Study On Soil Water Characteristics Of The Natural Restored Grassland In Semi-arid Hilly Loess Region In The Southern Ningxia

The soil water physical characteristics, deficit of the soil water content, and dynamics of the soil water content were studied during the vegetation restoration of the southern semi-arid region of loess Plateau in Ningxia , the results are as following:(1) There are obvious differences related to soil water physical properties of different vegetation types. The bulk densities of artificial grassland > that of nature grassland; Soil saturation supporting water capacity , soil field water capacity, soil capillary supporting water capacity of nature grassland > those of artificial grassland. The soil water physical properties have obviously profile vertical distribution law. In the range of 0-100cm soil layer, the changeable tendency of the bulk densities is increasing with deepening of soil depth, while that of Soil saturation supporting water capacity , soil field water capacity, soil capillary supporting water capacity is decreasing. The distribution law of the soil water physical properties along the slope side is obviously changeable. At the same slope degree and the same slope aspect, the changeable tendency of the bulk densities is increasing from bottom to top of the slope, while that of Soil saturation supporting water capacity , soil field water capacity, soil capillary supporting water capacity is decreasing.(2) In study on the redistribution of precipitation in the soil of the slope terrain: slope degree, slope aspect and slope position have obviously effects on the distribution of soil water content; the change of 0-100cm depth soil water content is that: at the same slope aspect, the smaller the slope degree is ,the smaller the soil water content is; Soil water content of semi-shady slope > that of semi-sunny slope; On the same slope face , soil water content of middle slope position > upside slope position, downside slope position.(3) The vegetation types and soil water content. In this experiment, the conclusion is that the soil water content of artificial grassland 16.1%, that of seabuckthorn forest 14.8%, that of nature grassland 14.5%. The soil water content of artificial grassland 16.1% , that of seabuckthorn forest 14.8% > that of nature grassland 14.5%.(4) The influence of artificial disturbance on redistribution of the soil water content: Different soil treatment has also a big effect on the distribution of soil water content. The soil water content of the treated soil type > that of non-treated soil type.(5) From study on the vertical change of soil water content: it are divided three layers :① soilwater easy change layer@soil water using layer ?soil water stable layer. For there is the different distribution of roots, the vertical change of soil water content of artificial and nature grassland is different.(6) From the studies on characteristics of 0-100cm soil water storage: it is concluded that soil saturation water storage of artificial grassland is higher than that of nature grassland, while the available soil water storage of nature grassland is higher than that of artificial grassland .The change of soil precipitation storage is similar with the change of the available soil water storage.(7) From the seasonal change of soil water storage ,the artificial and nature grassland are all experience three phrase :?spring and summer lose water period(4month~7monfh)?summer and fall increase water period(7month~9month)(3)fall lose water period (9month~10month)(8) In the soil depth of 0-100cm, there exist soil water deficits not only in artificial grassland but also in nature grassland .The deficit value of the nature grassland is larger than that of the artificial grassland. The deficit value of the artificial grassland is in the range -3.7—9.9; The deficit value of the nature grassland is in the range -11.3—13.6; there exist soil water deficit in different month(l-lOmonth) and different soil layers(l-lOOcm). And the change of the soil water deficit of the artificial grassland is different with the change of the nature grassland except in the soil layer 0-20cm in which the soil water deficit is always existing.