Effects of tillage practices and slope on runoff and erosion of soil from the Loess Plateau, China, subjected to simulated rainfall

- AD, AH are more effective in reducing runoff and erosion, and increasing rainfall infiltration amount than CP.
- Tillage practices are more effective in decreasing erosion than runoff as the SRB (89%) higher than RRB (80%).
- The SRB and RRB of tillage practices are decrease with the increase of slope gradient.
- CP is effective in minimizing runoff and erosion, with an exception on steeper slope, which can accelerate erosion.

Soil erosion, particularly during summer fallow period, in sloped farmland has been identified as a critical threat to sustainable agricultural development in the Loess Plateau of China. However, the effects of varying tillage practices during the summer fallow period have not been fully investigated. The objective of this study was to determine the effects of tillage practices on runoff and sediment loss under plot (4.0 m in length and 1.0 m in width) rainfall simulations. Runoff initiation time, runoff amount, sediment loss and cumulative infiltration amount were recorded. One rainfall intensity (90 mm h−1, 40 min), three slopes (5°, 10°, and 15°) and four prevalent tillage practices (Artificial Digging, AD; Artificial Hoeing, AH; Contour Plow, CP; and Traditional Plow, TP) were studied. Two indices, runoff reduction benefits (RRB) and sediment reduction benefits (SRB), were selected to evaluate the effect of the practice on controlling runoff and sediment. Compared to TP treatment, the AD, AH and CP were more effective in reducing the magnitude of runoff amount and sediment loss as well as increasing the rain water infiltration amount. CP with a 15° slope was an exception in which the sediment loss increased. In general, the SRB was greater than the RRB for a given tillage practice under the same slope, suggesting that the benefits from sediment reduction were more effective than the benefits from runoff reduction. RRB and SRB were the largest for AD, followed by AH and CP, irrespective of slopes. The capacity of the three tillage practices to reduce runoff and sediment decreased as the slope increased. In particular, AD at a 5° slope had the best performance in reducing runoff and sediment loss; however, SRB and RRB were −57% and 1%, respectively, for a CP plot with a 15° slope. This finding suggested that CP had a higher sediment loss and a similar runoff amount compared to those of TP. These results of plot simulated rainfall will contribute to our knowledge about the effects of different tillage practices on soil erosion from sloped farmland.