Effects of liquid modified rabbit waste on micronutrients and heavy metals in soil and their uptake in maize plant

Abstract

This study evaluated the impact of liquid organic fertilisers (LOFs) derived from rabbit waste on heavy metals (Cr, Cd, Pb, Ni) and micronutrients (Zn, Fe, Mn, Cu) in soil and their uptake in maize plant. Eight LOF formulations produced from urine and faeces of rabbits fed with either 100% forage or 50% forage plus 50% concentrate were compared against NPK and control using a randomised complete block design. Results demonstrated that the LOFs significantly enhanced plant uptake of essential micronutrients. The UfFfRN (forage-fed rabbit's urine and faeces with banana root and neem) treatment achieved the highest Cu uptake (0.12 kg ha^-1 ) and Mn uptake (0.58 kg
ha^-1 ). The UсfCbRN (concentrate and forage-fed rabbit's urine with corn cob and banana root and neem) treatment had the highest Zn uptake (0.08 kg ha^-1 ), while Fcf (concentrate and forage-fed rabbit's faeces) treatment had the highest Fe uptake (0.16 kg ha^-1). Liquid organic fertilisers effectively maintained heavy metal concentrations in maize below FAO/WHO thresholds, with Cd, Cr, Pb, and Ni uptake remaining low across all treatments. Post-harvest soil analysis revealed increased Fe levels, with UсfFcfRN showing the highest concentration (6.77 mg kg^-1) due to organic matter decomposition. Zinc concentrations generally decreased after harvesting, while UfCbRN showed lower post-harvest Pb and Cd concentrations, potentially due to immobilisation. These findings support the agronomic efficiency and environmental safety of rabbit waste-derived LOFs for sustainable soil fertility management in tropical maize systems.