Carbon Footprint And Low Carbon Strategy For Grain Production In China

Current food production in China is facing three challenges including climate change,environmental pollution and food security.Integrated measures generated from technonolgies,market and management are critical to maximize the economic benefits,social benefits and ecological benefits.In this study,we estabilished a model to quantify carbon footprint of food production in different regions of China,explored how different production practices and social economic factors influenced carbon footprint and identified the optimal low carbon production strategy.1.The model for carbon footprint is build upon life cycle assessment method(LCA).The boundary composed upstream process-production of agriculture input(fertilizer,pesticide,machinery and agricultural film),farmland operation process(tillage,sowing,harvest,straw processing)and carbon sequestitration in cropland.Combinding of specific farming practices of 3240 farmer samples from 11 provinces in China's three major staple crop production regions,we quantified the carbon footprint of each regions.The results showed that from life cycing perspective,the total carbon footprint per unit area and per unit yield of three cropping system were high,i.e.4052 kg ce/ha for maize(0.48 kg ce/kg),5455 kg ce/ha for wheat(0.75 kg ce/kg),and 11881 kg ce/ha for rice(1.60 kg ce/kg)respectively.2.The main carbon emissions of grain production in China are from nitrogen fertilizer(8%-49%),straw burning(0%-70%),energy consumption for mechine(6%-40%),energy consumption for irrigation(0%-44%),methane from paddy field(15%-73%).There are large differences in regional carbon emissions,which mainly due to natural factors and farming practices,such as high methane emissions from rice paddy fields,as well as high nitrogen fertilizer input in Northwest,and straw burning in Northeast and other areas.3.This study established cost-benefit analysis method and econometric model,identified how social economic factors affected the carbon emission.This study found that synergetic improvement of economy and environment could not be achieved if following the current social development pattern.Firstly,transfering maize to Northeast China enhanced the profit and lower carbon emission;transferring maize to Northwest China will greatly increase profit however along with enomous carbon emissions.The transfer of wheat from other regions to North China plain brings benefit both for economy and environment.In double rice production system,tansfering from paddy-paddy pattern to paddy-upland system enhanced the synchroneity;While transferring rice from south China to Northest leads to greater emissions.Secondly,in farmers' level,current changing has complex influence on economy and envrironment.For examples,the aging of farmers will decrease the carbon emission and increase net profit in maize production;while the expansion of farm size significantly increased carbon emissions in maize production.4.Advanced technology is the only way to realize low-carbon agriculture in China.Through the establishment of low-carbon technology cost accounting method and Marginal Abatement Cost Curves(MACCs)method,we evaluated the total cost and environmental benefit of different technologies.The study found that:(1)In 2013,China's three major creal crops could reduce 49.62 Tg ce if adopt all six low-carbon technologies,but the payment could be up to 13.4 billion yuan.In which,nitrogen fertilizer optimization and no-tillage are Cost-saving technologies,which can reduce 5.49 Tg ce emission and saved 4.762 billion yuan.Straw returing and intermittent irrigation are cost-increasing technologies,which can reduce 26.23 Tg ce emission and increase cost by 41.8 billion yuan.(2)We used MACCs method to select regional low cost technologies.We found for maize,nitrogen optimization technology could be the best solution for most main producing regains.But for summer maize in North China Plain and spring maize in Northwest arid area and Northeast,no-tillage could be another option.Nitrogen fertilizer optimization technology is also first priority for wheat in national scale,but no-tillage could be a promising measure in double rice area.Nitrogen fertilizer optimization technology was proposed again to be top choice for rice in national scale,but intermittent irrigation technology could be imporatangt in Northeast.