Abstract: By the method of cross correlation coefficient in geo-statistics, this paper studied the soil hydraulic properties and their influences on soil water distribution under four land uses, i.e., farmland, waste-grassland, forestland, and alfalfa land in Liudaogou watershed of Loess Plateau. The results showed that farmland soil and waste-grassland soil had the similar physical characteristics, as did forestland soil and alfalfa land soil. For any given soil suction, farmland soil had the highest water content, while forestland soil had the lowest one. The opposite was observed for the saturated hydraulic conductivity of soil water. In forestland and alfalfa land, soil water content increased with increasing depth during water consumption period, but decreased with soil depth at any other time. The influence range of saturated hydraulic conductivity on soil water content depended on soil water condition. During the compensation period of soil water, the influenced lag distance of saturated hydraulic conductivity to water content was 0-40 cm, and that of water content to saturated hydraulic conductivity was 0-50 cm; while during the stable period of soil water, the influenced lag distances of saturated hydraulic conductivity and water content were both 0-60 cm. There were positive correlations between the two properties under all land uses during these two periods. During water consumption period, saturated hydraulic conductivity was positively correlated with soil water content in farmland and waste-grassland. The influence range of saturated hydraulic conductivity to water content was about 0-80 cm, while that of water content to saturated hydraulic conductivity was 0-60 cm. However, negative correlation was observed in forestland and alfalfa land, and the influence ranges were also about 0-60 cm.

Key words: straw mulching, soil respiration, warming, film mulching