Effects of Co-composting of Municipal Solid Waste and Pigeon Pea Biochar on Heavy Metal Mobility in Soil and Translocation to Leafy Vegetable Spinach.

An experiment was conducted to study the effects of co-composted products of municipal solid waste (MSW) and pigeon pea biochar (PPB) on heavy metal mobility in soil and its uptake by spinach. Application of municipal solid waste biochar co-compost (MSWBC) significantly (p ≤ 0.05) reduced the heavy metal content in spinach leaves and roots compared to municipal solid waste compost (MSWC) amended soil. The percent decrease in spinach leaf following the application of MSWBC-10% PPB compared to MSWC was 20.62%, 28.95%, 36.02%, 41.88%, 41.50%, and 41.23% for Cu, Cd, Pb, Cr, Ni, and Zn, respectively. The dry matter yield of spinach and soil organic carbon (SOC) content in soil amended with MSWBC-10% PPB was significantly increased by 32.75% and 47.73%; and 17.62% and 27.45% relative to control and MSWC amended soil. The study concludes that co-composted product, MSWBC, stabilized heavy metals in MSW, reduced their uptake by spinach and thus making it a viable option for safe disposal of MSW.

Effect of Soil Amendments on Microbial Resilience Capacity of Acid Soil Under Copper Stress.

An incubation study was undertaken to study microbial resilience capacity of acid soil amended with farmyard manure (FYM), charcoal and lime under copper (Cu) perturbation. Copper stress significantly reduced enzymatic activities and microbial biomass carbon (MBC) in soil. Percent reduction in microbial activity of soil due to Cu stress was 74.7% in dehydrogenase activity, 59.9% in MBC, 48.2% in alkaline phosphatase activity and 15.1% in acid phosphatase activity. Soil treated with FYM + charcoal showed highest resistance index for enzymatic activities and MBC. Similarly, the highest resilience index for acid phosphatase activity was observed in soil amended with FYM (0.40), whereas FYM + charcoal-treated soil showed the highest resilience indices for alkaline, dehydrogenase activity and MBC: 0.50, 0.22 and 0.25, respectively. This investigation showed that FYM and charcoal application, either alone or in combination, proved to be better than lime with respect to microbial functional resistance and resilience of acid soil under Cu perturbation.