Can application of enhanced efficiency fertilizers at planting reduce N losses from grain corn production in Ontario?


01 Jun 2018

2017 Annual Interpretive Summary

Nitrogen (N) is a key input for sustaining high crop yields, but fertilizer N uptake efficiency in crops is relatively low. Part of the applied N that is not taken up by crops, is vulnerable to losses such as nitrate leaching and nitrous oxide emissions. The overall goal of this project is to determine how Right Time and Right Source practices for N fertilizer management affect N losses.

Nitrous oxide emissions were monitored continuously using micro meteorological towers, with 12 observations per day. Nitrate losses were assessed using soil solution samplers installed at a depth of 30 inches. Four plots, each ten acres in size, received four different N fertilizer treatments: two with urea applied pre-planting and two with urea-ammonium nitrate (UAN) applied as sidedress at the 6th leaf stage. At each timing, the fertilizer is applied with and without inhibitors of urease and nitrification.

Monitored over the 80 days following N fertilizer application, nitrous oxide emissions were reduced by about 40% in two out of three years in response to inhibitors applied with urea, and by about 50 to 60% in response to inhibitors applied with UAN. In one year of three, nitrous oxide emissions were reduced by 75% when UAN was applied with inhibitors in comparison to urea without. Nitrate leaching and corn yield differed little among treatments.

This experiment has shown a substantial and robust reduction in nitrous oxide emission in response to the use of urease and nitrification inhibitors. These results come at an opportune time to inform concurrent development of a certification program for 4R Nutrient Stewardship, supporting quantification of benefit to the environment.