Study On Water And Nitrogen Migration Of Point Source Infiltration Under Variable Concentration

The local infiltration irrigation under the point source infiltration is the prominent feature of drip irrigation and membrane irrigation.At present,there are few studies on the law of point source infiltration,and the research on the concentration change is less.This paper focuses on the point source drip irrigation infiltration conditions of water and nitrogen concentration decay migration research,through the soil bin test a comparative analysis of the differences and changes under the conditions of concentration of fixed point source into the migration law of nitrogen water seepage,explore the conditions of water and fertilizer solution concentration decay point source infiltration mechanism,draws the following conclusion:1.The radial wetting distance and vertical wetting distance of drip irrigation point under the condition of fixed concentration and concentration decay were all increased with the increase of irrigation duration.When the soil bulk density was 1.35g/cm³,the radial velocity of water was faster.Radial infiltration distance and vertical wetting distance and fertilizer concentration and fertilizer solution concentration decay rate has little relationship;the radial and vertical wetted distance with irrigation time increased as a power function,exponential difference is small,the average values were0.34 and 0.43;fixed concentration and concentration of different attenuation distance and vertical radial distance between the wetting rate to conform to good parabola relationship.2.The distribution of soil moisture content under different fixed rate and concentration at different decay rates,the initial concentration of different fertilizers,and the decreasing rate of soil moisture decreased with the increase of radial and vertical wetting distance,The same distance from the point source,the soil moisture content difference is also very small,the concentration of attenuation makes the difference from the fixed concentration of 3%to reduce the concentration of less than 1%.Whether the concentration of fertilizer was attenuated and the rate of decay has no significant effect on the distribution of soil moisture content under the condition of drip irrigation on the whole.3.The distribution of NO₃-N in the wetted body under the fixed concentration and concentration decay condition?the ratio of soil nitrate N concentration and the initial nitrate nitrogen concentration C₀at the end of irrigation?shows that the attenuation of nitrate nitrogen concentration and not wet inside soil were less than the initial soil nitrate content value.The content of nitrate nitrogen accumulated in the wetted body at the edge of humid produce.4.The initial concentration of nitrate nitrogen in the solution tank was 300,and 900mg/L at the decay time of 50min and 20min respectively,and the concentration of nitrate in the solution?the real-time concentration of nutrient solution used for drip infusion?showed a good exponential decay with time,and the exponential relationship accorded with y=a?R²>0.98?.The average concentration of NO₃-N in the interior and the edge of the wetted body was determined by the fixed concentration and the concentration at different decay rates were analyzed.The results showed that the internal concentration of the wetted body?radial distance dropper 15cm and vertical dropping tip 10cm?When the initial concentration of the solution is the same,the content of nitrate nitrogen in the moisturizing body is not very different in space,and it increases at the edge of the wetted body.It has no obvious relationship with the initial concentration of the fertilizer.The faster the attenuation rate,internal nitrate wetted body average concentration is higher,but the nitrate concentration at the edge of wetted body due to attenuation of different amount of fertilizer is small?the actual amount of fertilizer was 1.2 g?,nitrate nitrogen concentration at the edge of wetting body average with concentration and attenuation the decay rate increases,but the initial concentration of nitrate nitrogen concentration is higher,the average edge wetted with concentration attenuation and attenuation rate did not change significantly increased.