Ditch‐Buried Straw Return Improves Soil Physical Quality and Crop Biomass in Two Rice–Wheat Paddy Soil Systems

ABSTRACT

Ditch‐buried straw return (DB) is an innovative practice combining deep tillage and straw incorporation. This study aimed to evaluate its effects on soil physical quality compared to rotary tillage (RT) and identified key constraints to crop in sandy‐loam and clay‐loam paddy soils within rice–wheat systems. Two field experiments were conducted in two paddy soils. Soil physical properties and a comprehensive indicator—least limiting water range (LLWR)—were employed to evaluate soil physical quality. Compared with RT, DB decreased soil bulk density ( ρ _b ), penetration resistance, and increased SOC, infiltration rate ( K _v ), and available water content (AWC). Combined with the coupled changes in soil water retention, soil aeration, and mechanical impedance, DB has a larger LLWR than RT in both two paddy soils. The sandy‐loam soil exhibited a better physical quality with macroporosity > 5%, air capacity > 10%, and AWC > 15%, whereas the clay‐loam soil showed much higher ρ _b and poorer AWC. The wheat in the clay‐loam soil was promoted by the improved soil aeration and water permeability. While in sandy‐loam soil, wheat and rice benefited from the slight increase in ρ _b and decreased SOC in the topsoil layer, which may be attributed to the burial of excess straw from the topsoil into subsoil. These findings demonstrated that DB is an effective practice facilitating crop growth in rice–wheat rotation systems. Alleviating soil compaction and decreasing residue accumulation on the soil surface may serve as potential strategies promoting crop growth in clay‐loam and sandy‐loam soil, respectively.