Mineral fertilizer, climate effects and options for improvement LMDs konferanse om klima og landbruk, Oslo, 03 June 2009 Frank Brentrup, Yara Int., Research Centre Hanninghof
Crops need mineral nutrients to grow Crops absorb mineral nutrients and water from the soil Mineral nutrients are essential building blocks for crops Date: 2003-11-18 - Page: 2
Mineral fertilizers replace the nutrients that are exported with the harvest Supply of crop residues and organic fertilizer NPK Export of nutrients with the harvest Organic substance, humus Mineralisation N S P K Mg Soil The soil is depleted without mineral fertilizers Date: 2003-11-18 - Page: 3
Mineral fertilizers are needed Billion people 8 6 4 48% People nourished by use of mineral fertilizers 2 without mineral fertilizers 0 Today Source: adopted from Erisman et al. (2008), Nature Geoscience without fertilizer with fertilizer Today, nearly 50% of the world s population is nourished from the use of mineral fertilizers Date: 2003-11-18 - Page: 4
More people Less arable land Arable area (in ha per person) 0.3 0.28 0.26 0.24 0.22 World population (in Bn) 8.5 8 7.5 7 6.5 6 0.2 1998 2030 5.5 We must produce more food per hectar Date: 2003-11-18 - Page: 5
Environmental effects of N fertilizer use Benefits Increased biomass production Food, Feed, Energy Potential for land preservation Efficient land use Carbon fixation Impacts Eutrophication Nitrate leaching Ammonia volatilisation Off-site acidification Ammonia volatilisaton Global warming CO2 emissions N2O emissions Date: 2003-11-18 - Page: 6
Climate gas emissions GLOBAL = 49 bn t CO2eq (agriculture contributes 26%) Energy, Waste, Industry, etc. (74%) Production of mineral N fertilizer (0.8%)* N2O from mineral N fertilizer use (1.3%)* N2O from organic N sources (3.8%) Other agricultural GHGs, mainly CH4 (8.4%) Land use change for agriculture (12%) Based on IPCC (2007), Bellarby et al. (2008), *EFMA calculation Date: 2003-11-18 - Page: 7
Climate gas emissions GLOBAL = 49 bn t CO2eq (agriculture contributes 26%) EU-27 = 5 bn t CO2eq (agriculture contributes 9%) Energy, Waste, Industry, etc. (74%) Production of mineral N fertilizer (0.8%)* N2O from mineral N fertilizer use (1.3%)* N2O from organic N sources (3.8%) Other agricultural GHGs, mainly CH4 (8.4%) 90% 1.1%* 1.1%* 3,2% 4.6% Land use change for agriculture (12%) Based on IPCC (2007), Bellarby et al. (2008), *EFMA calculation Based on UNFCCC (2008), * EFMA calculation Emission from land use change is large, but not in Europe Less intensified agriculture in Europe more deforestation more emission Date: 2003-11-18 - Page: 8
Sources of agricultural GHG emissions (EU-27, 2005) Agriculture contributes 9% to the total GHG emission of 5014 mio. t CO 2 eq Other agricultural GHGs, mainly CH 4 from cattle and manure (52%) N 2 O from mineral N fertilizer use (13%)* N 2 O from organic N sources (35%) Source: United Nations Framework Convention on Climate Change (UNFCCC;2008) * EFMA calculation Date: 2003-11-18 - Page: 9
Sources of N 2 O from agriculture N 2 O emission EU27: 240 mio t CO 2 eq 33% Emission after volatilization & leaching Mineral fertilizer N 25% 3% 8% 5% 14% 12% Biological Nitrogen Fixation Crop residues Organic soils Manure application & grazing animals Source: United Nations Framework Convention on Climate Change (UNFCCC;2008) Date: 2003-11-18 - Page: 10
A life-cycle perspective on fertilizer N 2 CO 2, N 2 O, CO 2, NOx, NH 3, NO 3, N 2 O, N 2 Biomass Production Logistic Application Uptake Natural gas (feedstock) Fuel Minerals Fuel Fuel Sunlight CO 2 Land Date: 2003-11-18 - Page: 11
Different fertilizers have different impacts Fertilizer production Application to soil Life-cycle perspective: Production & application kg CO2eq/kg N 12 10 8 6 4 2 0 Urea CAN * 12 10 8 6 4 2 0 Urea CAN * 12 10 8 6 4 2 0 Urea CAN * * CAN production includes N2O abatement catalyst A life-cycle perspective on fertilizers is important (otherwise regulators may wrongly favour urea) Date: 2003-11-18 - Page: 12
High intensity in crop production - Problem or solution?
Yield response to nitrogen application in a long-term field trial with winter wheat Grain yield (t/ha) 10 8 100% intensity 6 50% intensity 4 economic opt.n rate 2 0 0% intensity 0 50 100 150 200 250 300 N application rate (kg N/ha) Long term trial: Rothamsted, UK Date: 2003-11-18 - Page: 14
100% intensity 0% intensity Date: 2003-11-18 - Page: 15
The carbon footprint of wheat production increases with the N application rate Global warming: kg CO2 eq. / ha 3000 2500 2000 1500 1000 500 0 without N 50% of optimum economic optimum N rate Date: 2003-11-18 - Page: 16
On the other hand the positive GHG balance ex-field is enhanced by fertilizer use Global warming: kg CO2 eq. / ha 35000 30000 25000 20000 15000 GHG fixed in biomass (grain + straw) 10000 5000 0 without N 50% of optimum economic optimum N rate GHG emissions Date: 2003-11-18 - Page: 17
If the harvested crop is used as food or feed, the CO2 fixation is only short-term Global warming: kg CO2 eq. / ha 35000 30000 25000 20000 15000 GHG fixed in biomass (grain + straw) 10000 5000 0 without N 50% of optimum economic optimum N rate GHG emissions The CO2 fixation can be regarded as a real CO2 saving, only if the harvested biomass is used as bio-fuel and, thus, replaces fossil fuels. Date: 2003-11-18 - Page: 18
To achieve the same yield, reduced production intensity needs more land and increases GHG emissions Global warming: kg CO2 eq. / ha 12000 10000 8000 CO 2 release due to additional land use needed to compensate for lower yields 6000 4000 2000 0 without N 50% of optimum economic optimum N rate Date: 2003-11-18 - Page: 19
Options to improve the carbon footprint of fertilizers in crop production
kg CO 2 -equivalents / ha Contribution of the single GHG emissions to the total carbon footprint per ha Based on a long-term field trial with winter wheat (UK), N source = Ammoniumnitrate 3000 Hot-spots 2500 2000 1500 1000 500 N2O N2O N2O_field CO2_field CO2_trans N2O_prod CO2_prod 0 economic optimum N rate Date: 2003-11-18 - Page: 21
Improvements in nitric acid production Nitric acid plant Nitrous oxide (N2O) abatement catalyst Date: 2003-11-18 - Page: 22
Carbon footprint (kg CO 2-eq. / ha) Impact of the de-n2o catalyst on the carbon footprint of crop production Based on a long-term field trial with winter wheat (UK), N source = Ammoniumnitrate 3000 2500 without de-n2o catalyst with de-n2o catalyst 2000 1500 1000 N2O_field CO2_field CO2_trans N2O_prod CO2_prod 500 0 Wheat produced at economic optimum N rate Date: 2003-11-18 - Page: 23
Two natural soil processes release N 2 O Nitrification N 2 O Urea/Ammonium Nitrate Soil organisms use ammonium (NH 4 ) as energy source Denitrification N 2 O N 2 O from both processes 1% of N (IPCC, 2006) Nitrate N 2 gas Conditional: if oxygen (O 2 ) is depleted (water logging), soil organisms use oxygen from nitrate (NO 3 ) for respiration Date: 2003-11-18 - Page: 24
kg CO 2 -equivalents / ha Impact of soil and climate on the carbon footprint of crop production 6000 4.67% of total N input as N2O_field * 5000 4000 3000 2000 0.84% 1.28% 2.05% N2O_field CO2_field CO2_trans N2O_prod CO2_prod 1000 0 Drainage: Texture: Climate: good loam temp poor loam temp poor clay temp poor clay trop Other important factors: - Soil organic carbon - Soil ph - Fertilizer type Date: 2003-11-18 - Page: 25 * Calculated according to Bouwman model (Bouwman et al., 2002), uncertainty range 40% to +70%
N2O-N emission (% of applied N) Average N 2 O emissions are lower from Nitrates than from urea and ammonium fertilizers Up to now, N 2 O emissions from N fertilizers are estimated independently from the N form (default IPCC factor, red bar in the graph below). But a new analysis of about 900 in-field measurements from 139 experiments shows differences in N 2 O emissions from different N fertilizers. 1,2 1 0,8 0,6 0,4 0,2 0 default IPCC factor Urea UAN AS AN CAN Date: 2003-11-18 - Page: 26 Source: Bouwman et al. (2002)
Options to reduce in-field N2O emission Any means that improve nitrogen use efficiency, in particular Adjust N application rate to actual crop N demand ( soil and plant analysis) Synchronize N application with crop N uptake ( split application, just-in-time fertilization) Apply nitrate-based N sources on well aerated and non-waterlogged soils Maintain a good soil structure (no compaction, good drainage) Date: 2003-11-18 - Page: 28
Yara develops tools to support Good Agricultural Practices and to increase N use efficiency Software and crop monitoring tools help to calculate the right nutrient rate => these tools helped to improve nutrient use efficiency Date: 2003-11-18 - Page: 29
The nitrogen use efficiency in Europe is increasing NUE in % (moving average 3 years) 70 60 50 40 30 20 N use efficiency (NUE in %) = (N removal/n application) x 100 1987 1989 1991 1993 1995 1997 1999 2001 2003 2005 Source: own calculation based on FAO and Efma data Date: 2003-11-18 - Page: 30
The N 2 O emissions from soil are decreasing N 2 O emissions from agricultural soils in Europe (mio t CO 2 eq) 320 300 280 260 240 220 200 1990 1992 1994 1996 1998 2000 2002 2004 2006 Year Source: United Nations Framework Convention on Climate Change (UNFCCC, 2008) Date: 2003-11-18 - Page: 31
The N use efficiency in Europe will further improve Average EU27 2006/07 Average of 139 field trials** Grain yield t per ha - fresh matter* 4.9 9.3 N-content in grain dry matter (%) 2.00 2.09 N removal in grain (kg N/ha) 82 167 N fertilizer application (kg N/ha) N deposition (kg N/ha) 111 20 181 20 N use efficiency (N removal/ N input) * 100 62 % 83 % Source: * FAO, ** Yara field trials Date: 2003-11-18 - Page: 32
The Key Facts Fertilizers are needed for feeding the world Agricultural land must be used in the most efficient way, to protect wildlife and minimize climate change Fertilizers, used correctly, will contribute to solving climate change Europe has today the most efficient production plants and the most modern agriculture N 2 O is released by natural processes regardless of the origin of the nitrogen in the soil To reduce N 2 O the field the nitrogen use efficiency shall be improved by good agricultural practices Date: 2003-11-18 - Page: 33