A six-site field study on assessing the suitability of conservation and conventional tillage in the black soil region, Northeast China

In Northeast China’s primary granary, long-term conventional tillage (CT) has led to significant soil degradation in the high-fertility black soil. Conservation tillage (CS) presents an opportunity to preserve soil quality but may reduce crop yield. The suitability of CT and CS in black soil regions and underlying mechanisms are not clear. This study aimed to investigate the impact of CT and CS on soil quality, crop yield and associated influencing factors at a regional scale. A comprehensive field experiment spanning six sites across the black soil region was conducted to evaluate the effects of rotary tillage (RT, traditional practice), no-tillage (NT, a form of CS), and deep ploughing (DP, representing CT) on maize yield and soil physicochemical properties. Results revealed that NT significantly enhanced total and available soil nutrients, along with soil organic carbon (SOC) content in surface layer (0–20 cm), compared to RT. Conversely, DP improved these soil properties in the subsurface layer (20–40 cm) across various sites. Notably, SOC accumulation rates were higher in warmer than cooler regions under NT. NT also significantly increased soil water content throughout the entire growth season and subsequently decreased soil temperature during the seeding stage, particularly in semi-arid areas. DP slightly increased soil water content and maintained a similar soil temperature compared to RT in both semi-arid and semi-humid areas. Variable partitioning analysis (VPA) highlighted the significant influence of soil bulk density, nutrient contents, and hydrothermal properties on yield variation under NT and DP compared to RT. Under NT, these factors contributed to 77 %, 81 %, and 63 % of yield variation, respectively, while for DP, the contributions were 65 %, −33 %, and 70 %. Our findings suggest that NT effectively preserves soil quality, conserves water, and sequesters carbon in semi-arid areas, leading to optimal maize production. Alternatively, DP with straw incorporation shows more variable yields and promises more positive outcomes in semi-humid areas.