Long‐term Straw Mulching in a No‐till Field Improves Soil Functionality and Rice Yield by Increasing Soil Enzymatic Activity and Chemical Properties in Paddy Soils

Background The degradation in soil quality over the last four decades poses a major threat to the sustainability of the puddled transplanted rice (Oryza sativa L.) system in southern China. Conservation tillage practices (CTPs) such as no-tillage and crop straw mulching (SM) are considered effective strategies for achieving sustainable crop production. Aims This study aimed to assess the efficacy of different CTPs on crop yield and soil properties in an ongoing long-term field experiment (2008-2020), particularly changes in soil chemical properties and enzymatic activities and their relationship with rice grain yield. Methods Five treatments including conventional tillage (CT), CT and straw retention, CT and SM (CT-SM), no-tillage (NT), and NT and SM (NT-SM) were applied at a field scale over a period of 12 years. In Years 11 (2019) and 12 (2020), soil samples were collected at two depths (0-10 cm and 10-20 cm) after rice harvesting. Soil chemical traits, enzymatic activities, and rice production were measured in response to different CTPs treatments, and differences between treatments were assessed. Results Soil pH, soil organic carbon, total nitrogen (N), available N, total phosphorus (P), and available P were significantly higher in CTP treatments, compared with CT. The activities of soil enzymes including invertase, acid phosphatase, urease, catalase, beta-glucosidase, and cellulase were significantly higher in CTP soils, compared with CT soils. A general trend of lower enzyme activity was observed at the deeper soil depth. The NT-SM treatment fields consistently produced the highest grain yield and larges differences in edaphic properties relative to the CT fields; however, all CTP treatments lead to significant increases in grant yield and edaphic properties relative to CT. A correlation analysis demonstrated that the enhancement in soil enzymatic activities contributed to soil quality and grain yield of rice. Conclusions The results of this long-term field study indicate that the use of CTPs in paddy soil can benefit farmers in southern China by improving soil functionality and sustainability and the grain yield of rice.