| The Yellow River irrigation district of Inner Mongolia hetao is an important agricultural production areas in the north of our country. In the planting industry constantly in the development process of agricultural production use of chemical fertilizers and pesticides usage is more and more of the trend, and farmland drainage of N, P has the net loss of water environment load. In the process of the development of the planting industry constantly, agricultural production use of chemical fertilizers and pesticides usage is more and more of the trend, and farmland drainage of N, P has the net loss of water environment load. According to statistics, irrigation area every year in crops in farmers with spreading of pesticides has reached more than400tons, the chemical fertilizers and pesticides in addition to be part of the crops absorption, and the rest are in irrigation, with water when it rains back into drained in the ditch at all levels, and finally into the LiangSuHai. To reduce the drain the pollutant content farms and control of the loop irrigation water pollution, has become the hetao irrigation problems to solve a problem.This study based on the basic of farmland irrigation hetao yellow production status, in view of the Inner Mongolia hetao irrigation wheat sunflower interplanting, explore farmland back in the process of water transfer characteristics of nitrogen and phosphorus, and reveals the different level of fertilizer in the soil nutrient content under the action of water changes relationship, study N, P in irrigation leaching after water and soil in different depth in the distribution of the content. Mastering farmland during dewatering N, P in space migration rule, for making the non-point source pollution effective prevention and control measures to provide theoretical and practical basis.The paper main results are as follows:1. Through the field experiment sampling and analysis in the process of farmland water out different depth of soil nitrogen, phosphorus changes with time rule and nitrogen and phosphorus in different periods with the change rule of soil depth. Through the indoor soil column experiment, the simulation field0-200cm in different soil depth nitrogen, phosphorus changes with time rule and different period of nitrogen, phosphorus with depth change rule. Through the HYDRUS-1D model simulation to soil NO3--N and soil moisture content over time change is migration N the good agreement fitting results, application HYDRUS-1D model to simulate the process of farmland back N、 P migration is reasonable and credible.2. The test of different processing in residential water inside quit working process of leaching water collecting. analyzing different period leaching of water, TN、 TP、 NH4+-N、 NO3--N with depth change rule, sunflower with wheat in to deal with different between the change tendency of the same. Study of different treatment of district0～40cm、40-80cm、80-120cm lateral seepage fluid TN, TP change with time and obtain that the N, P in the horizontal migration rule.3. Through the different water and nitrogen treatment, analysis in the optimization of nitrogen and irrigation with, wheat and the highest yield sunflower. In the local conventional water and nitrogen based on section of water-saving nitrogen20%each, wheat yield can be increased by19.5%～31.85%, respectively, sunflower yield can be increased16.37%-18.44%, explain in a certain range of nitrogen, reasonable nitrogen can make wheat and sunflower production to increase effects, and the excess nitrogen against wheat and sunflower instead increasing output.4. Crop of sunflower nitrogen, phosphorus utilization research, showed that under local conventional irrigation nitrogen based on the day after the water saving20%nitrogen, N the utilization rate of the increased by36.15%, the utilization rate of fat to P, conventional water treatment and water saving section nitrogen fertilizer processing basic same, after20%water will not affect crops for the fat and the utilization of the P.In the section of20%based on conventional nitrogen fertilization,the nitrogen loss in the2m below the surface in soil was significantly less than conventional fertilization treatment.5. Simulation of the TN density through the soil leakage water boundary200cm of sunflower and wheat planting area of different N application mode using HYDRUS-1D model.On different N application mode of N in deep soil loss prediction, combination of N fertilizer on the effect of wheat and sunflower yield analysis,finally draws that the best N application amount of wheat was173.73kg/hm2and the best N application amount of sunflower was104.88kg/hm2. |
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