Biochar influences growth performance and heavy metal accumulation in spinach under wastewater irrigation

Abstract

This pot-based study investigated the influence of cow-manure-derived slow pyrolyzed biochar on the growth performance and accumulation of Nickle (Ni), Zink (Zn), Copper (Cu) and Iron (Fe) in the aboveground plant biomass of spinach (Spinacia oleracea L.) grown under wastewater and groundwater irrigation. Biochar was applied in soil with or without manure (mixture of dung of cow and sheep/goat) at 3, 5 and 10% rates. Biochar application at 5% and when co-applied with manure at all application rates increased aboveground plant biomass under wastewater and groundwater irrigation. Application of biochar at 5 and 10% rates and when co-amended with manure at all application rates, increased the leaf area index under wastewater irrigation but caused no influence under groundwater irrigation. Biochar amendment at 5% rate reduced while at 10% rate and when co-applied with manure at 3 and 5% application rates increased root biomass under wastewater irrigation. Under groundwater irrigation, amendment of biochar at 10% and when co-applied with manure at 3 and 10% increased root biomass. Under wastewater irrigation, application of biochar tended to reduce the concentration of Ni when co-amended with manure while increased the concentration of Cu in aboveground plant tissues at 3 and 5% rates and when co-applied with manure at 10% rate. In conclusion, manure-derived biochar increased crop growth performance and influenced accumulation of heavy metals in aboveground plant tissues under wastewater and groundwater irrigation. Application of manure with biochar reduced concentration of Ni under wastewater irrigation and enhanced crop growth performance under groundwater irrigation.