managing soil fertility - teagasc · 2019-06-25 · 3 soil fertility data teagasc analyse c. 35,000...
TRANSCRIPT
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
NF
ert
iliz
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us
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00
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)
0
20
40
60
80
100
120
140
P&
KF
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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
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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%
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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
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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
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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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