Impact of fertilizer additives on N2O emissions for contrasting corn growing seasons in Canada

A side-by-side field-scale experiment was carried out in 2017-18 growing seasons with corn fertilized with urea +/- urease and nitrification inhibitors. April-May precipitation totalled 305mm in 2017 compared to 124mm in 2018. June-early July 2018 received only 70mm compared to 253mm in 2017.

The 2017 growing season was dominated by brief N2O emission peaks in early June, with the largest peak in early July following 17 rainy days. Inhibitors reduced N2O emissions by 9% the first 30 days after fertilization. The 2018 growing season had an extensive N2O emissions from 15-May to 26-June; the inhibitors reduced N2O emissions by 34%. 

The anthropogenic emissions of nitrous oxide (N2O) originate mainly from agriculture. N2O emissions are weatherdriven and are mainly a by-product of soil microbial nitrification and denitrification (Butterbach-Bahl et al., 2013) following N application to the crops and residue decomposition. In eastern Canada, where 90% of corn is produced, high N2O emissions episodes occur primarily following N fertilizer application in the fields (Grant and Pattey, 2003), and during spring thaw when soil moisture is high from snowmelt (Grant and Pattey, 1999). Enhanced efficiency fertilizers were developed in order to better match the release of the mineral fertilizer with the crop needs. The urease and nitrification inhibitors, are part of clean technologies that show potential to increase N use efficiency and reduce N2O emissions when combined together (Drury et al., 2017), as well as limiting ammonia volatilization. Preliminary results on commercial urease and nitrification inhibitors show their potential to mitigate N2O emissions.