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, where MRW mainly contained decomposed organic matter, food residues, ash, and limited inert materials, with variable composition that may influence soil and environmental outcomes. Nine farmlands applying MRW and three control sites without MRW were selected. Each site was stratified, and five surface (0–15 cm, because the cultivated arable crops obtain most nutrients within the rhizosphere zone) soil samples were randomly collected per stratum and composited. However, further work will consider 15–30 cm layers to assess nutrient and metal leaching. Samples were analyzed for texture, fertility, and metal content using standard laboratory methods.
Results revealed loamy-sand textures across all soils, with MRW-treated soils showing lower sand (77.22–78.55%) and higher silt (15.00–17.67%) and clay (4.89–7.78%) fractions than the control (82.77% sand, 13.23% silt, 4.00% clay). Soil pH (6.05–6.32) slightly decreased compared with the control (6.40). Fertility parameters, including organic carbon (up to 0.79%), likely due to organic matter decomposition, total nitrogen (0.10–0.17%), available phosphorus (up to 30.81 mg kg⁻¹), and exchangeable bases such as calcium (2.32–3.33 cmol kg⁻¹) and magnesium (2.03–2.77 cmol kg⁻¹), were significantly enhanced.
Heavy-metal concentrations were determined using mild acid extraction (0.5 M HCl + 0.012 M H₂SO₄) and Atomic Absorption Spectrophotometry, which measures available fractions (bioavailable). Iron ranged from 11.29–12.10 mg kg⁻¹, manganese 18.77–26.25 mg kg⁻¹, zinc 10.05–38.94 mg kg⁻¹, and chromium 0.0387–0.0518 mg kg⁻¹. Lead levels exceeded safety limits in some sites, notably Ungogo. Although MRW improved soil fertility, variation in its composition and elevated metal levels highlight the need for cautious use and deeper assessments to evaluate long-term environmental and food-safety implications.
