ABSTRACT Temporal variations in soil dynamic characteristics after subsoiling are closely correlated with soil quality and the effectiveness of subsoiling practices. Analyzing soil hydraulic characteristics not only provides a basis for identifying the presence of a soil plough layer, but also offers a novel approach to optimizing tillage timing and frequency, reducing tillage resistance, and thereby achieving the goals of low‐carbon and precision tillage. Aiming to address the data gap in soil characteristic parameters during the tillage cycle after subsoiling and clarify the mechanisms underlying subsoiling‐induced soil amelioration, the Mualem‐van Genuchten (MVG) hydraulic model with HYDRUS‐1D software was integrated, combined with EDEM‐based pore structure simulation, to systematically reveal the linkages between soil macro‐hydraulic performance, meso‐aggregate distribution and micro‐pore structure evolution. The core mechanism driving hydraulic improvement after subsoiling lies in plough pan fragmentation and pore structure reconstruction: subsoiling disrupts the compacted plough pan, increasing inter‐aggregate pore volume and reducing bulk density, which creates a continuous pore network facilitating water infiltration and gas exchange. Consequently, soil water retention capacity was remarkably enhanced while maintaining vertical permeability. Even after one year of cultivation, the water penetration rate of the soil remained 9.76–10.26 times higher ( p < 0.05) at 3 h after subsoiling than that of non‐subsoiled fields. Further, it was identified that fine soil aggregate enrichment (20–250 μm) mediates the improvement of water retention and plant root growth, as these aggregates form stable spaces that balance water storage and transmission. The increase in EDEM‐simulated pore expansion (8.21%–20.63%) corresponded quantitatively to MVG‐calculated water retention enhancement (12.31%–18.28% in Δθ₂), verifying that pore structure modification is the direct driver of hydraulic characteristic change. The EDEM soil model effectively captured the dynamic process of subsoiling‐induced soil structural rearrangement, while the MVG‐HTDRUS‐1D framework quantified the consequent hydraulic responses. This study elucidates the process‐based mechanisms by which subsoiling improves black soil quality, providing a theoretical basis and technical support for predicting tillage suitability and guiding precision/low‐carbon tillage in Northeast China.
Song et al. (Tue,) studied this question.