Dynamic changes of soil organic carbon for basic farmland and non-basic farmland of Dianjiang county in recent 30 years

The negative impact of livestock production on the environment is a concern, and thus it has been one of the major constraints on the development of animal production in some regions. Life cycle assessment (LCA) approach is a useful technique to assess environmental impacts associated with all the stages of a product life cycle from cradle to grave. At present, SimaPro software, which is developed on the basis of life cycle assessment framework, has been applied for analyzing environmental burden by different impact categories. It has been widely used in the study of sustainable development of animal husbandry around the world. The Eco-indicator 99 is a damage-oriented approach for life cycle impact assessment, which can be used to calculate the damage caused by the pollutants on human health, ecosystem and resource consumption via air, water and soil. The main objective of this research was to systematically evaluate the environmental impact of intensive pig production in Hubei province by a comprehensive method. Thus, based on the theory of Life Cycle Assessment (LCA) and SimaPro software (Version7.1.8)，as well as Eco-indicator 99, we assessed the burden of intensive pig production on environment in Hubei province. Four key links were divided on the basis of input types of corresponding materials and the main characteristics of pig production, including piglet production, feed consumption, routine management, and waste treatment. Based on life cycle theory, we took weaning piglets as a carrier to share the corresponding environmental impact caused by resource consumption and pollutants emissions from feeding sows. In this research，feed consumption was referred as land occupations, crops planting, investment of fertilizers, pesticides and agricultural machineries. Routine management was the water, and power consumption, and the treatment of harmful gases, like NH₃, CH₄, CO₂ and N2O in pig houses. Piggery waste treatment included composting manure and sewage by anaerobic fermentation. The results showed that the single score of environmental burden in pig farming systems was 45.13. The results also showed that the impact categories were land occupation (59.84%), respiratory system damage caused by inhaled inorganic matters (14.29%), fossil resource consumption (9.97%), carcinogens (7.80%), acidification/eutrophication (5.18%) and climate change (1.90%). Meanwhile, the stage of piglets breeding accounted for 17.91% while fattening stage after weaning took up 82.09% in the single score of environment burden. Furthermore, piglet breeding and feed consumption during the period of fattening stage after weaning made great contributions to land occupation and carcinogens, while daily management and manure treatment were the two main contributors towards respiratory system damage caused by inhaled inorganic matters, acidification/eutrophication and climate change. Finally, the routine production management largely affected human health while waste treatment affected least. Feed consumption had the greatest influence on ecological quality and resource consumption, and dung treatment process had the least. Therefore the best way to reduce the burden of intensive pig farming system on environment in Hubei province was, on one hand, to improve the reproductive performance of sows, feed conversion, the yield of crops and the utilization ratio of manure; and on the other hand, to reduce the consumption of chemical fertilizers and the dosage of pesticides.