Combined Effect of Cattle Dung and Urea Fertilizer on Organic Carbon, Forms of Nitrogen and Available Phosphorus in Selected Nigerian Soils

Incubation experiment was conducted on four soil types in Nigeria using cattle dung (CD) at the rate -1 -1 of 2.5g/kg soil ( 5 t ha ), Urea fertilizer at the rate of 0.1g/kg soil ( 200 kg ha ) and cattle dung -1 (2.5g/kg soil) combined with Urea 0.05g/kg soil (100 kg ha ) as treatments. The objective of the experiment was to compare the rate of OC, NH 4 – N, NO3 – N and available P release on soils selected from different agro ecological zones of Nigeria. Ten soil samples were collected and bulked from each of the sandy clay, sandy loam, sandy clay loam and loamy sand soils from three different locations within each soil type. The soils were arranged on completely randomized design in laboratory for 60 days. All the treatments reacted differently in each of the soil type in relation to OC, total N, NH4 – N, NO3 – N and available P. In sandy clay and sandy loam soils, all the treatments significantly increased (p 0.05) OC, total N, NH4 – N, NO3 – N and available P except OC in sandy loam compared with control. In sandy clay loam and loamy sand soils, all the treatments significantly increased (p 0.05) NH4 – N, NO3 – N and available P. Among all the treatments, CD had the highest OC in all the soil textural classes,, urea had the highest NH4-N and NO3-N while CD + urea had the highest available P (except sandy clay). Cow dung had the highest P in sandy clay. Sand loam and sandy clay loam had highest total N but urea recorded highest value of N in sandy clay while urea+CD mineralized equal amount of total

Mineralization Rates of Soil Forms of Nitrogen, Phosphorus, and Potassium as Affected by Organomineral Fertilizer in Sandy Loam

Farmers tend to use organomineral fertilizers as a result of inadequacies embedded in the sole use of organic and mineral fertilizers. A laboratory incubation study to determine the rate of the forms of N, P, and K released by organomineral fertilizer was conducted at Adeyemi College of Education, Ondo, southwest Nigeria, in 2013. Organomineral fertilizer (OMF) at the rates of 0, 0.125, 0.25, 0.5, and 1.0 g/100 g soil to represent 0, 2.5, 5, 10, and 20 t ha−1 OMF, respectively, was incubated for ninety days. The treatments were replicated three times and arranged in a completely randomized design. The determined forms of N were total N, NH4–N, and NO3–N; the forms of P were total P, solution P, and available P while the forms of K were total K, solution K, and exchangeable K. Organomineral fertilizer significantly increased N, NH4–N, NO3–N, total P, solution P, exchangeable P, solution K, and exchangeable K at all rates with different values. The rate of ammonification of N was higher than the rate of nitrification of NH4 + N to NO3 + N especially at 10 and 20 t ha−1 OMF. Application of 5 and 10 t ha−1 OMF could be used to increase soil forms of N, P, and K