Mitigation Of Ammonia Emissions Of Intensive Animal Farms In Jing-Jin-Ji District And Their Benefit

With the rapid development of the economy,the increasing demand for livestock products has promoted the rapid development of the livestock and poultry production,and the resulting large amount of livestock and poultry manure and urine will cause excessive ammonia emissions and cause a series of ecological and environmental problems.In order to alleviate the pressure on the environment caused by ammonia emissions from the livestock production,and provide technical recommendations achieving efficient and economical ammonia emission reduction for government and farm managers,this paper designs an AGRIT model for calculating ammonia emissions from farms on the basis of the NARSES model.The newly established model is able to predict ammonia emissions of animal operations with the future local weather data.Afterwards,the AGRIT model is used to calculate the current status of ammonia emissions from livestock farms of different sizes in Jing-Jin-Ji district.In addition,scenario analysis is used to evaluate their effectiveness of the combined mitigation practices for different manure management sectors on ammonia mitigation.According to the comprehensive evaluation of emission reduction efficiency and economic benefits,the best ammonia emission reduction technology combination suitable for different animal operations,the main conclusions are as follows:(1)Estimation by the AGRIT model shows that:the daily ammonia emissions of the farm increase with the air temperature;The emissions in January and December are the smallest in one year,and the emissions from June to August are the largest.In the process of feed nitrogen flow,greatest N losses occurred at the animal housing sector,followed by the sector of field application,and the least loss is the manure storage sector.In addition,the model can predict the confidential variation of projected ammonia emissions from farms based on future local weather data,and provide sufficient statistical analysis regarding ammonia emissions for policy making.(2)In Jing-Jin-Ji region,no significant relations between the farm sizes and their ammonia emission factors are found,and the emission factors for dairy cattle,beef cattle and pig are estimated to be 35.12,23.87 and 1.50 kg/head.respectively,and approximately 380.67 and 46.50 g/head for laying hens and broilers.respectively.In addition,currently the emission rates of 93.33%of the dairy farms.16.67%of the pig farms and all farms of beef cattle,layers and broiler are greater than their respective baseline emissions,highlighting the importance of mitigating ammonia emissions.(3)According to the modeled results from AGRIT,the maximum mitigation potential for dairy,beef,pig,layer and broiler farms in Jing-Jin-Ji district are estimated to be 72.16%～73.03%,55.81%～57.65%,72.54%～82.79%,82.07%～87.47%and 84.70%～85.16%,respectively.(4)With the integrative analysis over the mitigation potential,cost and the corresponding benefit,management practices that can achieve ammonia mitigation by approximately 50%and are with greater benefit than the investment cost are identified.The recommended management scenario for large dairy farms is "Scenario feed additives+solid film coverage+oxidation pond coverage",and the recommended management scenario for medium and small farms is the scenario "Feed chemical additives+compost coverage";large The recommended management scenario for beef cattle farms is scenario feed additives+solid film coverage+composting+oxidation pond coverage,small farms are scenario low protein+feed additives+composting+oxidation pond coverage;scenario feed additives+solids Film covering+compost covering+oxidation pond covering is suitable for large and small pig farms.The recommended management scenario for medium-sized farms is the scenario of low protein+slatted floor+solid film covering+compost covering+oxidation pond covering;large and medium layer laying hens The recommended management scenario for the farm is the scenario low protein+feed chemical additives+solid film coverage+composting,the small farm is the scenario low protein+feed chemical additives+solid film coverage;the recommended management scenario for the broiler farm is the scenario low protein+Feeding room chemical additives+composting.Overall,in Jing-Jin-Ji district,there are weak relations between farm sizes and their ammonia emission factors,layer and broiler farms are found to be with the greatest mitigation potential,followed by the dairy and pig farms,while the beef farms show the least mitigation potential.Despite the difference of mitigation practices among different animal farms,a whole-chain management across "feed+animal house+manure storage"is considered necessary to successfully achieve the ammonia mitigation targets.