Vegetable cultivation using river water, which may be polluted with heavy metals, can cause health problems to consumers. A study to establish cadmium and lead levels in water from Msasa, Manyame; Mukuvisi and Nyatsime Rivers was conducted in 2019. A questionnaire survey involving 105 randomly selected urban vegetable growers was conducted to examine farmer knowledge of the potential of polluted water to contaminate produce through heavy metals. Water, soil and vegetable samples were also collected and analysed for heavy metal presence using atomic absorption spectrophotometry. Results showed that some farmers (62%) were aware that wastewater could contain heavy metals. The majority of farmers (67%) applied phosphate-based fertilisers, a potential source of cadmium. Tested at P < 0.05, the results showed that sampled water from the four sites failed to meet the Standards Association of Zimbabwe 5560 (1997) standards. Cadmium tissue concentration from wastewater from Msasa and Manyame rivers was 1.3 and 1.17 mg g −1 respectively, which were 59 and 65 times higher than 0.02 mg g −1 from the control. Water from Manyame and Nyatsime rivers contains levels of heavy
This article describes the present institutional arrangements for irrigators’ resource access, agricultural support systems accessible to irrigators, and the various constraints irrigators experience. The survey acquired data from 101 snowballed respondents for the quantitative phase of the study. The qualitative phase gathered information from four purposively selected focus group discussions. According to the findings, irrigators commonly gained access to production land through traditional authority (81.2%). Gender was a barrier to land access, where male-headed families had larger land sizes than female-headed ones (t=4.993, p=0.028). Concerning irrigation water, irrigators abstract it wherever they find access, without any institutional arrangement or restriction. The main limitations to irrigators’ water availability were competition and the drying out of the water source, particularly spring water. Government assistance was rare among independent irrigators. Smallholder support services tend to be distributed unevenly among South African smallholders, usually leaving independent irrigators unsupported. Lastly, irrigators experience constraints in their farming that government existing services have the potential to address. Therefore, this study proposes that the government recognize independent irrigators as possible drivers of poverty and food insecurities. The study recommends institutional inclusion and the extension of support systems to independent irrigators.
Increasing demands on freshwater and challenges in disposal of wastewaters encourage their use for irrigation. The study evaluated the effects of irrigation of signal grass (Urochloa decumbens) with sludgewater on leaching, uptake and retention of a range of elements in two contrasting soils in columns. The grass was grown on a sandy loam and a clay soil packed in plastic columns and irrigated for 119 days with either undiluted, diluted sludgewater or tap water. The sludgewater had a pH of 6.9 and high aluminum (Al), manganese (Mn), iron (Fe), and boron (B). Analyses were conducted on leachates, above-ground plant biomass (two harvests), and soils at the end of the experiment.Sludgewater treatments increased grass biomass yield and uptake of nitrogen (N), phosphorus (P), potassium (K), and magnesium (Mg) in both soils with a greater nutrient uptake from the clay than the sandy loam. The application of sludgewater increased Mn and reduced P (sandy loam only) in the leachate with no effects on Al, Fe, or B. Uptake of Al, Fe, and B was increased by sludgewater application. Even when diluted, the sludgewater increased extractable Mn, particularly in the clay soil. The findings showed that irrigation of the soils with sludgewater increased Mn and B concentrations and uptake by signal grass, with no negative effects on biomass production. Leaching and accumulation in the soils of toxic elements were minimal in the short term. Sludgewater can therefore be used to grow signal grass in both soils although these effects need to be evaluated under field conditions.
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