Short‐Term Effects of Different Tillage and Straw Return Practices on Soil Compression Characteristics in Northeast China

ABSTRACT Soil compaction was a critical constraint to agricultural productivity in Northeast China's arid farmlands, decreasing pore structure, water infiltration and crop growth. Although improper mechanised tillage exacerbated compaction, systematic evaluations of mitigation strategies remained limited. We compared six treatments: no‐tillage with straw return (NTS) and removal (NT), plough tillage with straw return (PTS) and removal (PT) and subsoiling tillage with straw return (STS) and removal (ST). Their effects on soil compression characteristics were evaluated through uniaxial confined compression tests, focusing on pre‐compression stress (σ p ), compressibility (Cc) and recovery coefficient (Rc). Results showed that plough tillage and subsoiling tillage altered soil compression characteristics, reducing σ p and increasing Cc and Rc compared to no‐tillage. Straw return further increased Cc and Rc relative to straw removal. STS exhibited the lowest σ p (133.3 kPa) in the subsoil. The alteration in soil mechanical behaviour was associated with reduced bulk density, enhanced soil organic carbon (particularly under STS in the subsoil, by 30.7%–102.8%) and structural stability. While the reduction in σ p suggests higher compressibility, the increases in Cc and Rc indicate greater soil pore space and recovery ability, alleviating the compaction risk. The partial least squares path model revealed that tillage practice was the primary factor influencing soil compression characteristics, with a negative total effect on σ p and positive total effects on Cc and Rc. In conclusion, subsoiling tillage with straw return (STS) was the optimal practice to improve soil physicochemical properties, structural stability and reduce compaction risk in Northeast China's loamy soils.