Effect Of Nitrogen Application Rate On Soil Nitrate Content And Crop Nitrogen Use Efficiency Under Sprinkler Irrigation

Excessive and irrational nitrogen fertilizer has no effective increase in the wheat, corn grain yield and nitrogen uptake, but caused a lot of nitrogen to leak to the surrounding environment, threatening the safety of the environment. Therefore, in order to find the appropriate level of nitrogen application which are of great significance on agricultural production as well as ecological and environmental protection,we will do research on the soil migration and distribution of nitrogen and the impact of different nitrogen levels on indicators of crop growth, yield and nitrogen use efficiency.This experiment research the impact of different nitrogen levels on crop growth indicators, production, and utilization of nitrogen fertilizer under sprinkler irrigation. Through the study by planted winter wheat and summer corn from October2009to October2010, we have the following conclusions:The nitrate is mainly distributed in the depth of100cm soil during winter wheat season. And the N accumulation reaches its maximum in0～100cm soil layer which has very good linear relationship with nitrogen application.As top-dressing twice and the arrival of the rainy season, nitrate in soil was leached to100-160cm soil layer and reached the peak in the130-150cm soil layer during summer maize season. The nitrate accumulation content in0～100cm soil layer show a downward trend. This phenomenon shows that the nitrate has been leached to the deeper soil layer. The soil nitrate nitrogen accumulation analysis of winter wheat and summer maize shows when nitrogen application more than the333kg/hm2nitrogen level, the Nitrogen application is greater than the crop uptake, which leads to soil nitrate increased rapidly.After the comprehensive analysis of the growth index of winter wheat and summer maize, we have the conclusion that the N4treatment is better than the other treatments. Also, the analysis of the production shows that the N4treatment is better than other treatments. The yield of winter wheat and summer maize are6.12t/hm2and76.79t/hm2. Considering comprehensively the yield of winter wheat and summer corn, water use efficiency and nitrogen use efficiency considerations, the recommendation single-season crop nitrogen rate of experiment area is333kg/hm2.