Abstract: In order to explore the water distribution characteristics of soil profiles in the cropping systems in the Hill and Gully Regions on the Loess Plateau, five land use categories were selected for study: Mulched corn field (YMD), fallow 2 years (XGA), fallow 4 years (XGB), waste grassland (HCD), and alfalfa field (MXD); and the soil moisture content was measured in various soil layers to 200 cm depth. It was found that, for the 0-20 cm soil depth at P<0.05, the soil moisture content of the five land use categories ranked YMD>XGA>XGB>HCD=MXD. Soil moisture content for the 0-20 cm soil depth in the YMD category was 20.28%, and exceeded that in categories XGA, XGB, HCD, MXD by factors of 1.38, 1.40, 1.94 and 2.91, respectively. With increase in soil depth, the soil moisture profile of YMD showed a ‘double-peak' pattern. Soil moisture content in HCD and MXD categories decreased with depth in the upper layers, to a value stable across the deeper layers. For XGA and XGB categories, the trend in soil moisture content with increasing depth was an initial increase, followed by a zone of decrease with depth, and then basically stable with increasing depth. Soil moisture spatial variability in all layers of XGA and MXD categories was moderate, and low in HCD. For YMD, soil moisture spatial variation was moderate, except for the soil layers 80-100 cm and 180-200 cm, which had low variation. For XGB, soil moisture contents of the 0-180 cm soil layers were moderately variable, but the soil moisture variation of the 180-200 cm soil layer was greater. Across the 200 cm soil depth surveyed, the average coefficient of variation for water content of the soil profile of the 0-200 cm layer was 40.75%, 38.02%, 30.91%, 27.06%, 4.12%, respectively, for XGB, XGA, MXD, YMD and HCD, land use categories. Soil water use in XGA and XGB land use categories was primarily from the 0-40 cm soil layers, while in HCD it was from the was 0-20 cm soil layer; for YMD it was from 0-120 cm; for MXD, it was from 0-40 cm and from 120-200 cm. The rotational fallow system has important effects on soil profile moisture differences, spatial variation in soil moisture, and grading. The soil moisture conditions under mulched corn were the best, and the information from this study provides a theoretical basis for the optimal allocation of land use patterns and design of crop rotation fallow patterns in the Hill and Gully Regions on the Loess Plateau.

Key words: rotation fallow, land use method, soil profile moisture, spatial distribution