Life Cycle Assessment Of Dairy Cattle Feed Crops In Guanzhon Plain

Animal husbandry is an important source of anthropogenic environmental pollutants,and feed crop production is one of the main sources of environmental pollutant emissions.At present,there is little research on the life cycle assessment of dairy cattle feed cultivation and production process.Based on the theory of life cycle assessment,the dairy cattle feed crops were evaluated in Guanzhong area of Shaanxi Province.This paper studied the life cycle assessment model of dairy cattle feed production in Guanzhong Plain,evaluated the environmental impact characteristics of different dairy cows' feed crops,and analyzed the environmental impact of dairy cattle feed the main pollution and pollutants,to explore the chemical fertilizer,water conservation,farming methods of environmental impact potential,And the sensitivity of the evaluation results was analyzed in order to provide theoretical support for the realization of the clean production of feed crops and the impact of the national "grain improvement" project on the environmen.The conclusions of the study are as follows:(1)According to the basic data obtained from investigation,using LCA evaluation method,the evaluation results are follows: the potential values of production of global warming(kgCO2/kgDM),acidification(kgSO2/kgDM),eutrophication(kgPO43-/kgDM),photochemical ozone synthesis(kgC2H4/kgDM)and energy utilization(MJ/kgDM),land use(m2/kgDM),the utilization of water resources(m3/kgDM)from production of 1kg dairy feed dry matter were: Energy feeds(287.102 ~ 752.085?1.795 ~ 5.773? 0.510 ~ 1.469?0.073 ~ 0.123?2.311 ~ 5.780? 0.580 ~ 1.528?0.158 ~ 0.521);Protein feeds(589.352 ~ 935.775?4.710 ~ 9.369?0.942 ~ 1.890? 0.412 ~ 0.813?7.299 ~ 7.764?0.773 ~ 2.904?0.171 ~ 0.765);Roughage(86.698 ~255.326?0.655 ~ 4.943?0.165 ~ 1.138?0.014 ~ 0.130?0.668 ~ 2.156?0.180 ~ 1.091?0.061 ~ 0.703).Besides alfalfa,the environmental effects of energy and protein feed were higher than that of roughage.(2)The results showed that the production and field application of chemical fertilizers were the most important pollution in the process of forage crop cultivation,accounting for 39.1% ~ 68.0% of the global warming potential,57.2% to74.8% of the acidification potential,83.4 to 92.4% of eutrophic potential.12.2% to 61.4% of photochemical ozone synthesis potential.The use of chemical fertilizers is highly correlated with global warming?eutrophication and acidification potential.Irrigation is an important link in the production of pollutants from feed crops,accounting for 22.5% to 30.8% of the global warming potential,8.0% to 36.0% of the acidification potential,4.8% to 19.8% of photochemical ozone.The contribution rate of agricultural machinery to photochemical ozone synthesis is about 48.4% to 91.6%.Other aspects of the impact of smaller.The main pollutants of global warming are CO2,mainly from fertilizer production and energy production;acidification of the main pollutants is NH3,mainly from nitrogen fertilizer field application of ammonia volatilization.Eutrophication is the most important pollutants are NO3-and NH3,mainly from the nitrogen fertilizer field application of ammonia volatilization and nitrogen leaching loss of N-NO3 emissions.Photochemical ozone synthesis is the main pollutant CO,mainly from fossil raw materials combustion.(3)The results showed that themitigation potentialof cotton,corn,wheat and alfalfa according to the recommended fertilization,the environmental impact potential could be reduced as more than 8%,except photochemical ozone synthesis?Mitigation potential of green forage maize ?soybean and rape was not obvious,no more than 5%.Eutrophication and photochemical ozone synthesis of mitigation potential is minimal when the feed crops in accordance with the recommended amount of irrigation,global warming and acidification have great potential for emission reduction,but none of them exceed 16%;With irrigation methods of drip irrigation and sprinkler irrigation,if the pollutant emission of pipeline is not taken into account,the emission reduction potential of maize ?wheat and alfalfa between 0.9% and 12.1%.However,if considering the pipeline production of pollutant emissions,then drip and sprinkler irrigation without any mitigation potential,even increased the emissions of pollutants.The drip irrigation and sprinkler irrigation measures will reduce the amount of water consumption,but increase the emissions of photochemical ozone synthesis.If the conservation tillage was applied for the feed crop production process,compared with conventional tillage,the potential value of global warming,acidification,eutrophication,photochemical smog synthesis from wheat,rape,soybean,cotton,alfalfa could be reduced 5.3%~26.6%,and the mitigation potential was significant.(4)Sensitivity analysis was carried out on the effects of different planting links,different basic data sources and GWP characteristics of different years on the environmental impact potential.The difference of environmental impact potential of different chemical fertilizers was significant,and the amount of fertilizer used in feed planting was the most sensitive to environmental impact.The environmental impact potential(1 functional unit)of the dairy cows' feed crop from “National Compendium of Cost and Revenue of Agricultural Products” was significantly different from that of the survey data,and the yield was more sensitive to the environmental impact potential.The global warming potentials of IPCC1996 and IPCC2013 were significantly different(except for alfalfa),and the N2 O eigenvalues were most sensitive to the global warming potential of dairy cows.