Effects of tillage alteration on soil water content, maize crop water potential and grain yield under subtropical humid climate conditions

Seasonal drought stress is common in farmland even under humid climate conditions. Low soil water content and high penetration resistance in clayey soil are both factors that limit crop growth, which is significantly affected by tillage. In a two-year (2014-2015) field experiment conducted in Hubei, China, the effects of conventional tillage, along with occasional deep tillage and no-till, on the soil water content and penetration resistance values of red soil and on the crop water potentials of the maize crop (Zea mays L.) were tested. Compared to conventional tillage, deep tillage reduced the difference in the soil water characteristic curve between 0-40 cm soil layers, resulting in a more loose and homogeneous topsoil. The deep tillage significantly (p<0.05) decreased soil penetration resistance, increased soil-available water content and soil water content during the dry period, promoted an increase in maize root density by 11.4 similar to 31.6%, and increased the water potential of the maize root and leaf during most growth stages. In contrast, the effect of no-till was opposite to that of deep tillage, reducing maize grain yield by 25.3 similar to 26.3%. The results confirmed that no-till is not appropriate for the clayey red soil but rather that tillage is needed. This suggests that occasional deep tillage is helpful in mitigating seasonal crop drought stress under the conditions of a humid climate.