Abstract
Organic waste materials as soil amendments are one of the topical approaches applauded for achieving sustainable agriculture world-over. The objective of this study was to investigate the effect of urban-based biosolid waste (UBBW) application on heavy metals (Cr, Cu, Zn and Pb) bioaccumulation by maize (Zea mays L.) plants. A pot experiment was conducted three times, using an acid Ferralsol from Makerere University Agricultural Research Institute, Kabanyolo (MUARIK) in Uganda. Treatments included the application of three types of UBBW, namely sewage, brewery and abattoir, each applied independently at the rates of 0, 50 and 100 g per pot filled with 4 kg soil. This was equivalent to 0, 2.5 and 5.0 metric tonnes of dry materials per hectare. Phosphorus fertiliser was also applied at 0, 0.795 and 1.591 g P per pot, equivalent to rates of 0, 25 and 50 kg P ha-1. The brewery waste applied at rates ≥ 2.5 t·ha-1 and phosphorus at 25 kg P ha-1 resulted in shoot Cu concentrations below the World Health Organisation (WHO) safe limit (73.3 mg·kg-1); and Zn slightly above the WHO safe limit (99.4 mg·kg-1). In contrast, the concentrations of chromium in the maize plants were well above the WHO safe limit (2.3 mg·kg-1), irrespective of the applied type of UBBW. Shoot metal bioaccumulation followed the order zinc > copper > chromium, with Pb being below the detection limit. The safest UBBW was abattoir waste; while the least environmentally suitable was sewage waste. It is clear that irrespective of the type of UBBW, their application to Ferralsol causes less bioaccumulation of Pb and Cr in maize plants compared to Zn and Cu.
Highlights
Heavy metals often impact human and animal health through unregulated urban waste disposal and when some materials are used for soil productivity amelioration
Sewage sludge was the richest in nutrients and heavy metals profiles among the biosolids considered in this study
Application of P enhances the rate of bioaccumulation of Zn and Cr heavy metals
Summary
Heavy metals often impact human and animal health through unregulated urban waste disposal and when some materials are used for soil productivity amelioration. Extensive studies have been done on the microbiology and pathogenicity of these materials [4] [5], empirical information related to the status of heavy metals, their soil loading and plant uptake capacities, and sorption/ desorption patterns is still lacking. The absence of such vital information is a recipe for resource misuse or abuse and risks the lives of unsuspecting farmers and consumers of produce from recipient gardens. Plant heavy metal bioaccumulation studies are critical in understanding and leveraging the natural soil’s capacity to attenuate and regulate the concentrations of these metals in plant-available forms
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
