近30a垫江县基本与非基本农田有机碳动态演变分析

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

基本农田土壤有机碳密度(soil organic carbon density,SOCD)及其变化理应高于非基本农田,但受"保增长"的强势作用,基本农田SOCD及其变化,常常出现相反的结果。该文以1980s第二次土壤普查、2011年样点实测数据、2011年基本农田保护图等为基础,使用土壤类型法,对垫江近30 a基本与非基本农田SOC进行比对,结果表明:1垫江基本农田SOCD,在1980s和2011年均低于非基本农田,分别为682.89和365.75 kg/hm2。不同截面年份SOCD净增量为:基本农田>非基本农田,近30 a基本农田SOCD增幅为11.28%。2基本与非基本农田SOCD和SOC储量,在1980s和2011年均展现出显著的空间差异,近30 a基本农田SOCD年均增加速率为(79.56 kg/(hm2·a))高于非基本农田的(68.99 kg/(hm2·a))。3基本农田与非基本农田在近30 a间的固碳、相对平衡和丢碳面积比,并未展现出显著差异;基本农田固碳和相对平衡的累积比,仅略高于非基本农田,分别为62.73%和61.98%;基本农田与非基本农田固碳、相对平衡和丢碳的空间格局,与相应的SOCD年均变化速率一致。4近30 a基本与非基本农田SOCD年均变化速率的主要影响因素表现为:1980s的SOCD SOCD1980s>全N密度>C/N比,受地形因子和土壤管理因素的影响相对较小。其中,SOCD1980s拥有负向影响作用,全N密度和C/N比则恰恰相反。该研究可为基本农田划定提供参考。

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 consmnption, 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%）, aeidifieation/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 reduee 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.