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Effect Of Sand Allocation On Macropores And Saturated Hydraulic Conductivity Of Clay Saline Soil

Posted on:2022-12-03Degree:MasterType:Thesis
Country:ChinaCandidate:S X DaiFull Text:PDF
GTID:2480306749999189Subject:Agronomy
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In this study,aiming at the problems of poor soil porosity,low soil saturated hydraulic conductivity and difficult treatment of sediment deposition in the Yellow River irrigation area in coastal clay saline soil,the sediment deposition in the Yellow River irrigation area was used as an improved material to study the influence of sand allocation on the macropores and saturated hydraulic conductivity of clay saline soil.Through indoor soil sediment particle analysis test,water characteristic curve test,saturated hydraulic conductivity test and simulated soil column salt leaching test,the relationship between soil particle composition change and soil fractal dimension,soil macropore ratio,soil saturated hydraulic conductivity and desalination efficiency was studied,and verified by field experiment.The main results of this study are as follows:(1)The difference of particle composition between yellow sediment and clay saline soil is obvious.Adding yellow sediment into clay saline soil can effectively reduce the clay content of clay saline soil,increase the content of fine sand,and then affect the fractal dimension of clay saline soil.Soil fractal dimension was significantly positively correlated with clay content,and significantly negatively correlated with extremely fine sand content.(2)With the increase of sand distribution,the proportion of large pores in clay saline soil increased linearly,and the saturated hydraulic conductivity increased exponentially.The clay content in soil was significantly negatively correlated with soil macropores and saturated hydraulic conductivity,and the extremely fine sand content was significantly positively correlated with soil macropores and saturated hydraulic conductivity.Soil fractal dimension is significantly correlated with soil porosity and saturated hydraulic conductivity.The accuracy of soil fractal dimension in estimating soil porosity and saturated hydraulic conductivity is higher than that of clay and fine sand.(3)The relationship between soil saturated hydraulic conductivity and soil macropore ratio is exponential function,and the relationship between soil desalination efficiency and soil saturated hydraulic conductivity is power function.Adding yellow sediment can improve the proportion of large pores in clay saline soil,increase the saturated hydraulic conductivity of soil,significantly improve the efficiency of soil desalination,and accelerate the leaching of salt in soil.(4)Adding yellow sediment can effectively change the particle composition of field treatment.With the increase of sediment distribution,the clay content of field treatment decreases gradually,and the content of fine sand increases gradually.The regression equation of indoor simulation test was verified by field data.The results showed that the fractal dimension predicted by clay content,the proportion of soil macropores predicted by fractal dimension and the saturated hydraulic conductivity predicted by fractal dimension were more accurate.(5)Adding yellow sediment into the 0-20cm soil layer of clay saline soil can effectively reduce the soil salt content of wheat root activity layer(0-40cm)in clay saline soil,improve soil water mobility and accelerate soil salt leaching.The three-year yield of wheat in the field showed that the addition of yellow sediment could effectively improve the yield of wheat in clay saline soil,and the wheat yields of 10kg/m~2 and 15kg/m~2 treatments increased most significantly.
Keywords/Search Tags:Yellow water sediment, Clayey saline soil, Soil fractal dimension, Soil macropores, Soil saturated hydraulic conductivity
PDF Full Text Request
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