & 30 kg/ha K

Production loss in Index 1 vs. Index 3 Approximately 1.5 t/ha/yr of grass DM

Worth €400 /ha/yr

Additional P and K for build up = 20 kg/ha P & 60 kg/haK Additional Cost = €100 ha/yr until soil P / K increases

Long-term investment – benefits of increasing to Index 3

Soil pH needs to beright as well !

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Lost production in Index 1 & 2 - Drystock Same Example

Drystock – 2 cows / ha

Index 3 advice (grazing) = 10 kg/ha P & 15 kg/ha K

Production loss in Index 1 vs. Index 3 Approximately 1.5 t/ha/yr of grass DM

Worth €400 /ha/yr

Additional P and K for build up = 20 kg/ha P & 60 kg/haK Additional Cost = €100 ha/yr until soil P / K increases

Long-term investment – benefits of increasing to Index 3

Soil pH needs to beright as well !

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Variation in Soil test results Not all the farm is the same – different fertilizers needed in different fields Often higher close to farmyard – slurry High P does not always mean high K

Fu et al 2010

Phosphorus Potassium

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Steps to Soil Fertility Management

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Soil Fertility Week(4-8 February 2013)

Slurry Value 1000 gallons = ??

50 kg

N P K

4 - 0.7 - 5

50 kg

N P K

6 - 5 - 30

50 kg

N P K

3 - 5 - 30

Soiled Water

All Year

Cattle Slurry (Splashplate)

Spring Summer

50 kg

N P K

19 - 7 - 20

Pig Slurry

Trailing Shoe

+ 3 units N/ 1000 gallons

In spring orsummer

50 kg

N P K

3 - 2.5 - 12

FYM (1 ton)

5 / 1000 gals 24 / 1000 gals 22 / 1000 gals

28 / 1000 gals 10 / ton

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Contribution to Slurry Value

Cattle Slurry

N

12%

P

19%

K

69%

Majority of the value is inP and K

Aim to get best use of bothP and K in slurry

Timing or method

No effect on P and K

Big effect on N

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Soil Fertility Week(4-8 February 2013)

Slurry Variability - Hydrometer

Beware of average values

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Soil Fertility Week(4-8 February 2013)

Decisions with slurry1. Where to spread

P & K requirements

Target fields with:

low soil P and K

High requirements (e.g.silage)

2. When to spread Maximise N availability

Weather as important asseason, but spring generallybest

Trailing shoe / bandspreaderwill also increase N value

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Steps to Soil Fertility Management

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Soil Fertility Week(4-8 February 2013)

Nutrient Balance – What is the Weakest Link ?

Nutrient in shortestsupply limitsdetermines yield Especially true with P

and K

Fertilizer Planning Soil tests & Cropping

Slurry & fertilizers Straight K

N-P products

N-K productsN P K

Fertilizer

N PFertilizer

KFertilizer

Buy what you need- Not what you’re being sold !!

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Sulphur >30% of Irish soils require S

for optimum yield

No soil test

Soil texture

Light texture (>50% sand)

Low organic matter (<3%org C)

On deficient soils:

Silage 20 kg/ha of S per cut

Grazing 20kg/ha per year

47)

Spreading fertilizer accuratelyApplication rate is affected by:

Forward speed

Regulator setting

Bout width

Fertiliser type and quality

Agitator action, flow rate

Spreader maintenance is veryimportant Replace vanes regularly

Consult spreader manual fordifferent products / settings

N P KFertilizer

It’s tooexpensive tobe spreadbadly !!

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Timing P and K applicationP

Autumn restricted by nitrates rules (15 Sept)

Index 3 - apply little and often through the year

Index 1 and 2 Apply some in spring

Remainder – apply little & often

K No nitrates timing restrictions (straight K)

Avoid > 90 kg/ha in spring Can reduce Mg in grass

K Fixing soils: No build up

Little and often

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Lime, Slurry and Urea interactions Lime and Slurry

P and K – no major issue

N Slurry before lime – no problem

Lime before slurry – avoid slurry for 3-6 months

Lime and Fertilizer N CAN – no problem

Urea Urea before lime – no problem

Lime before Urea – avoid urea for 3-6 months

Fertilizer N and slurry Delay fertilizer N for 4-7 days

CAN vs. Urea – No difference

High pH (Lime) increases ammonia (NH3) volatilisation

Slurry is a carbon source for denitrification allow 3 days for carbon to stabilise

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Fertilizer Planning A fertilizer Plan brings everything together

Field by field recommendations

Compliance with regulations

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Soil Fertility Management Targets Have soil analysis for whole farm

Soil pH between 6 and 6.5 in all fields

6.0 – 6.2 where high Mo (grassland)

P and K Index 3 in all fields

Index 4 is a resource Exploit it

Index 1 & 2 should be increased to Index 3

Optimise slurry first – then top up with fertilizer as required

Nutrient inputs in proper balance

Fertilizer planning is key to this

Thank you for yourattention

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