The influence of tillage practices on soil detachment in the red soil region of China

Intensive cropland soil erosion can be caused by disturbance activities. However, conservation measures have been reported to increase soil resistance and decrease erosion. Hydraulic flume experiments were conducted to measure the detachment rate of disturbed soil samples from a peanut field with five tillage practices. Hydraulic variables were adopted to estimate the soil detachment rate and to quantify the rill erodibility parameter. The disturbed soil detachment rates are substantially greater than those for comparable undisturbed soil experiments. The average disturbed soil detachment rates for the 5 different tillage treatments, from lowest to highest, are as follows: straw mulch (PC) < manure (PM) < peanut and orange intercropping (PO) < peanut and radish crop rotation (PR) < conventional downslope furrows (PF). The conservation measures (PC, PM and PO) have a limited effect on increasing the disturbed soil resistance under low flow energy conditions. Thus, the average rill erodibility is lower, and the critical shear stress is higher for the PC, PM and PO treatments than those of the PR and PF treatments. With a slope gradient steeper than 17.6%, there is no significant difference among the detachment rates of all treatments. A linear function of both flow rate and slope gradient can be used to estimate the disturbed soil detachment rate. Both stream power and flow shear stress are more effective than the unit stream power in predicting soil detachment rates. The stream power is the most effective predictor among the three hydraulic parameters studied. Instead of the power functions, the linear functions of the hydraulic parameters are suggested to quantify the disturbed soil detachment rates.