Effects of Fertilization on the Properties of Soil Water Supply in Dryland

The abilities of soil water supply of different soil layers in soil profile in Weibei loess plateau of Shaanxi Province are different and represent a distribution. with fertilization they show a low-high-low-high form, with CK treatment they show a high-low-high-low form when soil water content is less than 12.5% and a low-high-low-high form when soil water content is more than 12.5%. There is a soil layer where soil water potential is lowest in the soil profile and this layer goes down with the increase of fertilization,which may has an important effect on limited water use. This is due to the wave distribution of soil water potential in different soil layers of soil profile. Fertilization can raise soil water potential and reduce water capacity and thus increase the ability of soil water supply, and hence improve the adaptation and resistance of soil to drought. The specific water capacity of soil reflects the properties of soil water retention,soil water potential and water capacity reflect the properties of soil water supply, i.e. availability of soil water to plants.