Research On Transformation Test Of Nitrogen In Field Soil Under The Conditions Of Controlled-Drainage

Fields drainage is the important measure that is adjustment of agricultural land water level and control of soil moisture contents. This study based on the natural conditions and cultivation characteristic of south China, the experiment based on the soil column experiment, simulating no crops growing. To explore the impact to the nitrogen losses and distribution in soil profile of various drainage time and various displacements. Devise stalks were intercepted in the field nitrogen. Devise the role to nitrogen tackling of straw mulching. And using one-dimensional soil quality moving model to simulate and forecast the laws of distribution and moving of nitrogen in the soil. The main results are as follows:(1)Preliminary test results show that different experimental treatments on the loss of water from the stream to intercept effects are good. Carved into the testing process two different amounts of nitrogen fertilizer applied to deal with soil columns under low fertilizer better than some of the interception,the loss of ammonium through the drainage and nitrogen fertilization treatment were lower than the high of8%to9%and8%to15%.(2) Drainage time on the initial nitrogen concentration in subsurface drainage no significant effect on the handling of its smaller displacement interception of nitrogen is better than the displacement of a larger deal.On the conditions that there is no straw mulching, the concentration of reveal states nitrogen and nitric oxide states in drainage are obviously higher than the soil column that there is straw mulching. It proved that straw mulching has a positive role of reducing the loss of nitrogen, improving the environment of the field. To reduce pollution from the perspective that the use of straw treatment began after fertilization4d drainage, displacement of2mm/d for the optimal handling of treatment.(3) Dealings with different drainage time and displacement, the nitrogen density change in the law along with the depth is:the nitric oxide and total nitrogen concentration increased with soil depth is reduced during the test was20cm at the nitrate concentration, indicating that straw help to promote gentrification. And the reveal states nitrogen reduces first along with the depth increase, and achieves the minimum value in about50cm place, and then significantly increase in the drainage.(4) Establishment of one-dimensional mathematical model of solute transport in soil, and using Hydrus-1D model, started two days after fertilization drainage, displacement of4mm/d of processing in the jointing stage of nitrate in the soil after fertilizer distribution simulation, simulation results Experimental measured value has some error, error in6%, the trend is more consistent. This model can be applied to simulation and prediction of nitrogen movement.This research can deepen the drainage condition of soil nitrogen transport and transformation of understanding for the environmental management of farmland drainage and provide a scientific basis.