Abstract

Heavy metal cycles in horticultural systems in areas supplying vegetables to Mbare Musika were characterized with reference to the soil, water, fertilizers used and crops grown from different ecological zones of Zimbabwe. Apart from inherent soil heavy metal properties, anthropogenic sources contributed through irrigation water and fertilizers. Different areas specialized in growing peculiar vegetables through influence of environmental traits within the horticultural system. The soil in Mutoko, Rusape and Seke had high levels of cadmium and lead unlike in other study areas. The water was a major source of cadmium, cobalt and lead. Most soils within the study area had an acidic pH noted to promote heavy metals solubility hence makes vegetables contamination inevitable. Irrigation water is the challenge in most of the study areas. Generally, soil pH, irrigation water quality and fertilizers need to be regulated together with other soil amendment programs to break the cycle of heavy metals in the horticultural systems.

Key words:  Heavy metal, pH, cadmium, lead, maximum threshold, route, Mbare  Musika, horticultural system.