Strategic tillage is a promising alternative to conventional and no-tillage: Evidence from a 12-year field trial in a double-cropped rice system

No-tillage (NT) has obvious advantages in reducing input and labour costs. However, some farmers have raised concerns about adapting continuous NT to manage farmland due to problems such as soil stratification and less yield. Therefore, occasionally targeted tillage (known as strategic tillage, ST) has been proposed as a flexible management measure. To evaluate the potential impact of a typical ST pattern on soil properties and yield, a 12-year positioning field trial was conducted with three tillage practices, including long-term no-tillage (NT), ploughing tillage (CT), and ST (3-year NT and 1-year CT), in an intensive double-cropped rice system in southern China. ST could alter soil physicochemical properties by reducing soil stratification and potentially increasing nutrient availability. ST alleviated the bulk density (BD) stratification caused by the continuous decrease in 0-5 cm BD and the continuous increase in 5-10 cm BD under NT, due to the periodic use of CT. Compared with NT and CT, ST increased the soil available K (AK) and available P (AP) concentrations without affecting the SOC or TN storage throughout the profile. However, ST lowered the soil acidification at the soil surface (0-5 cm) while increasing the risk of soil subsurface acidification. Relative to ST, yields with NT trended lower over time, and the yield gap between NT and ST increased as the experiment progressed. The multiyear average yield of ST was 0.31 t ha-1 higher than that of NT but lower than that of CT. ST had the potential to improve the low yield under NT. It may be related to the fact that the seed setting rate (the proportion of filled to total seeds) of ST was significantly higher than that of NT (p < 0.05). In conclusion, strategic tillage is a more sustainable tillage method than continuous no-tillage and ploughing tillage in double-cropped rice systems in southern China.