Carrying capacity of livestock and poultry breeding based on feces disposal volume of land

Abstract: The livestock and poultry breeding industry in Pinggu district of Beijing developed rapidly. Compared with 1992, the slaughter of pigs and chickens increased by 18.95% and 22.29%, and the breeding stock of cattle, sheep, laying hens increased by 35.51%, 40.28% and 10.29%, especially the pig slaughter and egg production, which occupied by 11.81% and 20.21% of Beijing respectively. Gradually, the environmental pressure appears caused by the rapid growth of livestock and poultry manure quantity. And Pinggu district, the ecological conservation district, ecological barrier and water source protection of Beijing, is of a great importance to keep the environment of Beijing sustainable and healthy. As a result, it is important to connect farming and aquaculture, construct the circulation of agriculture economy chain, and determine the scale of farming according to local conditions. Based on the characteristic that orchard land took a large part of agricultural land, this paper set the cultivated land and orchard nitrogen limited standard, through calculation of the environmental capacity of farmland nitrogen, the poultry and animal feces pollution risk index and potential of livestock and poultry, then assessed the livestock carrying potential and potential contamination and analyzed the farmland and orchards' livestock carrying potential of Pinggu and its town. The results indicated that: 1) During 2012, the total manure of Pinggu was 591 100 tons, containing nitrogen and phosphorus respectively 4 721, 998 t, which meant a huge organic resource, made it available to reduce the fertilizer use, and can effectively improve soil quality and the quality of the crops; 2) For ecological conservation development area, as the orchards occupied a large proportion of agricultural land, the agricultural land of livestock and poultry manure loading status achieved by taking the cultivated land and orchard as disposal site, may be more practical. The average manure load of agricultural land was 16.7 t/hm2, lower than the national standard of 30 t/hm2, and the orchard manure load accounted by 66.42%; If only taking the cultivated land as the consumptive manure carrier, the amount of agricultural land manure load was 49.74 t/hm2, far higher than the national standard; 3) The potential of livestock and poultry in Pinggu district, which were 62.5 and 94.8 thousands pigs' equivalent for nitrogen and phosphorus respectively. Totally speaking, the district was available for bearing livestock and poultry, but the difference was significant among each town's agricultural land: Xinggu, Yukou and Daxingzhuang, etc, were carrying excess, however, Dahuashan, Zhenluoying and Xiongerzhai, etc, still had great potential consumptions of livestock and poultry manure. Among them, Xingu region has greatly exceeded the carrying capacity of agricultural land, so it's urgent to control the overall amount and take measures to make resources of animal manure harmless and ecological. According to that, taking the town as the basic research unit, can effectively reflect the strong spatial differences of the regional livestock carrying capacity, and also can be helpful to formulate the livestock differentiated control strategies and measures for the development of livestock excreta disposal. However, the consumption of livestock and poultry excrement of farmland is not only influenced by agricultural land use types, but also by other factors such as soil physical and chemical properties, topography, the using way (bare and protected area), planting patterns and fertilization habits and so on. Obviously, the spatial differentiation does exist. As a result, more detailed data is in urgent need to achieve more scientific and accurate results and so as to provide support in selecting a proper site and layout for livestock and poultry breeding industry.