Effects of tillage practices on runoff and soil losses in response to different crop growth stages in the red soil region of southern China

Purpose

Tillage practices and crop growth play important roles in the soil erosion of sloping farmland. This study aims to investigate the effects of tillage practices on soil erosion in response to different crop growth stages and to determine the primary factors that affected the runoff reduction benefit of tillage practices among different growth stages.

Methods

A field study was carried out under natural rainfall conditions, and 12 runoff plots (20 m × 5 m) were established, including four treatments, i.e., flat planting (FP), flat planting with hedgerow intercropping (HG), longitudinal ridge (LR) and bare land (CK). Runoff and soil losses after each rainfall event were monitored during the peanut seasons of 2021 and 2022 and the effects of tillage practices and peanut growth stages on runoff and sediment yields were evaluated.

Results

The total surface runoff depth and sediment yield decreased in the following order: CK > LR > FP > HG. As peanuts grew, the seedling, needling, podding, and full fruit stages contributed approximately 71.5%, 20.4%, 6.4%, and 1.7% of the total runoff depth, respectively, which could be attributed to the synergistic impact of rainfall, crop growth, and antecedent soil moisture. During the seedling stage of peanuts, which did not provide sufficient surface cover, concentrated rainfall in large amounts resulted in high soil moisture and consequently high runoff losses. As peanuts grew, the S-shaped growth curve for peanut aboveground parts and root systems and reduced rainfall depth and frequency resulted in less runoff loss and increased runoff reduction benefits of tillage practices.

Conclusions

The early growth stage of peanuts, generally accompanied by high antecedent soil moisture and heavy rainfall, should attract more attention to improving water erosion conditions on sloping farmland with only longitudinal ridges.