Abstract:
In order to accurately grasp the regional differences in the development of livestock and poultry breeding in NyingchiCity and the pollution threat of livestock and poultry faeces to the environment, this study demonstrated the regional differences and spatio-temporal changes in the increase rates of livestock and poultry production and nitrogen and phosphorus pollution, and analyzed the livestock and poultry pollution load of the cultivated land by using the methods of annual average growth rate and output coefficient. The results showed that the livestock and poultry breeding industry in NyingchiCity developed rapidly, and the annual average growth rates of cattle, pigs and poultry in all the counties were generally higher. Differed from that of other livestock and poultry, the sheep showed a negative growth rate. The development of livestock and poultry breeding could be divided into three stages, i.e. steady development stage (1986−2000), comprehensive development stage (2000−2010), and modernised development stage (2010−2014). In the temporal and spatial evolution of livestock and poultry pollution load in each county of the study area, Milin County and Gongbo’gyamda County grew the fastest. Motuo County kept the minimum load all the time. Longxian County, Gongbo’gyamda County and Milin County had the greatest annual load risk per unit cultivated land area.By comparison, the amount of livestock and poultry pollution was larger in Gongbo’gyamda County, the annual average growth rates were higher in Nyingchi County and Mainling County, and the pollution loads of nitrogen and phosphorus from the livestock and poultry breeding in the unit cultivated area were the heaviest in Lang County. The average loads of phosphorus and nitrogen from the livestock and poultry breeding in Nyingchi City were 400 and 2 345 kg/hm2, respectively. The temporal and spatial evolution of livestock and poultry breeding and TP, TN in the study area were similar, and TP,TN pollutants mainly came from the cattle breeding and excretion. The total amount of TP, TN pollutants in livestock and poultry breeding in each county of the study area was different in the three stages of aquaculture development, and the fastest growth was in Nyingchi County, Milin County and Gongbo’gyamda County as a whole. Among them, the highest risk administrative districts were Gongbo’gyamda County and Longxian County, and the least risk administrative districts were Motuo County. The results showed that the TP, TN pollution load of livestock and poultry breeding per unit cultivated land area in the study area had far exceeded the warning stipulated in the agricultural policy of the European Union. Because of the dense inland river network and sensitive ecosystem in Nyingchi City, it was urgent to take scientific and reasonable measures and meant to effectively control and manage the livestock and poultry breeding industry, and to take effective measures to deal with pollutants such as livestock and poultry faeces, so as to ensure the sustainable development of livestock and poultry breeding in NyingchiCity. These results could provide scientific basis for the development planning of agriculture and animal husbandry and the structural adjustment of livestock and poultry breeding in Nyingchi City.