Effects Of Different Land Use On Soil Water Infiltration In The Semi-arid Loess Plateau

The local agriculture type is rainfed agriculture in Loess Plateau Semi-arid area for not only the landforms there are full of criss-cross ravines and gullies but also the groundwater table is deep,and the rainfall is limited.Water shortage is the main factor limiting the productivity of farmland in semiarid area of Loess Plateau.After a large number of experiments and years of researches,it shows that the most suitable land use is animal husbandry or the combination of farming and animal husbandry.Alfalfa has been one of the traditional forage crops in the area,however,the results have shown that there are differences in soil porosity,bulk density,soil saturated hydraulic conductivity between land covering with alfalfa and land covering with traditional crops.What,s more,due to the different intensity and soil depth of water consumption,the soil moisture of the soil profile have been different,which will affect the rainfall infiltration into the soil,which will,in turn,affect the water absorption and utilization of plants.Therefore,the objectives of this study were :(1)to figure out soil water deficit in the three land use types;(2)to study the effects of the three land use types on soil physical properties(including bulk density,soil porosity,saturated hydraulic conductivity and soil water characteristic curve);(3)to evaluate the soil water recharge in the experimental plot after receiving the application of 350 mm of water;(4)to discuss what caused the differences of soil water infiltration recharge in the three land use types.In our study,the change of soil water content and water storage were measured after giving the experimental plot 350 mm of water,and dye tracer was used to show the soil water flow in soil vertical profile,and VG model was used to fit soil moisture characteristic curve by MATLAB,and root system was collected by digging,and scanned and analyzed by EPSON V800 and WINRHIZO.The results showed that : 1)soil moisture deficit was the most critical in alfalfa land,and more critical in corn land compared to abandoned land;2)there were significant differences in saturated hydraulic conductivity,soil porosity and soil bulk density among alfalfa land and corn land and abandoned land;3)After receiving the application of 350 mm of water,it showed that the best effect on infiltration(from the aspects of the depth of infiltration into soil and water supplement amount)appeared in corn land,and then followed by abandoned land;4)Further analysis Indicated that there were two reasons which caused the differences of infiltration among the three land use types.One reason was soil preferential flow caused by root,the other reason was the soil water content of the land before receieving water.