An evaluation of the potential of humates in the reduction of ammonia volatilization

Abstract

Loss of nitrogen as ammonia from broadcast or shallow banded urea-based fertilizers can be substantial especially on the high pH soils typical of most parts of Western Canada. This reduces fertilizer efficiency and may contribute to environmental pollution. Minimizing ammonia volatilization can be accomplished by treating urea-based fertilizers with various commercially-available nitrogen stabilizers. However, costs, varying efficacies of N stabilizers and a simple method for evaluating ammonia volatilization in the field have limited the wide adoption of these technologies by farmers. A field experiment was carried out in Leroy, Saskatchewan where Urea Ammonium Nitrate (UAN) treated with humates was side-banded with wheat to a depth of about 3.8 cm in an alkaline clay loam soil. Treatments were replicated thrice. A simple method involving a passive dosimeter, a semi-open static chamber and a calibration equation was used to estimate ammonia volatilization. Results after 32 days showed that humates reduced ammonia volatilization by 54% compared to the control. This reduction may have been due to an increase in the soil’s cation exchange capacity by humates, as well as the temporary reduction of soil pH in the immediate vicinity of the fertilizer.