Impact of legume cover crops and maize stover incorporation on albic soil physical properties

Straw returning is a crucial strategy for addressing the issues of "thinning, compaction, and hardening" in black soil region. This study aims to compare the effects of different cover crops incorporation with maize straw on albic soil physical properties and maize yield. Field experiments included the following treatments: (1) Control without straw (AN); (2) Clover straw (AT); (3) Alfalfa straw (AS); (4) Adzuki bean straw (AV); (5) Maize straw (AM); (6) Clover + maize straw (AT+M); (7) Alfalfa + maize straw (AS+M); (8) Adzuki bean + maize straw (AV+M). The application rate was 6 000 kg·hm⁻² for maize and 2 000 kg·hm⁻² for leguminous crop residues. Under the premise of ensuring maize yield, straw returning significantly improves the physical properties of 10 - 20 cm soil, among them AV+M treatment exhibits the most significant improvement effect. Compared with AN, AV+M treatment significantly reduces the soil three-phase structure distance, soil bulk density and soil solid phase ratio by 51.5%, 9.79% and 5.21 percentage, respectinvely; increases the generalized soil structure index and gas phase ratio by 18.9% and 9.50 percentage, respectively. The total soil porosity and soil saturation water capacity were also increased by 5.21 and 7.51 percentage, respectively. Therefore, compared with maize straw return alone, the incorporation of maize and legume cover crop straw mixtures demonstrates superior effects, offering a novel approach for straw return technology in the black soil region of Northeast China.