Subsoil tillage enhances wheat productivity, soil organic carbon and available nutrient status in dryland fields

Tillage practices during the fallow period benefit water storage and yield in dryland wheat crops. However, there is currently no clarity on the responses of soil organic carbon (SOC), total nitrogen (TN), and available nutrients to tillage practices within the growing season. This study evaluated the effects of three tillage practices (NT, no tillage; SS, subsoil tillage; DT, deep tillage) over five years on soil physicochemical properties. Soil samples at harvest stage from the fifth year were analyzed to determine the soil aggregate and aggregate -associated C and N fractions. The results indicated that SS and DT improved grain yield, straw biomass and straw carbon return of wheat compared with NT. In contrast to DT and NT, SS favored SOC and TN concentrations and stocks by increasing the soil organic carbon sequestration rate (SOCSR) and soil nitrogen sequestration rate (TNSR) in the 0-40 cm layer. Higher SOC levels under SS and NT were associated with greater aggregate -associated C fractions, while TN was positively associated with soluble organic nitrogen (SON). Compared with DT, the NT and SS treatments improved soil available nutrients in the 0-20 cm layer. These findings suggest that SS is an excellent practice for increasing soil carbon, nitrogen and nutrient availability in dryland wheat fields in North China.