Through the experiment of different Irrigation Amounts with urea applied, the paper studied the influence of Irrigation Amounts on soil nitric nitrogen dynamical changes under film hole irrigation and the nitric nitrogen content of the growing period was determined. The result showed: different irrigation amount in the profiles being 3cm and 8cm away from the film hole center, it appeared nitric nitrogen accumulation peaks, increased the irrigation amount promoted the transformation of urea, increased the transformed nitric nitrogen content and distribution of nitric nitrate and the risk of nitric nitrate leaching. In the profiles being 3cm away from the film hole center, the nitric nitrogen accumulation peak significantly reduced at harvest stage, but it reduced in the profiles being 8cm away from the film hole center at milky stage. The milky stage was the maximum period when the corn uptook nitrogen at different irrigation amount. Increased irrigation amount lower the accumulation content of nitric nitrogen near the film hole center after harvest, and higher the accumulation content of nitric nitrogen far away from the film hole center. Above researches could provide the basis for rational fertilization of farmland and nitrate environmental impacts on assessment.
The method of measuring saturated soil hydraulic conductivity by using permeating bucket is easy and simple and the instrument is cheap. The water volume must be measuring for many times, meanwhile the water must be added on the top of permeating bucket to sustain the water layer thickness. Based on the principles of supplying water in the fixed water head by Marriott bottle, the method mentioned above is improved, which can reduce the experiment work and improve the experiment accuracy.
The effect of initial water content on water transport characteristics in injection irrigation is analyzed through an indoor experiment of injection irrigation in different initial water contents. The research shows the following results. The relationship between the cumulative infiltration and time accords with power function. The higher the initial water content is, the bigger the cumulative infiltration is in the same time. The wetting front is a semi-circle with its center below the water outlet, the transport velocity of which slows down with the passing of time. The transport velocity of vertical section crossing the middle of the two outlets approaches that of vertical section at the middle point of the central line of the two outlets. The higher the initial water content is, the shorter the time of the transport velocity of the two sections similar to each other is. The water wetted range is comparatively wider, and the water content is comparatively higher below the outlet, and it is reverse above the outlet. The higher the initial water content is, the wider the wetted range is and the higher the water content of the soil being the same distance from the outlet is. The above research provides a basis for supplementing the theories and technologies of injection irrigation.
Through the facilities imitating experiment of film hole irrigation with nitric acid potassium solution under different film hole diameter, the content of soil water and nitric nitrogen was determined and analyzed in the different time after irrigation. The result shows: the content of soil water and nitric nitrogen under different film hole diameter reduced with time and achieved the maximum at the center while it is reverse away from film hole; soil water content decreased with the increase of film hole diameter at the same position while the nitric nitrogen content was opposite. The influence of the increase of film hole diameter on soil water and nitric nitrogen distribution is harm for plant to absorb water and nitric nitrogen, so it will be better to reduce the film hole diameter in the agriculture production. The result provided the proof for the sustainable development of facilities agriculture and evaluating the effect of nitrogen on environment.
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