Analysis on livestock and poultry production and nitrogen pollution load of cultivated land during last 30 years in China

In recent decades, China's livestock and poultry industry developed rapidly, and their wastes have become an important pollution source, and made a serious threat to China's environment. Due to the significant differences in natural conditions and economic development level in different provinces or regions, the scale and speed of livestock and poultry production show a large regional differences. Based on the statistical data of major livestock and poultry in recent 30 years of main provinces in China, we studied the spatial heterogeneity and temperal changes of livestock and poultry production and their annual growth rate, and further analzed their nitrogen pollution load per cultivated land area. The studied results show that, in recent years, China's livestock and poultry industry have developed rapidly, especially in the north and northeastern of China. The average annual growth rate of pigs, sheep and poultry generally increased grealtly all over the regions, which were even more than 12%. Relatively, the regional differences of the average annual growth rate of cattle or sheep exist in China, the North and Northeast China show the most obvious growth. During the last 30 years, the livestock and poultry development process can basically be divided into three stages: the steady development stage (1980-1995), the comprehensive development stage (1996-2006), the mordern development stage (2007-present). On the whole, the nitrogen excreted by the livestock and poultry are mostly distributed in north, middle, south, and southwestern of China, especially in Henan, Sichuan and Shandong provinces. These three provinces showed the largest growth rate, breeding production and nitrogen excretion of livestock and poultry. However, at present, the nitrogen pollution load for the unit cultivated land area in the middle, south and southwestern of China are the most, the farmland and water resource in these regions are facing the most serious pollution risk. In 2009, the average nitrogen load in unit cultivated land area in China were more than 138.13 kg/hm2. And for the six provinces including Sichuan, Beijing, Guizhou, Guangxi, Yunnan and Guangdong, they were above 202.98 kg/hm2, which have exceeded the cordon of 170 kg/hm2 regulated in the European Union policy. What is more, in most of other provinces of China, the nitrogen load in unit cultivated land area are being fast close to the cordon. Therefore, to avoid the cultivated land and water environment polluted by livestock and poultry manure, it is very necessary and urgent to control and manage the livestock and poultry production with the strong measures and means, and deal with the animals manure timely and effectively. This investigation can provide scientific support to the provinces on planing agriculture development and adjusting livestock and animals breeding structure.