关键词: 化肥使用强度, 环境安全阈值, 环境风险评价, 区域差异, 中国

Abstract: 【Objective】 Studies on distribution and environmental risk of fertilization in China were made in order to fully recognize the differences in provincial agricultural fertilizer use, its potential threats to the ecological environment and the degrees of environmental risk, and realize the sustainable development of Chinese agriculture. 【Method】 Considering the different impacts of N, P, K fertilizers on environment, a model of fertilization environmental risk assessment was established with weight coefficients to assess the fertilization environmental risk of China. Analystic hierarchy process (AHP) was used to determine the weithts of N, P, K. The environmental safety thresholds of N, P, K was made according to the standard of 250 kg·hm^-2 for the construction of ecological counties sponsered by Chinese government and the proportion of 1﹕0.5﹕0.5 for N:P:K surposed by some developed counties. 【Result】Results showed that, at present the rate of farmland fertilizer in China reached 480 kg·hm^-2, farmland fertilizer input in most provinces was overloaded. The basic trend was that the southeast part of China puts much more fertilizers onto the farmland than the part of northwest. The first five provinces, whose fertilization intensities were greater than 690 kg·hm^-2 in 2012, were Fujian, Guangdong, Henan, Hubei and Jiangsu, while the last seven provinces, whose fertilization intensities were less than 200 kg·hm^-2, were Tibet, Qinghai, Gansu, Heilongjiang, Guizhou, Inner Mogolia and Shanxi. The greatest amount of fertilization, 908.7 kg·hm^-2, was in Fujian, 6.6 times greater than that of Tibet (137.99 kg·hm^-2). Unbalanced proportion of NPK use was obvious in China. The intensity of nitrogen fertilizer use in Guangdong province was 448.5 kg·hm^-2, 7.2 times greater than that of Tibet (62.59 kg·hm^-2); Phosphate fertilizer input in Henan was as high as 259.8 kg·hm^-2, 6 times greater than the lowest one of Guizhou (44.04 kg·hm^-2); Potash input in Fujian was up to 264.73 kg·hm^-2, 8.6 times greater than the lowest one of Qinghai (30.83 kg·hm^-2). China's agricultural fertilizer intensity resulted in the potential risk of environmental pollution. Except for five provinces of Tibet, Qinghai, Guizhou, Gansu and Heilongjiang, which were at safety status, three provinces of Henan, Fujian, Guanddong and Hubei were classified as being severe risk from fertilization, while the rest of provinces were classified as light risks or medium risks. 【Conclusion】 Overuse of fertilizer is significant in China and resulted in severe environmental risk. Several reasons were concluded. Soil condition, fertilization technology and mismanagement were the direct causes for the overuse, while agricultural policies and management system were the fundamental ones.

Key words: intensity of fertilization, environmental safety threshold, environmental risk assessment, provincial difference, China