www.adas.co.uk

Cropping for reduced climate change: reducing emissions

from N fertiliser useDaniel Kindred, ADAS Boxworth

daniel.kindred@adas.co.uk

Farming Futures event 5 March 2010

Agenda

The problem – N fertiliser

Possible solutions

Revising N management

Low N varieties / species

Designing N efficient systems

Conclusions

Simple N cycle

Deposition

soil organic matter

Offtake

SoilMineral N

MineralisationImmobilisation

Volatilisation

Denitrification

Nfertiliser

organicmanures

LeachingSoil N Supply = N available for crop uptake through the season, but notcoming from N fertiliser or manure in that season

Fixation

GHG costs for crop products

1 tonne wheat grain

Seed + Agchems

Diesel use

Drying

non-N fertilisers

N fertiliser manufacture

Soil N2O -fert N

Soil N2O - residues

Seed/ Ag chems

Diesel use

Grain drying Non-N

fertilisers

N fertiliser manufacture

Soil N2O emissions

from N fertiliser use

Soil N2O emissions from crop residues

LARGE UNCERTAINTIES

Tonne of Wheat Grain

Loaf of white Bread

Packaging

Transport

Processing

Waste

other wheat costs

N fertilisermanufactureSoil N2O

raw materials

Loaf of white bread

Other raw materials

Packaging

TransportProcessing

Other wheat costs?

? ?

The problem – N fertiliser

Energy intensive manufactureN2O emissions from nitric acid production

N2O from soilsAssumed to be linearly related to N fertiliser applications

… plus emissions from incorporating crop residues

Need ‘smart’ emission factors to reflect ‘true’ emissions from UK arable crops & different crop systems

Current work seeking to develop these

Minimising nitrous oxide emissions from arable crops - MIN-NO

MINNO aims: To improve estimates of N2O emissions

For UK GHG inventoryFor GHG accounting

MINNO activitiesN response experiments with N2O measurements in main arable cropsModelling soil N2O emissionsLife cycle analysis for key arable products

SA LINK LK09128; HGCA project 3474

N Fertiliser rates to minimise GHGs?

How much N should we apply if we want to minimise GHG emissions?

0

200

400

600

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1000

1200

0 50 100 150 200 250 300 350 400

N fertliser applied (kg/ha)

GH

G e

mis

sion

s (k

g C

O2

e/t)

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Yie

ld (t

/ha)

Operations Agrochemicals

Grain yield

N effects on GHG emissions

Farm Diesel useAg Chems & non-N fert

Grain yield

Kindred et al. (2008) Aspects of Applied Biology 88

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200

400

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0 50 100 150 200 250 300 350 400

N fertliser applied (kg/ha)

GH

G e

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sion

s (k

g C

O2

e/t)

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Yie

ld (t

/ha)

N fertiliser emissions

Agrochemicals

Operations

Grain yield

N effects on GHG emissions

N fertiliser - manufacture

Grain yield

Farm Diesel useAg Chems & non-N fert

N fertiliser - manufacture

Kindred et al. (2008) Aspects of Applied Biology 88

0

200

400

600

800

1000

1200

0 50 100 150 200 250 300 350 400

N fertliser applied (kg/ha)

GH

G e

mis

sion

s (k

g C

O2

e/t)

0

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6

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12

Yie

ld (t

/ha)

Soil N20 emissions

N fertiliser emissions

Agrochemicals

Operations

Grain yield

Optimising N to minimise GHGs

Optima to minimise GHGs?

Grain yield

Farm Diesel useAg Chems & non-N fert

N fertiliser - manufacture

Soil N2O emissions

Kindred et al. (2008) Aspects of Applied Biology 88

But … N fertiliser Reduces land requirement

Deforestation

yield, t/ha

land required, ha/tonne

N applied, kg/ha0

…Reduces pressure on Land Use Change

Loss of habitats & biodiversityCarbon lost from soils and canopy

• 5900 Mt CO2eq per year • cf aviation of <3000 Mt per year

Grassland to crop – 5t CO2/haForest to crop – 29t CO2/ha

cf crop inputs GHG costs ~3t CO2e/ha

0

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400

600

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0 50 100 150 200 250 300 350 400

N fertliser applied (kg/ha)

GH

G e

mis

sion

s (k

g C

O2

e/t)

0

2

4

6

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Yie

ld (t

/ha)

Land use changeSoil N20 emissionsN fertiliser emissionsAgrochemicalsOperationsGrain yield

Reducing N rates below economic optima may not give GHG reductions globally

Large uncertainties in ILUC calculations, depending on assumptions

– optima can be >300kg/ha

Kindred et al. (2008) Aspects of Applied Biology 88

Grain yield

Farm Diesel useAg Chems & non-N fert

N fertiliser - manufacture

Soil N2O emissionsIndirect emissions via LUC

Need to achieve economically optimal N rates

Plan your N useAccount for N in soils and manure applicationsAvoid applying more than the optima

It isn’t economic!

Monitor success of N managementGrain N% is key measure www.planet4farmers.co.uk

www.nutrientmanagement.orgwww.hgca.com

Optimising economic N applications- Errors in N use are inevitable

Error in N Predictiondifference from optimum N, kg/ha

Data from HGCA Project 3084: modern varieties, 2005-7

Net loss from

optimum profit target

zone

little economic loss

Best predictions from The Fertiliser Manual

using SMN

Important to ensure

accuracy on average

and avoid big mistakes

-£125

-£100

-£75

-£50

-£25

£0-200 -100 0 100 200

Calculating Fertiliser N requirement

Crop N DemandCrop N DemandCrop N Demand

LeachingLeaching

MineralisationImmobilisation

Soil N SupplySoil N SupplySoil N Supply

Grain yieldGrain protein%

Crop N Crop N RequirementRequirement

Fertiliser & Manure N

Account for N in soil – Soil N SupplyVariable with previous cropping, soil, & rainfallSMN sampling worthwhile where SNS large or uncertain

Manure historyGrass historyHigh soil organic matter

Also barometer fields as a check?HGCA Project 3084 – SNS Best Practice

Autumn sampling 0-60cm OKExcept shallow soils

or Spring sampling 0-90Get samples to lab quickly

Account for N in manures

Use MANNER or look-up tablesGives readily available N to the crop

Also calculates emissions

www.adas.co.uk/MANNER

www.planet4farmers.co.uk

Monitor Success

GrainYield(t/ha)

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-300 -200 -100 0 100 200 300

N supply (kg/ha)

7

8

9

10

11

12

13optimum N supply

(N:grain prices, 5:1)

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-300 -200 -100 0 100 200 300

N supply (kg/ha)

7

8

9

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11

12

13

Margin (t/ha equiv.)

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-300 -200 -100 0 100 200 300

N supply (kg/ha)

7

8

9

10

11

12

13

GrainProtein

(%)

from soil

Monitor & Review … vital for good management

N errors are inevitableThey are usually unseenSmall errors seldom matterBeware of big errorsErrors can accumulate

if not correctedexcept light or shallow soils

Checklist providedKey check is grain protein

ActionDouble-check any odd fieldsAdjust strategy gradually.

Improving N management by precision farming

New ‘Auto-N’ project

Effects of improved N management on GHG emissions

Improve accuracy of N decisionsLess lost yield from sub-optimal applicationsLess wasted fertiliser from super-optimal applications

But, fertiliser adjustments may be upward as well as downwardNot necessarily big GHG cuts?

Many farmers already doing best practice?

Need to impact those who are not

0.0

0.5

1.0

1.5

2.0

Late autumn/winter (IPCC1996)

Late autumn/winter (IPCC2006)

Spring

Tota

l N a

pplie

d lo

st a

s N

2O (%

)

Indirect soil emission - ammoniaIndirect soil emission - nitrateDirect soil emission

Timing N applications to reduce N2O emissions?

2

1

0

N2O

em

issi

ons

%N

app

lied

Aut

umn

App

licat

ion

Spr

ing

App

licat

ion

Cattle slurry, mean of 5 experiments on

grasslandApply slurry & manures in spring if possible

Avoid N fertiliser applications to warm & wet soils?

Apply little & often, more closely match crop demand ???

More evidence needed before making changes to fertiliser N timing

Choose N products to reduce GHGs?

Manufacturing GHG emissions lower in urea than ammonium nitrate

~3 vs ~7kg CO2e /kg N (but uncertain??)Due to N2O from Nitric acid manufacture

Abatement technologies in many EU plantsGHG costs of AN may be close to urea

BUT, greater ammonia emissions from ureaGives indirect N2O emissionsHigher N rates required for urea?

Little evidence for difference in soil N2O emissions between urea & AN in England

Nitrification inhibitors may reduce N2O emissionsYet to be proven for UK conditions in practice

New Defra project starting ADAS/ North Wyke Research

Use varieties with reduced N requirements?

LINK Projects finding varieties in wheat & OSR which may need less N fertiliser

Low protein grainCheaper to growYields maintained

Reduced pollution & GHGsNeed N testing regimes in NL/RL to get such varieties to market

GREEN grain

HGCA Project 2979SA LINK LK0959

ElsomsSeeds

GREEN oil

SA LINK LK0979

Triticale – high yields, low N requirement?

Look-see experiment in 2009 showed remarkable potential of triticale

Markets for animal feed & bioethanol

HGCA project 3617 testing wheat/triticale in 2010

Could replace much of the 2nd wheat area?

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0 50 100 150 200 250

N applied (kg N/ha)

grai

n yi

eld

(t/ha

)

TriticaleOatsBarleyWheat

2nd wheat site, clay loam, Suffolk 2009

Consider low-N systemsRotations

Use of legumesBut N2O emissions still occur

Fallows, leys?Reduced productivity & profitability?

spring cropping?Reduced N applications

But reduced yields?Cover crops?

Intercrop with pulses or clover?

STAR project

Low-N Bread?

Conclusions – to mitigate GHGs from N fertiliser use:

DO:Ensure Best Practice for nitrogen use

Account for N in manuresUse manure N efficiently

Account for N in soilsMonitor success – use grain N%

DON’T (because evidence is so far insufficient):Reduce N rates below economic optimaAlter planned N fertiliser timings

(Do avoid applying to warm wet soils if possible)Switch from AN to urea

LOOK OUT FOR & CONSIDER:Growing N efficient varieties & species

Triticale?using N efficient cropping systemsPrecision Farming techniquesNitrification inhibitors & N2O abated fertiliser

Past Spatial Information(Soil AWC, OM, P & K, etc)

Past cropsYieldsGrain N%

Previous cropYield & N%N uptakeFert N applied

1.Judge N Demand

Expected yieldx 23 kg/t N

2.Judge N Supply

N balances fromprevious crop type &

sensing data

4. Schedule & Adjust

N applicationsManage canopy

5.Monitor Success

N use, Yield, Grain N%, Lodging.

3.Calculate Fert.N Requirement

(Demand – supply)Fertiliser recovery

Fertiliser recoveryFertiliser type

Field Information Soil type (texture & chalk)Weather

Previous cropVarietySowing date

Harvest mapping

Calculation & interpretation

Grain YieldGrain N%N offtakesN optima

N Management Cycle

Canopy SensingA. Over winter Monitor crop size &

thermal time N-unlimited growthTime of N limitationAdjust predicted SNS

B. 1st N ApplicationMonitor crop size,

tillering & thermal time

Use predicted SNS & benchmark GAI to set 1st N applicat’n

C. Main N Applicn.Monitor crop size &

greennessUse benchmark GAI

to set 2nd N applic’n

D. Final N Applicn.Monitor crop size &

greennessCalc N uptake &

remaining avail NRe-evaluate

realisable yield & N demand

Set 3rd N application.