Time‐Dependent Effects of Subsoil Chiselling on Soil Physical Resilience in a Semi‐Arid Soybean‐Wheat Cropping System

ABSTRACT Sub‐surface soil compaction restricts root growth and water movement in intensively cultivated semi‐arid croplands. Chiselling is commonly used to alleviate compaction, but its effects are often short‐lived under variable rainfall conditions. We evaluated the time‐variable effects of chiselling on soil hydro‐mechanical properties (penetration resistance [PR], bulk density [BD], hydraulic function [steady‐state infiltration, IR; field‐saturated hydraulic conductivity, K fs ] and soil moisture dynamics), root traits (length, volume, surface area and diameter), yield and water use efficiency (WUE) in a soybean‐wheat rotation on a sandy loam soil over 2 years. Four treatments were evaluated: residual chisel (RS; May 2011), repeated chisel (RC; May 2011 and May 2013), fresh chisel (FC; May 2013), and no chisel (NC). At early soybean 2013, the compact layer (15–30 cm) showed 20%–22% lesser PR in RS and RC than NC ( p = 0.019); BD reductions mirrored this pattern. Despite greater PR, NC initially exhibited the highest IR (1.36 cm h −1 vs. RS 0.79, RC 1.08, FC 0.90 cm h −1 ) and K fs (1.10–1.19 cm h −1 , 31%–82% above chiselled plots at 15–30 cm), consistent with a dual‐porosity mechanism in which a few continuous biopores govern near‐saturated flow while the surrounding matrix remains strong. Root responses concentrated at 15–30 cm. RS/RC increased root length, volume and surface area and moderately enlarged mean diameter relative to NC/FC ( p < 0.05). Yield gains and improved WUE were observed in soybean in year 1 under RS (21% and 10%) and RC (32% and 17%) versus NC, whereas wheat yield did not differ; WUE was modest. Rainfall timing explained the short‐lived FC gains. The first 14 days after chiselling (20 May 2013) were dry, followed by two storm clusters within days 15–60 totaling ~330 mm, including ≥ 50–100 mm single‐day events. These high‐load, antecedently wet events plausibly collapsed freshly created voids in FC, truncating hydraulic gains, while RS/RC retained some storage advantages. The findings highlight that the effectiveness of chiselling is strongly time‐ and rainfall‐dependent, and their persistence depends on pore‐network continuity. Results suggest site‐specific, rainfall‐informed tillage decisions to enhance soil structural resilience and sustainable productivity in semi‐arid systems.