Nitrous Oxide Emissions From Canola Fields with ESN Fertilizer Application.

ABSTRACT

Environmentally Smart Nitrogen (ESN, polymer coated urea) has the potential to reduce N₂O emissions. Our study investigated N₂O emissions from canola production on three different soil types receiving urea or ESN fertilizer. Canola (Brassica napus L.) was grown in rotation with barley (Hordeum vulgare L.) from 2005 to 2008 on a Grey Luvisol (Haplocryalf) at Beaverlodge, a Black Chernozem (Haplocryoll) at Lacombe and a Dark Brown Chernozem (Haplustoll) at Lethbridge. Urea and ESN were applied at 1 and 1.5 times (x) the recommended agronomic rate. The N₂O emissions were measured using vented static chambers bi-weekly during the growing season from 2005 to 2008 at Lethbridge and from 2006 to 2008 at Lacombe and Beaverlodge. N₂O emissions from canola fields varied considerably (0.11 to 4.44 kg N ha^-1 yr^-1) during the growing season across all three soil types. When applied at the recommended agronomic rate, average N₂O emissions from ESN treatments across the whole experimental period were 78% (P=0.08), 110% (P=0.65) and 64% (P=0.04) of values from urea treatments for Grey Luvisol, Black Chernozem and Dark Brown Chernozem, respectively. When ESN was applied at 1.5 x the agronomic rate, N₂O emissions were 582% (P=0.04), 93% (P=0.76) and 145% (P=0.31) of values from ESN applied at its recommended agronomic rate, for the three corresponding soils. Our study suggests that N₂O emission could be reduced using ESN, compared to urea. However, the reduction potential depends on soil type (location). Applying ESN at higher than the recommended agronomic rate should be avoided, particularly to Grey Luvisol where the increases in N₂O emissions were far greater with higher fertilizer application rates.