EFFECT OF COW DUNG INCUBATION ON SOME PHYSICOCHEMICAL PROPERTIES OF A TROPICAL SOIL

This study investigated the effects of cow dung incubation on selected physicochemical properties and sulphate sorption of a tropical soil at Bayero University Kano, Nigeria, within the Sudan Savanna agro-ecological zone. Soil samples were collected from two profile pits and separated into Ap, Bt1 and Bt2 horizons. The samples were incubated with cow dung manure at application rates of 0, 10 and 20 g/kg for two weeks. Laboratory analyses covered soil pH, particle-size distribution, available phosphorus, organic carbon, organic matter, exchangeable bases, iron and sulphur. Sulphate sorption was evaluated following the application of potassium sulphate solutions and 24 hours of shaking. Initial soil pH values were 6.88, 5.53 and 5.80 in the Ap, Bt1 and Bt2 horizons, respectively, while cow dung had a pH of 8.37. Sand content decreased from 80% in the Ap horizon to 62% in Bt2, whereas clay content increased from 8% to 28%. Available phosphorus, organic carbon, organic matter, calcium and magnesium generally declined with depth. Cow dung contained 456.18 mg/kg total phosphorus and 92.86 mg/kg sulphur. Following incubation, manure-treated samples recorded higher organic carbon and extractable potassium values than untreated controls, with the highest reported organic carbon values at 10 g/kg. Sulphate sorption increased with depth in both profiles, ranging from 129.7 to 166.8 mg/kg in Profile 1 and 145.3 to 175.5 mg/kg in Profile 2. The results suggest that cow dung can contribute nutrients and influence selected soil chemical properties, while subsurface horizons retained more sulphate under the experimental conditions.