Improved N application methods and N sources for corn in Southwestern Ontario

IPNI-2014-CAN-4RC02

29 Apr 2016

2015 Annual Interpretive Summary


Corn producers often apply N fertilizer by either streaming urea-ammonium nitrate (UAN) or broadcasting urea. They are considering adding inhibitors to reduce losses of applied N. Compared to other N sources, urea and UAN fertilizers have higher risks of ammonia loss. As with other N sources, denitrification and nitrous oxide (N2O) losses can also be substantial. The objectives of this project are to measure the impact of these N sources, and their timing and placement, on yields, ammonia loss and nitrous oxide emissions.

Phase 1 of this study compared treatments applied at sidedress in 2013 and 2014. The treatments investigated included three application methods (broadcasting, streaming, and band injecting N fertilizers) and three different N sources (the regular N source [urea for broadcast and UAN for streaming and injecting], the regular N source with a urease inhibitor and the regular N source with a urease inhibitor and a nitrification inhibitor). A control N treatment (zero rate) was included for comparison. The inhibitors and the band injection treatments had large beneficial effects. Compared to broadcast urea, on average over the two years, injection of UAN with urease and nitrification inhibitors increased yields by 19% to 174 bu/A, while reducing loss of ammonia-N from 54 to less than 1 lb/A, and reducing N2O-N emission during the growing season from an average of 2.1 to 1.5 lb/A.

Phase 2 of this study, started in 2015, expanded the treatments to include the timing of N fertilizer application, as well as source and placement. First-year results indicate that, as compared to broadcast urea applied at planting, sidedress injected UAN with urease and nitrification inhibitors reduced ammonia and nitrous oxide emissions by 91% and 57%, respectively, while increasing corn yield by 11%. This experiment is to be repeated in 2016 and 2017, because detailed results show strong interactions of the source, timing and placement factors with weather. The results from this project so far demonstrate that attention to 4Rs (right source, rate, time, and place) for N management can provide simultaneous benefits in productivity, profitability and environmental impact.