Distribution Of NO₃-N In The Soil Under Different Irrigation And Fertilization Conditions

[Object] With the wide popularity of the drip irrigation in XinJiang, most domestic andforeign scholars have made much research in total growth period of crop irrigation andfertilization, soil nitrogen transformation and distribution under the single irrigationfertilization are very scarce. The experiment for the specified field simulation of dripfertilization, to explore the effects of soil fertilizer drop after a long time the nitrateconcentration distribution under the different irrigation and fertilization conditions.Determination of water and nitrogen gradient suitable single irrigation and fertilizationvolume.In order to optimize the irrigation and fertilization in farmland and provide atheoretical basis to reduce nitrate leaching loss.[Methods]In the simulation under drip fertigation, set4irrigation methods:27（low）,54（normal irrigation）,81（high water）,108（high water） mm, expressed by W₁, W₂, W₃, W₄;and4irrigation methods:0（control）,52.5（conventional N）,105,157.5kg/hm²,expressed by N₀、N₁、N₂、N₃,The N0treatment only irrigation but no nitrogen application.[Results]（1）Under the condition of normal irrigation （54mm）, NO₃-N content distribution different inthe vertical0⁷0cm is significantly,content was reduced due to the increase of soil depth.Under the same nitrogen level, appears the trend from the soil surface to the deep graduallyreduced, there is no phenomenon on NO₃-N cumulative.When the N application rate reached52.5kg/hm², the concent of NO₃-N changes most gently, the distribution trend in horizontaland vertical was better than others,recommended for the best irrigation in the experiment.（2）Under the condition of normal fertilization（52.5kg/hm²）, different irrigation on NO₃-Ncontent distribution difference is significantly, the distribution of NO₃-N content in verticaland horizontal direction were different on the basis of high or low irrigation quota. Under theW₁（lower water） and W₂（normal water） treatment, NO₃-N content is inversely proportionalrelationship with the increase of soil depth,there is no serious cumulative infiltrationphenomenon in the deep soil layers.Under the W₃（high water） and W₄（ultra-high water）treatment,the NO₃-N content increased with the increase of soil depth, and NO₃-Naccumulated in the60⁷0cm soil layer, occured significant accumulate phenomenon in thedeep soil. The change in the soil is the most stable when under the W₂（54mm） treatment, NO₃-Nconcent decline rate is minimal between the different soil layer. In combination with fieldcrops root absorption and utilization of the fertilizer, recommend W₂（54mm） for the optimalirrigation.（3）Selected different kinds of combinations in this experiment，analysis of water content andthe distribution of NO₃-N content in the soil vertical0⁷0cm. Results show that under theW1N1and W2N1conditions, water content and the distribution of NO₃-N content showed good correlation, both of them are decrease with the increase of soil depth.But under high waterconditions,water content and the NO3-N content in contrary trend, NO3-N accumulating withsoil depth and the water content is reduced. In conclusion, inappropriate combination ofwater and nitrogen will directly affect the moisture and the distribution of NO3-N. Hinder thecrops the absorption of the fertilizer, even cause different degree of pollution of theenvironment.[Conclusion]The distribution of nitrate nitrogen in different soil profile affected by theamount of irrigation and nitrogen fertilizer significantly.Single irrigation volume reached81mm and108mm will cause the leaching loss of nitrate nitrogen in horizontal and verticaldirection. Effects of different nitrogen treatments on the nitrate distribution in the verticaldirection is more obvious. In this experiment, recommended for the nitrogen rate was52.5kg/hm², and the irrigation was54mm.