In‒situ immobilization remediation, soil aggregate distribution, and microbial community composition in weakly alkaline Cd‒contaminated soils: A field study

Biochar has advantages of a large specific surface area and micropore structure, which is beneficial for immobilization remediation of heavy metal‒contaminated soils. A field experiment was conducted to investigate the effects of rice husk biochar (BC) (7.5, 15, and 15 t hm−2) on Cd availability in soils and accumulation in maize (Zea mays L), soil aggregate structure, and microbial community abundance. The results show that BC treatment promoted the formation of large aggregates (5–8 and 2–5 mm) and enhanced aggregate stability, whereas it decreased the proportion of ≤0.25 mm soil aggregates. The geometric mean diameter and mean weight diameter under BC‒treated soils increased by 9.9%–40.5% and 3.6%–32.7%, respectively, indicating that the stability of soil aggregates increased. Moreover, BC facilitated the migration of Cd from large particles (>0.5 mm aggregates) to small particles ( © 2021 Elsevier Ltd