Numerical Simulation And Experimental Study On Soil Infiltration Of Subsoiling

The tine spacings and tillage depths are the main factors affecting the effect of subsoiling,which have a direct impact on the process of soil-water infiltration.In order to solve the problem of soil-water infiltration and its redistribution under different tine spacings and tillage depths,this study prehensively applied a combination of discrete element simulation,Hydrus2 D numerical simulation and field experiment.The effects of tine spacings and tillage depth on soil-water infiltration characteristics were clarified.The effects of interaction between different tine spacings and tillage depths on soil-water infiltration,redistribution and evaporation under natural rainfall conditions were analyzed.It provides a basis for the selection of subsoiler operating parameters and the improvement of water use efficiency.(1)Numerical simulation of water infiltration in subsoiling based on EDEM-Hydrus2 D.Taking the arrow subsoiler as the object,the discrete element method,Hydrus2 D model and field experiment were used to simulate the soil-water infiltration process under different tine spacings and tillage depths.The results showed that: 1)there was a significant correlation between soil water infiltration characteristics and soil disturbance area under different cutting distances and tillage conditions;2)the tine spacings and tillage depths have a significant effect on soil-water infiltration characteristics,and the impact of depth is greater than the tine spacing.Increasing the tine spacing can increase the soil infiltration rate and reduce the vertical infiltration distance,which is beneficial to reduce the leakage loss of the cultivated layer;3)the position of soil water enrichment area moves down as the depth increases,and moves up as the tine spacings increases;4)The discrete element simulation is basically consistent with the shape of the soil disturbance profile obtained by the experiment.The simulated value of the soil volumetric water content of the Hrdrus2 D model is well fitted to the experimental value.Based on the combination of EDEM-Hydrus2 D,it can be used to study the soil water infiltration process under different tine spacings and tillage depths conditions.(2)The structure of furrow loose and ridge compaction soil has an important influence on the process of water infiltration and redistribution under natural rainfall conditions.Through the field planting experiment,the influence of the interaction between tine spacings and tillage depths on the vertical variation of soil moisture,profile water content and water storage were discussed.The experiment results showed that: 1)after the rainfall,the soilmoisture in the all loose area and the up loose and down compaction area is in the process of dynamic balance.Time reached equilibrium decreases as the ratio of soil loose to compaction increases.When the soil ratio of loose and compaction area is 5(the tine spacing is 40 cm and tillage depth is 35cm),the soil moisture coefficient of variation is the largest and the infiltration is the fastest;2)the effect of loose and compaction soil structure on the water storage capacity is within the range of 0~40cm soil layer,and the water holding capacity of the up loose and down compaction area is greater than the all loose area.When the soil ratio of loose and compaction area is 6.5,the soil water storage increases the most,when it is 5,the increment is the smallest.(3)The effect of furrow loose and ridge compaction structure is conducive to the maintenance of soil moisture.Through field evaporation experiments,the effects of tine spacings and tillage depths on evaporation and crop transpiration were discussed.The results showed that: 1)the loose and compaction plough layer structure formed by subsoiling changed the process of soil-water migration;2)during the growth period of summer corn,the water consumption in the up loose and down compaction area was greater than that in the all loose area,and both were lower than no-till treatment;3)the evaporation intensity decreased first and then increased during the growth period.The evaporation intensity between the soils in the up loose and down compaction areas was 1.53~1.75 times higher than that in the all loose area.When the soil ratio of loose and compaction area is 6.5,the total evaporation is the lowest,and the crop transpiration accounts for 68.33% of the total evaporation,which is conducive to the improvement of soil moisture retention and utilization.