Seasonal Variation of Soil Water Content and Water Use Efficiency in the Water-Wind Erosion Crisscross Region of the Loess Plateau

By establishing the runoff plots of three vegetation we carried on the site-specific observation on the soil moisture in the water-wind erosion crisscross region on the Loess Plateau,and analyzed the effect on seasonal variation of soil moisture and water use efficiency.Results showed that soil temperature at 5 cm depth was significantly below air temperature during the growing season;seasonal fluctuations of soil surface moisture at 0-6 cm depth was influenced by the temporal pattern of rainfall.Vegetation had a significant impact on seasonal variation of soil deep moisture(p0.05).Soil moisture was consumed from May to July and compensated from August to October.Soil moisture from the soil surface to the vertical section increased firstly,then reduced,and increased again.Vegetation had different influence on soil moisture of the same terrain parts,and the soil moisture of the same vegetation at different terrain parts also had significant difference.Mung bean land runoff coefficient was 0.238,and it was significantly higher than abandoned land and alfalfa land.Hay yield and water use efficiency under vegetation significantly reached difference level(p0.05).Water use efficiency of alfalfa was 1.9 times more than that of mung bean and 8.3 times of mung bean kernel.Grain for green program significantly increased surface runoff infiltration and had good soil and water conservation effects.Meanwhile it improved water use efficiency of vegetation.