EFFECTS OF LAND USE ON SOIL MOISTURE VARIATIONS IN A SEMI-ARID CATCHMENT: IMPLICATIONS FOR LAND AND AGRICULTURAL WATER MANAGEMENT

Knowledge of the effects of land use on soil moisture variations is necessary to improve land and agricultural water management in the semi-arid Chinese Loess Plateau. However, previous studies are insufficient to guide management practice in this area and improvement is needed to help with the development of the 'Grain for Green' programme. As part of the 'Grain for Green' programme, we examined the effects of five land uses (fallow, grassland, cropland, 3-year and 8-year jujube orchards) on soil water variations in a small catchment on the Loess Plateau. Soil moisture at 0-160 cm depth was monitored approximately weekly at 47 sites from 17 August to 19 October 2009 and from 4 April to 27 September 2010 using a portable time domain reflectometer. Results indicated that mean soil water profiles in different land uses varied with time, land use induced spatial variations of soil water but exerted negligible influence on soil water temporal patterns, and soil water content was of the greatest spatial variability with moderate means (approximately 20 per cent). Furthermore, the relationship between standard deviation and mean water content was dependent on soil depth, although it was negligibly affected by land use. Profile soil water for five land uses was different in various seasons, precipitation infiltration depth exhibited a positive correlation with precipitation, and the whole profile soil moisture (0-160 cm) was complemented following a 93 center dot 5-mm rainfall event. The findings presented here provide helpful information for land and agricultural water management in this area. Copyright (c) 2011 John Wiley & Sons, Ltd.