Root Spatiotemporal Distribution, Soil Properties and Grain Yield Responses of Wheat ( Triticum aestivum L.) to 22 Years of Conservation Tillage and Short‐Term Compaction

ABSTRACT Effective long‐term tillage practices are crucial for maintaining winter wheat production under traffic‐induced soil compaction on the North China Plain. This study aimed to explore how 22 years of long‐term tillage history influences soil conditions, root spatial and temporal distributions, and yield responses to short‐term compaction. A 2‐year sub‐plot field experiment was carried out under long‐term conservation tillage practices: moldboard ploughing with maize residues incorporated (MC) and no‐tillage with maize residues covered (NC). Short‐term soil compaction (STC) was applied once, 29 days after sowing, during the 2023–2024 season to create CMC (compaction on MC) and CNC (compaction on NC), whereas no compaction was applied in 2024–2025. In 2023–2024, NC revealed slightly higher surface soil bulk density (SBD) and soil penetration resistance (SPR) than MC, even without short‐term compaction, whereas CMC increased mean SBD by 3%–6% and reduced total porosity by 4%–8% in the 0–20 cm layer compared with MC. CNC showed the greatest deterioration in soil physical properties, with the highest SBD, SPR and lowest porosity in the surface soil. Soil moisture was generally higher under NC but declined under compaction, particularly in CNC. Compaction also reduced microbial biomass carbon while increasing dissolved organic carbon, especially in the 0–20 cm layer. MC had the most extensive rooting (to 40 cm), whereas NC had moderately but substantially reduced rooting. CMC caused roots to shift upwards and decrease root length density, surface area, weight density, and volume below 20–30 cm, and CNC resulted in the most significant confinement of roots to the surface layer and the most significant repression of root morphological features and antioxidant enzyme functions. Root traits and nutrient availability partially recovered during the absence of further compaction in 2024–2025, but previous CNC plots still showed some constraints. Grain yield was a result of these soil‐root reactions: MC had the greatest mean (2023–2025) yield (8189 kg ha −1 ). The STC yield fell below MC, and the CMC yield was about 18% below MC, indicating evident yield penalties due to traffic. NC performed better than CNC, and compaction led to an additional yield reduction of approximately 14% relative to NC. Overall, the intermediate yields of NC (6713 kg ha −1 ) and CMC (6669 kg ha −1 ) were statistically similar, whereas CNC exhibited the lowest yield (5751 kg ha −1 ). We conclude that long‐term tillage history is a major determinant of wheat responses to short‐term compaction. Therefore, selecting an appropriate long‐term tillage system is essential to reduce yield losses caused by traffic‐induced soil compaction.