Study On Soil Water And Nutrient Distribution Patterns Under The Integration Of Drip Irrigation And Fertilization

The application of drip irrigation under mulch can improve the utilization efficiency of water and fertilizer,it is a kind of irrigation technique with better water-saving fertilizer,belongs to local irrigation,it has the advantages of changing soil fertilizer and promoting incomes,and has been applied to production practice.Many factors influence the fertilization of drip irrigation under mulch,and the distribution of water and fertilizer in soil after drip irrigation under mulch has important influence on the optimization parameters of the drip system.Therefore,it is necessary to study the migration distribution of soil and water after drip irrigation under different conditions under mulch,so as to select a better model of drip irrigation under mulch,and provide guidance for actual production.In this paper,the change of soil water and fertilizer over time and the redistribution of water-fertilizer after drip irrigation and the migration and transformation of urea nitrogen in soil were studied in three kinds of drip flow(2,3,4l/h)and two kinds of fertilization methods by the infiltration experiments of soil column by drip irrigation under mulch.and using Hydrus software to simulate the process of soil water content and urea nitrogen migration in soil under the condition of irrigation and fertilization under mulch.The main research contents and conclusions are as follows:1)The film drip irrigation process,different flow,under the condition of fertilization,soil moisture content and EC changed with time,the soil EC increased rapidly with the increase of soil moisture content,and then decreased immediately and stabilized.Under the same fertilization method,the higher the flow rate of water,the higher the soil moisture content in the same position(the same distance from the drop head and the vertical distance);The same flow rate,the same time the same position of the soil moisture content is: water-fertilizer solution> water > uniform applicator.The difference of soil EC between different fertilization methods at different points of the same flow was different,and the change of soil EC showed that the conductivity was higher than that of water in the fertilization condition.Under the condition of drip irrigation and water,the higher the flow rate of the drop head,the greater the soil conductivity.Under the condition of applicator,the difference of soil EC between different flow rate is not obvious after the soil EC tends to stabilize.2)The soil moisture content in the soil profile decreases with the increase of distance from the drop head when the drip irrigation ends.Under different fertilization methods,the soil EC of water and fertilizer solution in moist body was larger.Flow rate is 3 and 4l/h,the distribution of soil EC is different under different fertilization methods,the flow rate is 2l/h,and the distribution law of soil EC is similar under different fertilization methods.The distribution of soil EC in different flow rate is different with the same fertilization method.After redistribution,the soil water content distribution tends to be the same in the soil profile,and the soil EC tends to stabilize.Under different flow rate,the soil EC of water and fertilizer is increasing with the passage of time,the soil EC of applicator and water is basically unchanged.3)The soil ammonium nitrogen mass fraction decreased with time and the soil nitrate nitrogen content gradually increased with the different drip irrigation and flow rate.Under the condition of drip irrigation and fertilization,the flow rate had effect on the content of ammonium nitrogen in 72 h under the drip fertiliztion.Drip irrigation applicator and fertilization the mass fraction of ammonium nitrogen in the soil decreased with the increase of the distance from the drop head in both horizontal and vertical direction.At the end of drip irrigation,the content of ammonium nitrogen in soil was almost unchanged with the increase of the distance between the applicator and the water and fertilizer solution in 120 h.The distribution of nitrate-n mass fraction in soil under different flow rate was not significant,and the soil nitrate-n mass fraction of drip irrigation and fertilizer solution was larger than that of applicator,and the distribution of nitrate in soil was affected by fertilization.4)Using Hydrus software to simulate the law of soil water and nitrogen migration under the condition of drip irrigation and fertilization under mulch.The fitting values of soil moisture content,ammonium nitrogen and nitrate nitrogen were 0.922,0.851 and 0.7 R2 respectively.Soil moisture content,ammonium nitrogen simulation value is matched measured value,reaction to its migration law,and soil nitrate nitrogen anastomosis effect is poor,different observation points,different time water content,ammonium nitrogen,nitrate nitrogen error are different.The relative error of soil moisture content is less than 10%,the variation range of mean square root error is 0.03~0.12,the variation range of soil ammonium nitrogen and nitrate n mean root error is 0.01~0.1 and 0.03~0.77 respectively.At the same time,on the basis of the validated model,the soil water and nitrogen migration law of three different fertilizer concentrations was simulated,the results showed that the higher the concentration of fertilizer liquid in the vicinity of 15 cm,the higher the content of ammonium nitrogen in soil,the more the soil nitrate-n mass fraction increased with the time,and the value near the drop head was larger,The concentration of manure had no effect on the distribution of soil water content.