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Transcript of David Norse — Increasing food security and minimising greenhouse gas emissions through improved...
Increasing food security and minimising greenhouse gas emissions through improved
nitrogen management – lessons from the Chinese experience
David Norse
International Conference on Climate Change and Food Security, Beijing, November 6-8, 2011
Agriculture is part of the problem and part of the solution
Agricultural drivers for climate change are a threat to current food security as well as to long
term food security
Outline
• N fertilizer and the trade-off between food security and climate change
• Overuse and misuse of N as a threat to current food security
• Minimising greenhouse gas (GHG) emissions through improved nitrogen management (INM) and other policy measures
• Implications of the Chinese experience for other developing countries
N use in China & food security
N fertilizer
Grain yield
N production and use as drivers for climate change
• Agriculture is the main source of the powerful GHGs CH4 and N2O driving climate change globally & China
• Synthetic N fertilizer production & use and manure are the main source of N2O & livestock are now the main source of CH4
• Food demand exceeds the amount that can be produced from organic N inputs
Agricultures contribution to global GHG emissions
Global mean:
70% of agricultural GHG
emissions are connected
with N fertilizer use: CO2 & N2O
Source: IPPC 4th Report
GHGs emissions from China’s agriculture
Source: SAIN, 2011
Source CO2 Methane Nitrous
oxide
Total
N fertilizer production & transport
(43 Mt)
235 26 13 274
P&K fertilizer production & transport 18 18N fertilizer use for crops (32 Mt) 57 (170 rice*) 176* 233(403)Other agricultural uses (3-5Mt) 15-25 15-25 30-50Livestock – enteric & manure 295-443 172-258 467-701Direct fossil energy inputs to agriculture 190 190Total agricultural emissions 515-25 491-639 376-472 1382-1636
Total economy emissions 6,000 7,230
Agricultural emissions as % of total national emissions
* not closely N related *provisional estimate for indirect N2O
19-22
Food demand, organic N inputs& unavoidable trade-offs
• Currently about 30 % of China’s N input comes from manure
• In the longer-term about 30% of synthetic N use could be replaced by N in manure & compost and biological N fixation but they also release GHGs
• Consequently food security will continue to be dependent on anthropogenic N inputs with some trade-offs between food security & climate change
Complexity of trade-offs betweenfood security and climate change
Much of the complexity stems from the way that overuse and misuse of N increases:
(a)GHG emissions & drives climate change, but
(b)Also causes or intensifies a range of other negative environmental impacts that increasingly threaten current food security
Current direct and indirect threats to food supply related to N use
• Yield loss• Restricted root growth• Soil acidification• Negative impacts on soil biology• Higher losses from pests & diseases• Increased lodging and greater harvesting losses• Greater eutrophication and increased frequency
and area of algal blooms
N overuse by province and crop
Province Crop Farmers rate
kg.N/ha
Recommended Rate* kg.N/ha
% overuse
% yield loss from overuse
Jiangsu rice 300 200 50 3
6 provinces rice 195 133 47 >5
N China plain wheat 325 128 150 4
N China plain maize 263 158 66 5
Shaanxi wheat 287 150‐225 >30 0
Shaanxi maize 249 125 100 8
Shandong tomato Up to 630 150-300 >80 10
Overuse of N and poor root growth
SAIN Policy Brief No 2
N Overuse Optimum N
Increase in top soil acidification:1980s -2000s
• Soil pH declined significantly in all major crop production areas & is projected to get worse
• It was caused primarily by high inputs of N fertilizer
• Acid deposition had only a small impact• Reduced productivity – toxic metals• Control is difficult and labour intensive
Source: Guo et al., 2010
Soil acidification greater with vegetables and fruit than cereals
Source: Guo et al., 2010
Soil group/region
1980s 2000s 2000s
All crop systems Cereals Vegetables & fruit
pH value pH value pH value
Red & yellow soils of South China
5.73 5.14 5.07
Paddy soils 6.33 6.20 5.98
North East 6.32 6.00 5.60
N China Plain & Loess Plateau
7.96 7.69 7.38
N related increase in eutrophicationand harmful algal blooms/red tides
1970s 1990s 2000 Mid 2000s 2008
Lake eutrophication %*
5 51 55-61
Red tides/year** 5 45 68
* 25-50% from crop N
** up to 60% estuarine N from crop production
Overuse of N and > crop diseases:Rice sheath blight
Source: Cu et al., 1996
Overuse and misuse of N as a threat to current food demand
Excess costs of production from overuse cause:•Reduced net farm income•Lower productivity growth & higher food price inflation which can limit the ability of the poor to buy all of their food needs
Costs of N overuse Province Crop Farmers
rate kg.N/ha
Recommended Rate* kg.N/ha
% overuse Cost of overuse RMB/ha
Jiangsu rice 300 200 50 400
6 provinces rice 195 133 47 250
N China plain wheat 325 128 150 800
N China plain maize 263 158 66 420
Shaanxi wheat 287 150‐225 >30 250-550
Shaanxi maize 249 125 100 500
Shandong tomato Up to 630 150-300 >80 1320-1920
Impact of overuse & misuse of N on farm incomes in Shaanxi
Source: Lu Yuelai, 2010
Income level(收入水平)
Total household income (yuan)
家庭总收入(元)
Cost of N overuse (yuan)
% of household income (占家庭收入百分比)
1st Q 1664 153 9
2nd Q 6489 249 4
3rd Q 10442 225 2
4th Q 20260 221 1
Average 平均 9728 212 2
Agriculture as part of the solution: most of the cost-effective measures to minimise agricultural GHGs emissions involve improved N management in crop and livestock production
Minimising agricultural GHGs
• Integrated nutrition management• Increased water use efficiency• Increased soil carbon• Improved livestock waste management • Feed productivity• Subsidies, PES, & environmental taxes• Monitoring & evaluation
What is improved nitrogen management (INM)
• Use of application rates of synthetic N fertilizers that allow for the N already in the soil, in manure and in irrigation water & do not exceed the amount needed for optimum crop yields.
• Ensuring that N fertilizers are applied at the right time & best place.
• Choosing the correct mix of N, P & K and the best type of fertilizer to minimize GHG & ammonia emissions
INM is not just about limitingN overuse
It is also correcting:•Lack of micronutrients which can limit N availability•Bad water management e.g. excessive irrigation which leaches nitrate below root zone•Tillage & residue management practices that reduce carbon sequestration
All of these can increase direct & indirect N2O emissions – complex trade-offs
INM and potential GHG savings in Beijing/Hebei/Shandong
Derived from Ju el., 2006
Farmers N rate
INM rate N saving from INM
% GHG reduction from INM
N input & GHG benefitkg synthetic N fertilizer/ha/yr
588 286 302 51
Other benefits:
Reduced N loss by leaching
56 23 33
Reduced N loss as ammonia
135 46 89
Livestock waste management– mix of policy instruments
• Planning controls on location• Building regulations regarding drainage &
waste storage requirements• Limits on stocking rates & manure or slurry
disposal• Support for anaerobic digestion and
organic fertiliser production
Water use efficiency
Mix of regulatory and economic incentives:• controls on abstraction; • full economic cost water pricing; • subsidies or grants for installing drip-
irrigation & fertigation
Implications of the Chinese experience for other developing
countries
• Importance of limiting overuse of N• Improving INM• Importance of good communications
between farmers, extension workers, scientists & engineers
• Sharing technological progress• Importance of appropriate funding for
agricultural development
Limiting overuse of N
Underuse rather than overuse is the main problem in most developing countries but:•Overuse is common in parts of India where there is cereal intensive production•Hot spots occur elsewhere in Asia, Africa and Latin America eg. peri-urban intensive vegetable production•Hence China’s experience with INM is helpful
Adopting and adapting INM
• IRRI has promoted the sharing of INM experience among rice producing countries but there is scope for extending this to other cropping systems
• Chinese experience with estimating N budgets, GHG emissions & other environmental impacts can provide other countries with methods and default values to formulate their approach to INM
Sharing technological progress
• Chinese progress in the development of cost-effective slow-release formulations of N fertilisers and nitrification inhibitors
• Development of small scale machinery for tillage and fertiliser placement
• Global public goods - hybrid varieties and advances in biotechnology
Conclusions
• N essential for food production but it creates substantial GHGs and other negative environmental impacts that threaten food security
• These trade-offs are current as well as long-term and can be reduced but not eliminated
• INM is a cost-effective win-win-win approach to reducing both current and climate change related threats to food security but wider policy measures are needed
• Underuse of N is the problem in most developing countries but there are N hotspots needing INM
Thanks to Project partners & funding bodies: MoA, China; defra, FCO & dfid in UK
China
•CAU (Zhang Fusuo, Zhang Weifeng, Ju Xiaotang)•CAS Centre for Chinese Agricultural Policy (Huang Jikun, Jia Xiaoping•4 case study Provinces: (Shaanxi –NWAFU; Shandong; Jiangsu – CAS Institute of Soil Science & Nanjing Agricultural University; Jilin)
UK
•Rothamsted Research (David Powlson)•North Wyke Research (David Chadwick) •University of East Anglia (Lu Yuelai)