Influence of Municipal Refuse Waste Used as Fertilizer on Soil Physical and Chemical Properties in Selected Local Government Areas of Kano State

This study examined the effects of Municipal Refuse Waste (MRW) used as fertilizer on soil physical and chemical properties in three Local Government Areas of Kano State, Nigeria. Nine farmlands using MRW (three each from Fagge, Ungogo, and Dawakin Tofa Local Government Areas) and three control farms that did not utilize MRW were selected for this study. Each farms were divided into three strata, five surface (0–15 cm) soil samples were randomly collected from each strata and merged to form a composite sample. These samples were analyzed for texture, chemical composition, and heavy metal content. The results showed that all soils had a loamy sand texture, but MRW-treated soils had lower sand content (77.22–78.55%) and higher silt (15.00–17.67%) and clay (4.89–7.78%) contents compared to the control (82.77% sand, 13.23% silt, 4.00% clay), suggesting better soil structure and moisture retention. MRW-amended soils had slightly lower pH (6.054–6.322) than the control (6.403), likely due to organic matter breakdown. Organic carbon levels were significantly higher in treated soils, with Fagge and Ungogo soils recording 0.7909% and 0.7643%, respectively, compared to 0.2733% in the control. Exchangeable nutrients like calcium (3.327–2.317 cmol/kg), magnesium (2.770–2.033 cmol/kg), and sodium (0.2804–0.2725 cmol/kg) were also higher in treated soils than in the control (Ca: 1.202 cmol/kg, Mg: 1.264 cmol/kg, Na: 0.2154 cmol/kg). The highest total exchangeable bases (6.649 cmol/kg) were found in Fagge, while the control had only 2.805 cmol/kg. Phosphorus and nitrogen levels also increased as a result of MRW usage, with Fagge soils having the highest phosphorus (30.81 mg/kg) and nitrogen ranging from 0.1027% to 0.1680% in treated soils versus 0.1587% in the control. Heavy metals such as iron (11.29–12.10 mg/kg), manganese (18.77–26.25 mg/kg), zinc (10.05–38.94 mg/kg), and chromium (0.03874–0.05179 mg/kg) were elevated in MRW-treated soils compared to the control (Fe: 6.11 mg/kg, Mn: 11.85 mg/kg, Zn: 4.01 mg/kg, Cr: 0.0335 mg/kg). While most metals stayed within safe limits, lead in Ungogo (1.9571 mg/kg) exceeded the recommended threshold (0.5 mg/kg). Municipal Refuse Waste application improved soil fertility, particularly in urban areas like Fagge, by boosting nutrient levels and organic matter. However, proper waste treatment and continuous monitoring are necessary to prevent heavy metal buildup and ensure safe agricultural use of MRW.