Study On Distribution Of Soil NO₃^-1-N And Utilization Rate Of Cotton By Different Ways Of Fertigation

In the process of crop growth and yield formation, the influence of nitrogen plays an important role in macro elements. Cotton yield in Xinjiang is account for more than 30% of the total cotton yield, so Xinjiang is the major cotton production and export base of China. The production of cotton mainly depends on the increase of fertilizer, especially application of the large amount of nitrogen fertilizer. However inputting a large of unreasonable nitroge n fertilizer, not only increasing the production cost but also intensified the pollution of groundwater resources. Cotton nitrogen absorption under drip irrigation is influenced by many factors, such as nitrogen strategy, the distribution of nitrate nitrogen and moisture in the soil, they all have a major impact in nitrogen absorption and utilization process of cotton.This test processed in Shihezi university agronomy comprehensive experiment stations in 2013 and 2014. In the case of same fertilizer and irrigation water, the experiment set up two different ways of fertilizer(variation in drip irrigation fertilization method and differential pressure of fertilizing). There were five kind of fertilization models under each fertilization way(W-N-W, N-W-N, W-N, N-W, WN, CK). Cotton breed was Xinluzao 48(XLZ48). In four of the cotton growth period(Sheng Lei period, coated, S heng Ling period, boll opening period), we measured moisture content and the content of nitrate nitrogen in 0~60 cm soil layer under different fertilization mode. And we proved the change rule of soil moisture content and nitrate content change with the increasing of soil depth under different fertilization patterns of the two types of fertilization; And we measured cotton nitrogen use efficiency of the cotton growth period under different fertilization mode, then through the analysis of the significance, finally got the difference of cotton nitrogen utilize of two kinds of fertilization under different fertilization pattern. Determinate the cotton yield when harvest. Results showed that:(1)Cotton growth periods, and the differential pressure type of variable rate fertilization between two fertilizer fertilization methods, with the increase of soil depth, there was no significance between the soil moisture content of each corresponding fer tilization model. Two kinds of fertilizing had no effect on soil water distribution.(2)Between different fertilization models, as the depth of soil increased, soil moisture content under the W-N-W fertilization model decreased at first and then increased; soil moisture content under the N-W-N fertilization model increased at first and then decreased as the depth of soil increased; soil moisture content under the N-W model increased as the depth of soil increased; soil moisture content under W-N, WN and CK all increased as the depth of soil increased. N-W-N fertilization model can regulate the distribution of soil moisture, keep soil moisture in the soil(20~40 cm), and benefit for the absorption of root system of cotton.(3)The fertilization effect is better than that of differential pressure type of variable rate fertilization, the implementation of variable rate fertilization the multiple small applied in fertilizer, make N slowed down; Variable fertilization under diffe rent fertilization pattern of soil NO3-1-N content change rule more slowly, so that to improve the uniformity of distribution of nitrogen in the soil, also reduces the risk of nitrogen leaching losses with the water, reduce the pollution of groundwater.(4)W-N-W fertilization mode, soil NO3-1-N content have been increased after decreased overall trends, a peak at 40 cm, 40 cm soil layer, and a slow increase, increasing the risk of nitrate leaching with the water. Compared with W-N-W, N-W-N fertilization model can regulate the distribution of soil NO3-1-N, in the soil in the middle of the soil(20~40 cm) accumulation, help the absorption of cotton root system, improve the ut ilization rate of nitrogen. W-N fertilization mode made the nitrate nitrogen in t he upper soil accumulation; N-W is with the increase of soil depth, nitrate nitrogen content increases slowly, 50~60 cm soil layer is slightly reduced. WN with the increase of soil depth, soil NO 3-1-N content increased gradually, the most in the deep soil accumulation, with the risk of water leaching. CK to nitrogen model, the different soil fertility period the nitrate nitrogen content of the smal est, but also show the leaching trend downward.(5)Cotton under the overall total nitrogen uptake of variable rate fertilization was significantly greater than the differential type fertilizer, nitrogen use efficiency and cotton production, the former is superior to the latter. Explanatory variable fertilization fertilizer effect is better than that of differential pressure type fertilizer.(6)Different fertilization pattern, N-W-N cotton uptake amount of N is higher than other fertilization mode; And N-W-N fertilization mode fluid medium total nitrogen content of plant total nitrogen proportion is the largest; N-W-N fertilization model seed cotton yield is higher than other fertilization model, and the difference is obvious. That N-W-N fertilization model can by increasing cotton nitrogen uptake and regulation of nitrogen in transgenic cottons migration al ocation to improve nitrogen use efficiency, realize the cotton production.(7)Think of soil water, nitrogen and production factors, the fertilization patterns of pre-nitrogen, then irrigation water in the middle, last nitrogen fertilizer(N-W-N) under uniform fertilizer fertilization way should be recommended.