Analysis Of Land Carrying Capacity Of Livestock Manure In Chengdu City Based On Nitrogen Balance Principle

Chengdu has a large amount of livestock and poultry raising scale and produces lots of livestock and poultry waste.Due to the imperfect treatment facilities,immature treatment and utilization technology and mismatched breeding and raising,the pollution of livestock and poultry occurs from time to time.Under this background,how to dispose of livestock and poultry wastes harmlessly and utilize them as resources has become one of the research focuses of the current aquaculture industry.Based on the principle of nitrogen balance,a formula for calculating the carrying capacity of livestock and poultry farming land was put forward,and the carrying capacity of livestock and poultry farming waste land and the carrying capacity of livestock per unit land area of different crops in Chengdu in the past five years(2013-2017)were analyzed.Results are as follows:a.The land carrying capacity of livestock and poultry raising waste in Chengdu from2013 to 2017 was 0.71,0.71,0.67,0.66 and 0.65 respectively,showing a decreasing trend year by year,and all of them were less than 1,indicating that the number of livestock and poultry farming did not exceed the maximum amount of land can carry.If livestock and poultry raising waste were treated and utilized reasonably,the risk of environmental pollution would be smaller.b.According to the actual situation of livestock raising and planting in Chengdu,the maximum pig carrying capacity from 2013 to 2017 was 16.3190 million,16.0071 million,16.8405 million,20.5548 million and 19.9690 million respectively.c.In pig equivalent unit,the land carrying livestock capacity in unit land area of rice,wheat,corn,soybean,potato,oil and vegetable in Chengdu is 3.80 head / mu,2.80 head /mu,2.66 head / mu,3.91 head / mu,0.40 head / mu,3.73 head / mu and 2.88 head / mu respectively,in the condition that the cultivated land is in plain area and the distance from the farm area is less than 10 km.d.In pig equivalent unit,under the constraint of the distance between cultivated land in plain area and the farm area is less than 10 km,β=0.50,which is to say under the condition that the actual production amount of livestock and poultry waste is fully recycled in the current situation in the city of Chengdu,the land carrying livestock capacity in the unit land area of wheat,corn,soybean,potato,oil and vegetable is 1.90 head / mu,1.40 head / mu,1.33 head / mu,1.95 head / mu,0.20 head/mu,1.86 head/mu and 1.44 head/mu respectively.e.The land carrying capacity of livestock and poultry raising waste is affected by the number of livestock and poultry raising,the amount of nitrogen fertilizer applied,the content of soil nutrients,the types of planting plants and the use efficiency of fertilizers.It is necessary to control all factors through comprehensive measures so that the waste can be accurately returned to the field according to the principle of nutrient balance and recycling,thus reducing the risk of environmental pollution caused by livestock and poultry raising waste.