Effect Of Different Nitrogen Rates On The Profile Distribution Of Soil Nitrogen In No-tillage Farmland

The experiment, which is done in Lijiabu country Dingxi City, Gansu Province, and as a platform of no-tillage conditions of long-term positioning of different fertilization systems, designs the different influence on nitrogen fertilizer on soil nitrogen content and crop yield and tests the determination of long-term positioning of different fertilization systems0-200cm soil layers soil alkali-hydrolyzed nitrogen and ammonium nitrogen content and distribution, to provide a theoretical basis for the efficient use and reasonable application of nitrogen fertilizer. At the same time it studies the different nitrogen system in the no-tillage conditions to the aftereffect of spring wheat nitrogen and optimum fertilization. It provides a scientific basis for Gansu Loess Plateau hilly district rain to support the the farmland scientific and rational use of nitrogen fertilizer and increase nitrogen utilization and to assess the agricultural soil environment quality. The results are as follows:1,From started with test2004, before the sowing to P fertilizer for nitrogen fertilizer in2007, the amount of nitrogen significantly affects the0-200cm soil nitrogen content in alkali solution. In this study, the WNR+1.75processing is in the middle level on the basis of a continuous nitrogen application of the overall nitrogen content, while WNR+1.7_C processing stopped nitrogen fertilizer after a year, plants are not result nitrogen in a great loss. Although the content of each soil layer decreased, the differences among the treatments under different N levels in the same soil level soil alkali-hydrolyzed nitrogen is more significant.2,In2011before planting, surface0～10cm soil alkali-hydrolyzable nitrogen content was significantly higher than the bottom, accounting for28.82%of the whole soil total alkali-hydrolyzed nitrogen. After years of no-tillage experiment, soil nitrogen content level is maintained at moderate levels, and the surface is significantly higher than the bottom, and soil nitrogen content has obvious table poly phenomenon.3,The WNR+1.75processing which is after many years of nitrogen fertilization and the absorption and utilization of season spring wheat,2011post-harvest processing nitrogen content in0-200cm soil of alkaline hydrolysis residues is obvious:N1,11-27%; N2,-1.67%; N3,2.13%; N4,-8.66%and N5is6.19%; decline is not large while aftereffect is significant.4,On the dynamic of vertical profiles, soil alkali-hydrolyzed nitrogen content show a decreasing trend with soil depth in the whole. On average, the soil alkali-hydrolyzed nitrogen and ammonium nitrogen appears irregular "W" shape.5,In2007before planting, compared WNR+1.75processing status of0-200cm soil layer of ammonium nitrogen distribution with its significant:starting from the experiment in2004, the soil ammonium nitrogen is continuously applied to three years of the nitrogen on the basis of the content of the existence of significant differences. The distribution of soil ammonium nitrogen content tended to increase with the increase in ammonium nitrogen content of soil depth. WNR+1.75_C with P fertilizer N treatment2years continuous, stop year nitrogen before planting soil layer determination:in the0～5cm,80～110cm there are significant differences among treatments, other ammonium nitrogen content of soil was no significant difference between each treatment.After consecutive years of spring wheat continuous cropping stopped after five years of continuous nitrogen fertilization with P fertilizer nitrogen application before sowing (2011) the differences in changes of soil ammonium nitrogen content is not very significant, WNR+1.75processing, only between170～200cm at each treatment there are significant differences, significantly higher than the N1and N2treatment,61.00%higher than the N1treatment, and other differences between the treatments is not significant among treatments of each soil layer. The WNR+1.75_C handle50～80cm,170～200cm soil ammonium nitrogen content was significantly difference between the other layers of the differences among the treatments was not significant.WNR+1.75_C processing after the2011harvest, after the season's crop uptake and utilization, compared to WNR+1.75processing differences between the soil handling significantly reduced only in the10～30cm and170-200cm soil layer of the soil ammonium nitrogen there is a very significant difference, at50～80cm, N2s processing also significantly higher than the Nls handle and deal with43.26percent higher than the Nls;110～140cm, N1s, N3s, handle significantly higher than N2s processing, representing ann2s handle high of71.86%and72.46%respectively. The other floors were no significant differences between each treatment.6,Spring Wheat in the Loess Plateau of Field of Gansu using of nitrogen fertilizer on yield has significant residual aftereffect.In different levels of nitrogen, its production are increase with the growth of fertilizer levels and in a certain point it begans to decline, and will not continue to grow, fertilizer and yield appears a quadratic relationship. And high nitrogen amount will decrease the efficiency of nitrogen and this will be resulting in lower yields. The study shows that it will reach the highest production when the N is105kghm-2.