Carbon Footprint Life Cycle Assessment Of Pig Feed

Climate change is widely considered to be the greatest challenge facing humanity,so it is urgent to take steps to mitigate climate change.Agriculture has huge potential to achieve"peak carbon"and"carbon neutral"goals.China is a large country in livestock and poultry breeding,and feeding animals consumes a large amount of feed.However,greenhouse gases are generated in each stage of feed cultivation,processing,utilization,treatment and transportation.Therefore,it is very necessary to understand the greenhouse gas emission and its emission reduction potential of feed life process.The key to reducing greenhouse gas emissions from pig farming is to improve the efficiency of feed utilization.However,at present,few domestic and foreign studies regard feed as the key core link of greenhouse gas emissions from pig breeding,and carbon footprint studies are carried out around the life cycle process of pig feed.There is a lack of accounting methodology and accounting model for pig feed carbon footprint that match China’s national conditions.In this study,the Life Cycle Assessment（LCA）method is used to calculate and evaluate the carbon footprint of pig feed.System boundaries include feed crop cultivation,feed processing,feed use（pig feeding）,waste disposal（manure,bag management）and transportation between them.After the feed is used by pigs,part of nutrients not absorbed by pigs,but remain in feces excreted out,part of the nutrients into pork,pork will continue to be generated by the downstream link to use,but not in the study of pork using phase of carbon emissions and calculation,so this study is a part of life cycle assessment.The functional unit is 1t pig feed;The time range is 1 year,the feed crop planting period;Distribution mode selection value distribution;The greenhouse gases are evaluated as CO₂,CH₄ and N₂O.Establish an accounting formula of carbon footprint through model construction and reference to relevant guidelines and standards.Taking a planting enterprise,a feed enterprise and a breeding enterprise as empirical objects,and combining with the actual situation of planting and breeding in China,various factors affecting the carbon footprint of pig feed life cycle process are analyzed,and the impact of feed life cycle on climate change is obtained.Scientific accounting assessment of China’s feed carbon footprint,the development of low-carbon and emission reduction strategies,to provide reference and technical support for enterprises to reduce greenhouse gas emissions,in order to contribute to agricultural emission reduction.The main conclusions are as follows:（1）In this study,biogas residue and biogas slurry generated by biogas engineering of waste disposal unit is used as organic fertilizer in maize planting process,and the fixed greenhouse gas content of soil is 324.43 kg CO₂-eq and the greenhouse gas offset rate is28.94%.Meanwhile,the greenhouse gas emissions from upstream production of fertilizer are reduced,partially realizing carbon neutralization of greenhouse gas.（2）When soil carbon sequestration is included in the accounting boundary as an offset,1t pig feed carbon footprint is 796.54 kg CO₂-eq,and 1kg pig live gain consumes 2.805 kg feed,equivalent to 2.23 kg CO₂-eq/kg pig weight gain.The GHG contribution rates of feed crop cultivation,feed processing,feed use（pig feeding）,waste disposal and transportation are30.50%,3.17%,10.82%,44.03%and 11.48%,respectively.Waste disposal,feed crop cultivation and transportation are the main GHG contributing units,while the main GHG emission sources are manure management,fertilizer application and transportation fossil fuel combustion.（3）When soil carbon sequestration is not included in the accounting boundary,1t pig feed carbon footprint is 1120.97 kg CO₂-eq,pig live gain of 1kg consumes 2.805 kg feed,and pig weight gain of 3.14 kg CO₂-eq/kg is generated.It is consistent with other research results.（4）The main GHG contribution processes of each unit are:fertilizer application,fossil fuel combustion,compound fertilizer production and electricity use in feed crop cultivation unit;Feed processing units for use of electricity and fossil fuel combustion;Feed use（pig feeding）unit use of electricity and intestinal fermentation methane emissions;Manure management in waste disposal units;Energy consumption of transport units.（5）Put forward specific emission reduction measures and strategies according to the main GHG contribution process.According to the identification results of the main process of greenhouse gas emission,the emission reduction measures are formulated,including the remaining time in the waste disposal unit and the control of manure shed is 1 month,the greenhouse gas emission reduction rate of the unit is 64.24%;In the feed crop planting unit,the soybean crop yield and soil carbon sequestration are increased by reducing the fertilizer application by half and applying organic fertilizer 1t/mu,and the greenhouse gas emission reduction rate of soybean planting is 84.98%.The transport unit controls the transport between materials within 30 km,and the greenhouse gas emission reduction rate of the unit is94.47%.If the above conditions are met at the same time,the greenhouse gas emission of the whole study is reduced from 796.54 kg CO₂-eq to 232.37 kg CO₂-eq,and the maximum emission reduction potential is 70.83%.