Cropping for Reduced Climate Change: reducing emissions from nitrogen fertiliser - Daniel Kindred (ADAS)
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This presentation formed part of the Farming Futures workshop 'Cropping Climate Change: Making business sense of nitrous oxide and the nitorgen cycle' March 5th 2010
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Cropping for Reduced Climate Change: reducing emissions from nitrogen fertiliser - Daniel Kindred (ADAS)
- 1. Cropping for reduced climate change: reducing emissions from N fertiliser use Daniel Kindred, ADAS Boxworth daniel.kindred@adas.co.uk Farming Futures event 5 March 2010 www.adas.co.uk
- 2. Agenda The problem – N fertiliser Possible solutions Revising N management Low N varieties / species Designing N efficient systems Conclusions
- 3. Simple N cycle Offtake Deposition Volatilisation N organic fertiliser manures soil organic matter Fixation Mineralisation Immobilisation Denitrification Soil Mineral N Soil N Supply = N available for crop Leaching uptake through the season, but not coming from N fertiliser or manure in that season
- 4. GHG costs for crop products Tonne of Wheat Grain Loaf of white bread Transport Grain Loaf of white Bread Processing drying Non-N Packaging Diesel 1 tonne wheat grain fertilisers Packaging use Other raw Seed/ materials Transport Ag chems Seed + Agchems Processing Diesel use Waste ? Drying non-N fertilisers ? other wheat costs Other wheat ? N fertiliser manufacture costs N fertiliser manufacture Soil N2O -fert N Soil N2O Soil N2O - residues raw materials Soil N2O emissions Soil N2O from crop emissions N fertiliser residues from N manufacture fertiliser use LARGE UNCERTAINTIES
- 5. The problem – N fertiliser Energy intensive manufacture N2O emissions from nitric acid production N2O from soils Assumed 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
- 6. Minimising nitrous oxide emissions from arable crops - MIN-NO MINNO aims: To improve estimates of N2O emissions For UK GHG inventory For GHG accounting MINNO activities N response experiments with N2O measurements in main arable crops Modelling soil N2O emissions Life cycle analysis for key arable products SA LINK LK09128; HGCA project 3474
- 7. N Fertiliser rates to minimise GHGs? How much N should we apply if we want to minimise GHG emissions?
- 8. N effects on GHG emissions 1200 12 Grain yield GHG emissions (kg CO2 e/t) 1000 10 Operations Agrochemicals 800 8 Yield (t/ha) Grain yield Ag Chems & non-N fert 600 Farm Diesel use 6 400 4 200 2 0 0 0 50 100 150 200 250 300 350 400 N fertliser applied (kg/ha) Kindred et al. (2008) Aspects of Applied Biology 88
- 9. N effects on GHG emissions 1200 12 Grain yield GHG emissions (kg CO2 e/t) 1000 10 N fertiliser emissions 800 Agrochemicals 8 N fertiliser - manufacture Yield (t/ha) Operations N fertiliser - manufacture Ag Chems & non-N fert 600 Grain yield 6 Farm Diesel use 400 4 200 2 0 0 0 50 100 150 200 250 300 350 400 N fertliser applied (kg/ha) Kindred et al. (2008) Aspects of Applied Biology 88
- 10. Optimising N to minimise GHGs 1200 12 Grain yield GHG emissions (kg CO2 e/t) 1000 10 Soil N20 emissions Soil N O emissions 2 800 N fertiliser emissions 8 N fertiliser - manufacture Agrochemicals Yield (t/ha) Operations Ag Chems & non-N fert 600 Grain yield 6 Farm Diesel use 400 4 Optima to minimise GHGs? 200 2 0 0 0 50 100 150 200 250 300 350 400 N fertliser applied (kg/ha) Kindred et al. (2008) Aspects of Applied Biology 88
- 11. But … N fertiliser Reduces land requirement yield, t/ha land required, ha/tonne Deforestation 0 N applied, kg/ha
- 12. …Reduces pressure on Land Use Change Loss of habitats & biodiversity Carbon lost from soils and canopy • 5900 Mt CO2eq per year • cf aviation of <3000 Mt per year Grassland to crop – 5t CO2/ha Forest to crop – 29t CO2/ha cf crop inputs GHG costs ~3t CO2e/ha
- 13. Reducing N rates below economic optima may not give GHG reductions globally 1200 12 Grain yield GHG emissions (kg CO2 e/t) 1000 10 Indirect emissions via LUC Land use change Soil N2O emissions Soil N20 emissions 800 8 N fertiliser emissions N fertiliser - manufacture Yield (t/ha) Agrochemicals Operations Ag Chems & non-N fert 600 Grain yield 6 Farm Diesel use 400 4 Large uncertainties in ILUC 200 calculations, depending on assumptions 2 – optima can be >300kg/ha 0 0 0 50 100 150 200 250 300 350 400 N fertliser applied (kg/ha) Kindred et al. (2008) Aspects of Applied Biology 88
- 14. Need to achieve economically optimal N rates Plan your N use Account for N in soils and manure applications Avoid applying more than the optima It isn’t economic! Monitor success of N management Grain N% is key measure www.planet4farmers.co.uk www.nutrientmanagement.org www.hgca.com
- 15. Optimising economic N applications - Errors in N use are inevitable Best predictions from Error in N Prediction The Fertiliser Manual using SMN difference from optimum N, kg/ha -200 -100 0 100 200 £0 -£25 Net loss from -£50 Important to optimum ensure profit -£75 target accuracy on zone average -£100 and avoid big mistakes -£125 little economic Data from HGCA Project 3084: modern varieties, 2005-7 loss
- 16. Calculating Fertiliser N requirement Grain yield Grain protein% Crop N Demand Crop N Requirement Fertiliser & Manure N Soil N Supply Immobilisation Mineralisation Leaching
- 17. Account for N in soil – Soil N Supply Variable with previous cropping, soil, & rainfall SMN sampling worthwhile where SNS large or uncertain Manure history Grass history High soil organic matter Also barometer fields as a check? HGCA Project 3084 – SNS Best Practice Autumn sampling 0-60cm OK Except shallow soils or Spring sampling 0-90 Get samples to lab quickly
- 18. Account for N in manures Use MANNER or look-up tables Gives readily available N to the crop Also calculates emissions www.adas.co.uk/MANNER www.planet4farmers.co.uk
- 19. Monitor Success optimum N supply 12 (N:grain prices, 5:1) 13 from 10 soil 12 Grain 8 11 Grain Margin (t/ha equiv.) Yield Protein (t/ha) 6 10 (%) 4 9 2 8 0 7 -300 -200 -100 0 100 100 200 300 N supply (kg/ha)
- 20. Monitor & Review … vital for good management N errors are inevitable They are usually unseen Small errors seldom matter Beware of big errors Errors can accumulate if not corrected except light or shallow soils Checklist provided Key check is grain protein Action Double-check any odd fields Adjust strategy gradually.
- 21. Improving N management by precision farming New ‘Auto-N’ project
- 22. Effects of improved N management on GHG emissions Improve accuracy of N decisions Less lost yield from sub-optimal applications Less wasted fertiliser from super- optimal applications But, fertiliser adjustments may be upward as well as downward Not necessarily big GHG cuts? Many farmers already doing best practice? Need to impact those who are not
- 23. Timing N applications to reduce N2O emissions? Cattle slurry, mean of N2O emissions %N applied 5 experiments on 2.0 Indirectgrassland- amm onia soil em ission Apply slurry & manures in spring if Indirect soil em ission - nitrate 2 Total N applied lost as N 2O (%) Direct soil emission 1.5 possible 1.0 Avoid N fertiliser applications to 1 0.5 warm & wet soils? Apply little & often, more closely 0.0 Late autumn/w inter (IPCC 0 Late autumn/winter (IPCC Spring Application Autumn Application Spring 1996) 2006) match crop demand ??? More evidence needed before making changes to fertiliser N timing
- 24. 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 plants GHG costs of AN may be close to urea BUT, greater ammonia emissions from urea Gives indirect N2O emissions Higher N rates required for urea? Little evidence for difference in soil N2O emissions between urea & AN in England Nitrification inhibitors may reduce N2O emissions Yet to be proven for UK conditions in practice New Defra project starting ADAS/ North Wyke Research
- 25. Use varieties with reduced N requirements? LINK Projects finding varieties in wheat & OSR which may need less N fertiliser Low protein grain GREEN oil Cheaper to grow GREEN grain Yields maintained Elsoms Seeds HGCA Project 2979 SA LINK LK0959 SA LINK LK0979 Reduced pollution & GHGs Need N testing regimes in NL/RL to get such varieties to market
- 26. Triticale – high yields, low N requirement? Look-see experiment in 2009 showed remarkable 12 Triticale potential of triticale 10 Oats Markets for animal feed & grain yield (t/ha) Barley 8 Wheat bioethanol 6 HGCA project 3617 4 testing wheat/triticale in 2 2010 0 Could replace much of 0 50 100 150 200 250 the 2nd wheat area? N applied (kg N/ha) 2nd wheat site, clay loam, Suffolk 2009
- 27. Consider low-N systems Rotations Use of legumes But 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?
- 28. Conclusions – to mitigate GHGs from N fertiliser use: DO: Ensure Best Practice for nitrogen use Account for N in manures Use manure N efficiently Account for N in soils Monitor success – use grain N% DON’T (because evidence is so far insufficient): Reduce N rates below economic optima Alter 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 systems Precision Farming techniques Nitrification inhibitors & N2O abated fertiliser
- 29. Past Spatial Information Harvest mapping Canopy Sensing (Soil AWC, OM, P & K, etc) Grain Yield A. Over winter Grain N% Monitor crop size & Previous crop Past crops N offtakes thermal time Yield & N% Yields N optima N-unlimited growth N uptake Grain N% Time of N limitation Fert N applied Calculation & interpretation Adjust predicted SNS B. 1st N Application 5. Monitor crop size, 1. tillering & thermal Monitor Success Judge N Demand N use, Yield, time Expected yield Use predicted SNS & x 23 kg/t N Grain N%, Lodging. benchmark GAI to set 1st N applicat’n C. Main N Applicn. 2. N Management Cycle Monitor crop size & 4. greenness Judge N Supply N balances from Schedule & Adjust Use benchmark GAI previous crop type & N applications to set 2nd N applic’n sensing data Manage canopy 3. D. Final N Applicn. Calculate Fert. Monitor crop size & N Requirement greenness (Demand – supply) Calc N uptake & Fertiliser recovery remaining avail N Field Information Re-evaluate Soil type realisable yield & Previous crop (texture & N demand Variety chalk) Fertiliser recovery Set 3rd N application. Sowing date Weather Fertiliser type