Effect of Humate on the rate of nitrogen mineralization and phosphorus availability in Nitisols and Ferrasols

Abstract

Humate is a new commercial soil amendment for crop production in Uganda. Its use as an agro-input has increased over years with wide adoption among several farmers. The product can regulate the loss of obnoxious gases and leaching when applied to the soil. However, its effects on N mineralization and P availability are not clearly understood. This study was conducted to evaluate the effect of Humate on the rate of nitrogen mineralization and phosphorus availability in Ferralsols and Nitisols. The two soil types were obtained from Mabira Forest for Nitisols and Kabanyolo-Wakiso for Ferralsols. The two soils were subjected to an incubation experiment for ten weeks with applied Humate at Makerere University Soil and Plant Analytical Laboratory. The Humate product was added at the soils at recommended rate (60g/mat of banana), double recommended rate (120g/mat of banana) and control (0 g/mat) recommended for banana and incubated for ten weeks. The application of Humate had a significant effect on P availability and N mineralisation which varied with the time of incubation of the different soil types. Results from laboratory analysis of incubated soils reveal that NO3 - and NH4 + mineralized in a pattern with soils treated with double recommended rates of humate > Humate treated soils at recommended rate> control). There was a decrease in available P from week 2 to week 10 of incubation in Nitisols treated with Humate compared to the control but Ferralsols registered an increase in the control compared to Humate treated Ferralsols. Variations in N mineralization and P availability suggest that Humate influences nutrient dynamics differently with soil types. Humate is an agro-product that can stimulate the rate of nitrogen leaching (threatening groundwater pollution) but also can led to the loss of N-source gases. The product should be used carefully in agricultural system to avoid effects on the environment