Effects of Percarbamide and Two Nitrogenous on pH, Nitrogen Transformation, and Exchangeable Metal Ions in Soil from Banana Plantations

Effects of percarbamide, urea, and ammonium sulphate on the pH, nitrogen transformation, and contents of exchangeable metal ions, i.e., Mn, Cu, Ca, Mg, Fe and Al, in soil from banana plantations were studied in an indoor incubation experiment that included a static and a dynamic test. The results from the static test showed that the soil pH increased with increasing percarbamide and urea, but it did not responded to the added ammonium sulfate, while the exchangeable Al was negative correlated with pH in the soil. The dynamic test demonstrated that the soil pH decreased with a prolonged incubating time, as the exchangeable Al had a negative correlation with the soil pH; and, the ammonium nitrogen in soil increased initially and followed by a decrease to reach a constant state till the end, while the nitrate nitrogen content tended to rise continuously. On the exchangeable metal ions, the concentrations of Mn and Mg showed an upward trend, that of Cu increased at first and then decreased, and that of Ca decreased initially but increased later on in the soil with a percarbamide application. In the soil with added urea, Mn, Ca and Mg showed an overall increasing trend, and Cu a downward trend, while Fe appeared unaffected. Whereas, the application of ammonium sulphate resulted in general declines on Mn, Ca and Cu with an increase on Mg in the soil, while no significant difference on Fe.