Spatial Distribution of Soil Moisture in Relation to Soil Redistribution by Intense Tillage in Purple Soils

In this study,consecutive tillage by hoeing was performed 45 times in an orthic regosol with thin soil layers,to simulate the impact of long-term tillage on soil moisture at different slope positions and different period.Soil water content of till layer was measured on 30-day-interval period using time-domain reflectometry(TDR) in different slope positions of the control plot and the treatment plot(plowed 45 times).The results showed that: A notable decrease in the depth of the soil profiles on the treatment plot occurred at the summit and shoulder slope positions,and an increase of the thickness of the soil profiles was found at the toeslope position,compared with those of the control plot.Intense tillage resulted in a decrease of soil water content by 8.74%~25.49% and an increase of variation in soil water content by 11.9%~399.8% for the soil layers of 0-16.5 cm as compared with control plot.Soil water content at the upper slope positions of the treatment plot was less than that of the control plot due to decreasing in depth of the soil profiles under intense tillage.However,no significant differences between the control plot and the treatment plot were found at the bottom positions,showing that an increase of depth of soil profiles at the bottom positions induced by tillage,had little impact on soil water content in till layer.Tillage resulted in an intense downslope transport of soil layer and the variation in soil water content at the summit and shoulder slope positions in steeply sloping fields.