甘肃不同生态区化肥施用量对农业环境的影响

Impacts of Chemical Fertilizer Application on the Agricultural Environment in the Different Ecological Regions in Gansu Province

依据甘肃省农业生态区划 ,对 5个生态区单位面积化肥施用量现状和年际变化及化肥产出率进行了分析。结果是 :各区化肥施用量的年变化均呈上升趋势 ,化肥施用量越高的地区 ,年平均增长率越低 ;5个农业生态区中 ,有 4个区的化肥施用量超过了全国高施肥量区 ;自 2 0世纪 90年代末各区每 1kg化肥仅生产 4 .6～ 5 .1kg粮食 ,比全国高施肥量区每 1kg化肥生产 11.71kg粮食的水平低 1.5 5倍。对环境的影响是地力受损 ,有效营养元素失衡 ,土壤板结 ,保水保肥能力下降 ;地表水和地下水受到了污染 ;部分地区农作物硝酸盐和亚硝酸盐的含量超标。

Gansu Province is located in northwest China, it is in shortage of water resources due to the limited precipitation, and the natural conditions for the agricultural production are poor. In order to increase the grain yield, more and more chemical fertilizers are applied in the province. This paper analyzes the applied quantity of chemical fertilizers per unit area and its interannual change as well as the increase ratio of applying chemical fertilizers in the five ecological regions based on the agro-ecological divisions in Gansu Province. The results show that the annual applying quantity of chemical fertilizers in the province is increased year by year, the higher the applying quantity of chemical fertilizers is, the lower the increase ratio of grain yield will be. Among the five agro-ecological regions, the applying quantity of chemical fertilizers is much higher in four agro-ecological regions than the average of the whole country. In these regions 4.6～5.1 kg grains can be produced only by applying chemical fertilizers for 1 kg, which is 1.55 times lower than that in other places where 11.7 kg grains can be produced by applying chemical fertilizers for 1 kg. The application of chemical fertilizers in such high quantity results in the serious reduction of soil fertility, unbalance of effective nutrient elements, soil hardening, decrease of water conservation capability of soils, pollution of surface water and groundwater, over-content of nitrate and nitrite, etc.