Improved Nitrogen Application Methods and Fertilizer Additives to Reduce N Losses through Ammonia Voltilization, Nitrous Oxide Emissions and Nitrate Leaching.

In 2010, there were about 4.2 million tonnes of N fertilizer products used in Canada with urea being the dominant N source at 45.8% and UAN at 22.4% of all N fertilizer sales. Ammonium nitrate fertilizer only represented 2.4% of N fertilizer usage. With increased application of urea-based fertilizers and UAN solutions to field crops, ammonia volatilization losses from just these two forms may exceed 186,000 t N in Canada  at a fertilizer replacement cost of $259 million/yr.  Increased farm sizes have resulted in greater time constraints for producers to apply nitrogen fertilizers to crops. Hence, some producers have now started applying their N by either streaming UAN onto their soils or are considering adding inhibitors with urea or UAN to reduce losses of applied N without knowing how effective these management practices are from a crop utilization perspective. Hence we evaluated N fertilizer application methods (broadcast, banded and streamed and fertilizer N additives (control, urease, urease and nitrification inhibitor) on ammonia volatilization, nitrous oxide emissions and corn N uptake on a Brookston clay loam soil in South-western Ontario.  Broadcasting urea resulted in the greatest ammonia volatilization losses followed by injection and streaming.  The addition of urease inhibitors decreased ammonium volatilization losses compared to regular urea or UAN fertilizers.  Injecting sidedress N fertilizers increased N uptake in both grain and total above-ground biomass compared to either broadcasting or streaming N fertilizers.  The inclusion of inhibitors (urease with/without a nitrification inhibitor) resulted in the greatest yields and above-ground biomass.  Nitrogen application methods were found to influence nitrogen losses from soils and the inclusion if inhibitors reduced losses and enhanced N uptake and crop yields.  Hence management practices could and should be modified to enhance nitrogen fertilizer utilization by crops and thereby improve environmental quality.