Using biochar, compost, and dry-based organic amendments in combination with mycorrhizae for mitigating heavy metal contamination in soil.

Abstract

Water scarcity has led to the increased use of untreated wastewater for irrigation, contributing to heavy metal (HM) accumulation in soils and crops. This study evaluated the effectiveness of organic amendments and arbuscular mycorrhizal fungi (AMF) in reducing HM bioavailability and enhancing plant growth. A two-year pot experiment (2022-2023) was conducted using eight treatments (T1-T8) and three replicates each. Treatments included: T1 (Control), T2 Rice straw, T3, rice straw compost, T4, rice straw biochar, T5, AMF, T6, Straw + AMF, T7, compost + AMF, and T8, biochar + AMF. Post-harvest analysis showed that T7 and T8 significantly reduced soil and plant HM levels. T8 was the most effective, reducing Pb, Cd, and Ni in grains by up to 93%, 76%, and 83%, respectively. Shoot HM concentrations declined by 22%-52%, and grain uptake dropped by 58%-92%. T8 also improved shoot and root dry weights by 66% and 48%, and grain yield by 56%. Root colonization and mycorrhizal intensity increased significantly, along with urease (78%) and catalase (156%) activities. Results highlight the potential of T8 (biochar + AMF) as a sustainable strategy for remediating contaminated soils and improving crop productivity.