spatial variations of soil ammonia and nitrate under application of inorganic and organic fertilizers in purple soil—Summer corn season
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Abstract
The temporal-spatial variations of the contents of Soil NH4+-N and NO-3-N in purple soil under different fertilization systems in summer corn seasen were analyzed.The results show that there are significantly negative correlation between the quantities of soil ammonia and nitrate; the content of soil ammonia changes in wavelike shape with the time. At the ripe period, soil ammonia behaves like ‘K’ in the profile.However,the distribution of soil nitrate is quite irregular in time and space. Rainfall and the distribution of plant roots are important factors of the movement of soil nitrate. Rainfall has a significant effect on nitrate leaching.The quantity of soil nitrate is changed by fertilization,and possibility of leaching increases. The leaching trend behaves like pure chemical fertilizer＞pure pig manure＞pig manure and chemical fertilizer＞CK.The distribution of plant roots correlates with the absorption and utilization of soil nitrate.The growth of plant roots is promoted by organic fertilizer,promoting the absorption of nutrition by roots in the deep soil layer.Under the application of organic fertilizer,nitrate is retained to move downward slowly.It is pointed out that we should pay attention to the risk that soil nitrate moves from 30～80 centimeter of soil layer and pollutes the under ground water.
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