Effects Of Different Straw Mulching Amount And Burial Depth On Soil Water And Nitrogen Transport

In order to explore the influence of different straw mulching amount and straw burial depth on soil water and nitrogen transport,using urea,black soil and corn stalks as test materials,based on the indoor soil column test,3 fertilization levels(N1,N2,N3)were set,3 One mulching level(S1,S2,S3)and three burial depth levels(M1,M2,M3),using a combination of theoretical analysis and model simulation to clarify the one-dimensional vertical soil under different straw mulching amounts and straw burial depths Infiltration characteristics,soil water redistribution and soil nitrogen migration and distribution law,through theoretical analysis and model construction,the soil moisture distribution and nitrogen transport law were studied,and the effects of different straw mulching amounts and straw burial depths were comprehensiv ely compared and analyzed.Based on the differences in the impact of soil water and nitrogen transport,the optimal straw mulching amount and optimal burial depth are proposed,which provide references and basis for the popularization and application of straw mulching technology and the efficient use of soil water and nitrogen.The main conclusions drawn are as follows:(1)Under different straw coverage,the Kostiakov model can better fit the soil infiltration process;except for the N2S1 treatment,the wet front migration distance of the other treatments is reduced compared with the control.With the increase of straw coverage,the change of the wet front does not appear Obvious law: Except for N3S1 and N3S2 treatments,the cumulative infiltration rate and average infiltration rate of the other treatments are greater than those of the control.Compared with the control,the influence of straw coverage on the cumulative infiltration rate and average infiltration rate does not show a significant change trend.;Straw mulch can significantly increase the soil moisture content,and the greater the amount of straw mulch,the more obvious the improvement of the soil moisture content,the 150% straw mulch increased by4.15%;compared with the soil moisture content before the redistribution of soil water,the straw mulch The higher the soil moisture is redistributed,the smaller the drop of soil moisture content will be.(2)The Kostiakov model can be used to fit the soil infiltration process under the condition of straw burial depth;the wet front,cumulative infiltration amount and average infiltration rate under different straw burial depth treatments all increase with the increase in burial depth;except for N1M3 and N3M2,the rest The treated soil moisture conten t decreases with the increase of burying depth;compared with the soil moisture content before soil water redistribution,the straw burying depth is 10 cm,after the soil moisture is redistributed,the soil moisture content below the straw burial depth decreases,and the straw burying depth is 20 cm With the treatment of 40 cm,the soil moisture content in the soil layer below the straw depth increases after the soil moisture is redistributed,and the increase increases with the increase of the straw depth.(3)Under different fertilization rates and the same amount of straw mulching,the relationship between fertilization rate and wetting front is not significant,and the cumulative infiltration rate and average infiltration rate decrease with the increase of fertilization rate;under the same burying depth,with the increase of fertilization rate,the wetting front is not obvious According to the law of change,the cumulative infiltration rate and the average infiltration rate gradually increase;the Kostiakov model is effective in fitting the soil infiltration process under different fertilization rates;the soil moisture content is significantly increased under different fertilization rates.After the soil moisture is redistributed,Under the same straw mulc hing amount,the soil moisture content does not show an obvious law with the increase of fertilization amount.Under the same burying depth,the soil moisture content first increases and then decreases with the increase of fertilization amount,and the soil moisture content of 150% fertilization amount decreases compared with that before water redistribution.The amplitude is the smallest.(4)Under different straw mulching conditions,before soil moisture is redistributed,the soil nitrate nitrogen and ammonium nitrogen content decrease with the increase of soil depth,and the greater the amount of straw mulch,the higher the soil nitrate nitrogen and ammonium nitrogen content;After the water is redistributed,compared with before the soil water is redist ributed,as the soil depth increases,the nitrate nitrogen content first decreases and then increases,and the ammonium nitrogen content gradually decreases;the nitrate nitrogen and ammonium nitrogen content in the leaching solution Under different leaching times,there was a trend of first increasing and then decreasing,and the greater the straw coverage,the more obvious the increase of nitrogen concentration in the leaching solution.(5)In the process of straw burying depth,as the depth of the soil layer increases,the soil nitrate nitrogen and ammonium nitrogen content gradually decrease,and the soil nitrate nitrogen and ammonium nitrogen content at the depth of the straw burial significantly increase;the straw burying depth is lower than the soil layer The soil nitrogen content is higher than the soil layer below the straw burial depth,and the soil nitrogen content decreases with the increase of the straw burial depth;after the soil water is redistributed,the nitrate nitrogen will accumulate in the straw burial depth,which is compared with before the soil water redistribution,The soil nitrate nitrogen content decreases first and then increases with the increase of soil depth.The nitrogen content at the depth of straw burial is higher than that at the corresponding position without straw burial treatment;compared with the soil moisture before redistribution,the burial depth of straw is 10 cm Treatment,the soil nitrate nitrogen content of the soil layer below the straw burial depth decreased,and the soil nitrate nitrogen content of the soil layer below the straw burial depth increased with the straw burial depth of 20 cm and 40 cm.The ammonium nitrogen content of different straw burial depths increased with the depth of the soil layer.The inc rease gradually decreases;the content of nitrate nitrogen and ammonium nitrogen in the leaching solution increases first and then decreases with the increase of leaching times.The burying of straw in the soil layer will inhibit the migration of nitrogen.(6)Different fertilization rates have significant effects on soil nitrate nitrogen and ammonium nitrogen content,and the larger the fertilization amount,the higher the soil nitrogen content;the soil nitrogen content gradually decreases with the increa se of soil depth before soil water redistribution,which is relative to the soil Before the water redistribution,after the soil water is redistributed,the soil nitrate nitrogen content of 0-40 cm soil layer appears to decrease,and the decrease range is between 1.53%-7.31%,and the soil nitrate nitrogen content of 40-60 cm soil layer appears to increase,The increase range is between 1.10%-15.89%,and the content of ammonium nitrogen in different soil layers shows a decrease.(7)The machine learning algorithm is used to construct a linear model of soil nitrate nitrogen and ammonium nitrogen content and soil depth under the conditions of different straw coverage,different straw burial depths and different fertilization rates.The model has high accuracy an d can be used in different depths of soil Estimation of nitrate nitrogen and ammonium nitrogen content.