Evaluating the Influence of Deep Tillage Depth and Complementary Technologies on Soil Properties and Maize Yield: Evidence From a Meta‐Analysis

ABSTRACT Deep tillage (DT), one of the key technologies for protecting black soil, is crucial for combating soil compaction in the Black Soil Region of Northeast China (BSRNC). However, due to the small implementation scope of DT, it is still difficult to comprehensively solve the compaction problem. At the same time, the effectiveness of DT is restricted by regional environmental conditions, and the suitability configuration is still unclear, which restricts its precise promotion in BSRNC. Therefore, this study employed 436 data sets for a meta‐analysis to assess the impact of DT depths (20, 25, 30, 35 cm) and complementary technologies, such as deep tillage alone (DT), straw return (DTS), organic fertilizer application (DTM) and the combination of the two (DTMS) on soil properties and maize production. Based on the theory of Earth Critical Zone Science, a DT suitability prediction framework was constructed to systematically integrate multi‐level factors such as climate, topography, soil, and hydrology to reveal their response relationship with different DT. Results showed DT at ≥ 30 cm significantly improved soil fertility (SOC, TN), reduced bulk density (BD), and enhanced yield, with 35 cm depth achieving the greatest increases. Direct effects of DT measures on maize and indirect regulation through soil properties jointly drove the increase in yield, while climatic conditions (mean annual precipitation) and topographical factors (slope and altitude) determined the selection of DT depths and complementary technologies. The regional suitability analysis indicated that the 35DTS and 35DTM were optimal in areas with high elevation (> 300 m), high precipitation (650–750 mm), and high SOC content (> 30 g/kg). The results further clarified the role of natural climatic conditions, soil properties, and geological‐hydrological factors in determining the effectiveness of DT, and emphasized the necessity of implementing region‐specific and precision‐based DT strategies. This study offers practical guidance for the promotion of DT in BSRNC and further contributions to food security.