Objective  The effect of tillage depth on soil moisture characteristics of red soil in sloping farmland is clarified in seasonal drought period.

  Method  The tillage depth experiment of red soil was conducted in 2015, including four treatments: no tillage (NT), ploughing 10 cm (P10), ploughing 20 cm (P20) and ploughing 30 cm (P30), and the effects of tillage depth on characteristics of soil moisture of red soil in sloping farmland under seasonal drought were studied.

  Result  After heavy rain, the 0-60 cm soil layer of red soil had the best rainwater storage capacity in P30 treatment, followed by P20 treatment, while P10 and NT treatments were relatively poor, and the tillage depth had a significant effect on the rainwater storage capacity of 0-30 cm soil layer (P < 0.05), but had no significant effect on the rainwater storage capacity of 30-60 cm soil layer (P > 0.05). Multivariate analysis of variance showed that tillage depth had an extremely significant effect on soil water content in 0-60 cm soil layer in red soil under seasonal drought period (P < 0.01), and the interaction between tillage depth and other influencing factors (such as soil depth and observation duration) also had an extremely significant effect on soil water content (P < 0.01). P30 treatment led to rapid soil water consumption in plough layer and sub topsoil, which was not conducive to the stability of soil water content. Shallow ploughing and no tillage increased the consumption of soil water in the sub topsoil, the change of soil water storage of P20 treatment was the smallest, which was 2.26%-11.79% lower than that of other treatments.

  Conclusion  Ploughing 20 cm is conducive to rainwater storage, and the water consumption is the least under seasonal drought period, which is most conducive to the stability of soil water content in 0-60 cm soil layer under seasonal drought period. The research results provide a certain theoretical basis for soil water regulation in red soil sloping farmland during seasonal drought period.