| In order to study Contour Reverse-slope Terrace(In 2009,setted)under the order processing measures,different soil slope(0~10 cm,10~20 cm,20~40 cm,40~60 cm,60~80 cm,80~100 cm)spatial distribution of soil saturated hydraulic conductivity and its influence factors,such as the Contour Reverse-slope Terrace effect on the improvement of the soil water holding capacity,soil water drive characteristic and water conservation capacity.The small watershed of Yi Songhuaba Dam in Kunming northern suburb of central Yunnan was selected as a research area in this study.Stratification of 0~100cm soil,by means of field monitoring and indoor test analysis,compared the soil saturation water conductivity of Contour Reverse-slope Terrace treatment with the undisturbed slope farmland,the soil physical characters and soil moisture characteristic curves of the 0~100cm range of the downhill cultivated land under the condition of Contour Reverse-slope Terrace were determined.The parameters of Van Gennuchten model were obtained by fitting the vanFit software,elucidated the water retention of soil in each soil layer and its relationship with the influencing factors,the spatial and temporal variation characteristics of soil water storage at different soil depth(0~100 cm)from May 1st,2017 to April 30th,2018 and their relationship with other physical properties were analyzed.The results showed that:(1)After laying Contour Reverse-slope Terrace,the powder content of each soil layer of slope cultivated land increased,the soil bulk weight decreased,the soil moisture content increased,and the soil saturated water conductivity increased significantly.The content of silt in each soil layer increases by 7.6%?18.6%?22.7%?20.2%?12.9%and 1.7%respectively;except the surface soil,the bulk density of each soil layer decreased by 5.6%?12.1%?5.8%?4.1%and 6.7%,respectively;the soil moisture content of each soil layer increased by 17.3%?14.6%?29.4%?18.6%?29.9%and 31.7%,respectively;the average saturated water conductivity was about 4 times times that of the original slope;with the increased of soil depth,the saturated water conductivity of soil tended to increase first and then decrease.The direct path coefficient of soil bulk density was-0.371,the direct negative effect on Ks was the strongest,the direct path coefficient of the particle content was 0.398,the direct positive effects on Ks were strongest.(2)The effect of Contour Reverse-slope Terrace on soil moisture constant was not significant in the upper slope(p>0.05),significant in the inverse slope(p<0.05),and was very significant in the lower order slope(p<0.01).In relation to the parameters of soil water characteristic curve,the content of bulk density and sand grains were negatively correlated,and total porosity,capillary porosity and particle content were positively correlated.The determining coefficients of the model fit soil moisture characteristic curve were higher than 0.85,and the R~2 was higher reliability.The n values of the undisturbed slope cultivated land(1.7196)and the Contour Reverse-slope Terrace treatment slope cultivated land(1.7735)were the largest in the 10~20 cm soil layer.The change of soil moisture content in sloping farmland with Contour Reverse-slope Terrace was greater than that of intact sloping farmland.The slope farmland of the original sloping farmland and the Contour Reverse-slope Terrace treatment slope cultivated land was good in 10~20 cm soil,and the slope farmland with Contour Reverse-slope Terrace was strong in 40~60 cm soil,and the undisturbed sloping farmland had strong water holding capacity in the 20~40 cm soil.(3)After laying Contour Reverse-slope Terrace,the average soil water storage of each soil layer increased significantly,and the coefficient of variation of soil water storage decreased significantly(p<0.05),but with the increase of soil depth,the soil water storage capacity decreased obviously.During the rainy and dry seasons,the average soil water storage in each soil layer increased by 9.6%~13.5%per cent and10.0%~23.9%per cent,respectively.With the increase of soil depth,and the amount of soil water storage decreased significantly,and the order of impact on soil water storage in each soil layer was shown as 40 cm>20 cm>60 cm>80 cm>100 cm.The correlation analysis between soil physical properties and soil water storage under the Contour Reverse-slope Terrace showed that the effect of the interaction of Contour Reverse-slope Terrace treatment and different soil depths on soil water storage was significant,and the sum of squares of the modified model reached 48149.124.In conclusion,the Contour Reverse-slope Terrace treatment had obvious effect on the increase of saturated water conductivity of sloping farmland,and had obvious improvement effect on the water retention performance of sloping farmland soil and the water storage capacity of sloping farmland soil,which had a significant impact on increasing soil water infiltration and reducing soil erosion in sloping farmland. |
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