Nitrous oxide emissions with enhanced efficiency and conventional urea fertilizers in winter wheat
An, H., J. Owens, B. Beres, Y. Li and X. Hao. 2021.
Abstract
Optimizing nitrogen fertilizer manage-
ment can reduce nitrous oxide (N2O) emissions. This
study tested if split applying enhanced efficiency
fertilizers (EEFs) resulted in lower N2O emissions
than applying equivalent rates of urea at planting. In
semiarid southern Alberta, field trials were conducted
during three years (planting to harvest) in rainfed
winter wheat crops. Annual fertilizer rates ranged
from 146 to 176 kg N ha-1. Fertilizer types were urea,
and three EEFs (polymer-coated urea, urea with urease
and nitrification inhibitors, and urea with a nitrifica-
tion inhibitor). Each fertilizer type was applied three
ways: 100% banded at planting, split applied 30%
banded at planting and 70% broadcast in late fall, and
split applied 30% banded at planting and 70%
broadcast at Feekes growth stage 4 (GS4, post-tiller
formation, wheat entering the greening up phase in the
early spring). Nitrous oxide was measured using static
chambers between sub-weekly and monthly from planting to harvest. Over three years, cumulative N2O
emissions ranged from 0.16 to 1.32 kg N ha-1.This
was equivalent to emissions factors between 0.009 and
0.688%. Cumulative N2O emissions and emissions
factors did not differ between fertilizer types, but they
were lower when fertilizer was split applied at GS4
compared to in late fall (0.10 ≥ P ). Our study suggests
that EEFs do not reduce N2O emissions from rainfed
winter wheat crops, but a well-timed split application
with a majority of fertilizer applied after winter can
minimize N2O emissions.
Key Words
Nitrogen fertilizer, Nitrification inhibitor, Polymer-coated urea, Urease inhibitor
