The Research Of Livestock Carrying Capacity Of Hunan Province Based On Crop—Animal Mixed Farming System

After continuous years of rapid development, the livestock industry of China, has made remarkable achievements.The development of the livestock industry while improved the people’s living standards, it also to brought enormous pressure to environmental protection. In recent years,with the increase of breeding scale and the transformation of operation mode, the livestock industry’s breeding structure has made a conversion from traditional retail to intensive raising.The large amount of pollutants produced by intensive raising not only impact on the living environment of livestock, but also cause serious harms to the air, water, soil and human health.This research, being directed against irrational breeding structure and high cost of pollution removal facilities, showed a link between livestock breeding and agricultural planting and based on the theory of crop—animal mixed farming system, preliminarily calculate the pollution carrying capacity and forecast the development space of livestock industry based on the current agricultural cultivation conditions. The main results are as follows:(1) The main agricultural reuse of the wastes from livestock breeding in Hunan Province is farming farmland and ecological forests.Selecting rice, corn and soybeans etc. as the main commercial crop varieties in Hunan Province, then explicitly define its nitrogen absorption amount for every100kg of yields as well as the annual demands for nitrogen from organic fertilizer per tree in the ecological forest. Combined with the main varieties of crop yields and ecological forest area in "The Hunan rural statistical yearbook of2011", figured out the total nitrogen demand for the planting industry in Hunan Province is0.989million tons.,and the nitrogen demand for ecological forest in Hunan Province is0.065million tons.(2) The main types of planting soil of Hunan Province are red soil, yellow soil, paddy soil,purple soil and calcareous soil, through the actual inspections and measurements of the effective nitrogen as well as its proportion in these kinds of soil, calculated its weighted average as the average content of effective nitrogen for the soil of Human Province, therefore concluded the average soil nitrogen supplying capacity is18.38kg/mu in Hunan Province. Through analysing the cultivated land and garden area in various cities of Hunan Province from "The Hunan rural statistical yearbook of2011" and obtained the total planting area is64.528million mu in Hunan Province and the actual soil nitrogen is0.593million tons,under the condition that the soil nutrient coefficient is0.5.(3) It choosed pig,beef cattle,dairy cow,laying hen,broiler as the main varieties of livestock and analyzed its pollutants producing coefficient.The results showed that: the pig’s pollutants producing coefficient (kg/head) COD46.33>TN3.78>NH3-N1.95>TP0.57; the beef cattle’s pollutants producing coefficient (kg/head) COD1795.56>TN73.76>TP8.96>NH3-N2.51; the dairy cow ’s pollutants producing coefficient (kg/head·a) COD2062.37>TN104.14>TP16.50>NH3-N3.09; the laying hen ’s pollutants producing coefficient (kg/head) COD4.63>TN0.50>TP0.12>NH3-N0.11; the broiler’s pollutants producing coefficient (kg/head) COD1.46>TN0.06>TP0.02=NH3-N0.02.Combined with the numbers of livestock in various cities,it showed that the pollutants of livestock industry of Hunan Province reached a total volume of92.8525million tons.(4) It divided the14cities of Hunan Province into124geographical units and undergone investigations.The results showed that:Currently,pollution removal facilities of Hunan Province have three typical patterns (The pattern of fecal pollution to field, The pattern of anaerobic fermentation—agricultural utilization and The pattern of standard discharge); practical testing by mode decomposition was carried out against each unit’s processing efficiency,and the livestock pollutants TN average removal efficiency at the rate of30%was derived.(5) According to the above conclusion,the carrying capacity of various cities in Hunan Province is maximally191.887million equivalent pigs,still have a supplementary carrying capacity of65.146million equivalent pigs under the circumstance that the amount of nitrogen fertilizer holds45%of the total amount of fertilizer.The serious pollution areas are mainly concentrated in the central and Western of Hunan Province.There are certain development space still existing in the central of Hunan Province.And there are a larger space for development in the northeast and south of Hunan Province.