Impacts of Emerging Agricultural Practices on Groundwater Quality in Kahe Catchment, Tanzania

• Main Authors: Zuberi D. Lwimbo, Hans C. Komakech, Alfred NN. Muzuka
• Format: Article
• Language: English
• Published: MDPI AG 2019-10-01
• Series: Water
• Subjects: intensive irrigation; groundwater quality; heavy metals; fertilizers; pesticides; kahe catchment
• Online Access: https://www.mdpi.com/2073-4441/11/11/2263

This paper assesses the impacts of farmers’ intensive use of agrochemicals (fertilizers and pesticides) on groundwater quality in the Kahe catchment. Samples were collected during the wet and dry seasons of the year 2018 and analyzed for the presence of agrochemicals in the water. Groundwater chemistry was dominated by magnesium-sodium-bicarbonate (Mg-Na-HCO₃^−). The cations levels were in the trend of Mg²⁺ >Na⁺ > Ca²⁺ > K⁺, whereas anions were HCO₃^− > Cl^− > SO₄^2− for both seasons. The NO₃^− had an average value of about 18.40 ± 4.04 and 7.6 ± 1.7 mg/L in the wet and dry season, respectively. Elevated levels of nitrate, sulfate, phosphate, and ammonium were found in water samples collected near the large-scale sugarcane plantation in the catchment. For both seasons, Pb, Cd, Fe, Mn, Zn and Cu concentrations averaged approximately 0.08 ± 0.03, 0.11 ± 0.03, 0.16 ± 0.02, 0.11 ± 0.01, 0.46 ± 0.05, and 0.55 ± 0.02 mg/L, respectively. On the other hand, the concentrations were higher in shallow wells than in the deep boreholes. Pesticides’ residues were below the detection limit in all sampled groundwater. The findings from this study provide important information for intervention in groundwater quality management in Kahe Catchment, Tanzania.