Nitrous oxide emissions from enhanced efficiency fertilizers in a rain-fed winter wheat cropping system in semi-arid southern Alberta
Haibo An1, Jennifer Owens, Brian Beres, Ramona Mohr, Xiying Hao. 2019. Nitrous oxide emissions from enhanced efficiency fertilizers in a rain-fed winter wheat cropping system in semi-arid southern Alberta. 2019 SSSA International Soils Meeting in San Diego, CA. Jan 5-9, 2019
Plain language summary
The overall benefit of enhanced efficiency fertilizers in reducing N2O emission is inconsistent for winter wheat production in a rain-fed cool semi-arid climate, but differences in fertilizer application timing appear to affect the efficiency differently depending on the fertilizers.
Enhanced efficiency fertilizers (EEFs) may reduce nitrous oxide (N2O) emissions and increase crop yields. Few studies have tested their ability to reduce N2O emissions in a cool, semi-arid rainfed climate. A three-year trial was conducted in Lethbridge, Alberta, Canada, to determine if manipulations to timing and placement of EEFs in a winter wheat system would impact N2O emissions. Four solid fertilizers were used: ESN (Environmentally Smart Nitrogen; polymer-coated urea), SuperU (urea with urease and nitrification inhibitor), Instinct (urea with nitrification inhibitor) and urea. Each fertilizer was applied using three application regimes: 100% applied at seeding, 30% applied at seeding and 70% late fall, and 30% applied at seeding and 70% at Feekes growth stage 5 (GS5). Nitrous oxide was measured weekly using static chambers and soil available N content was determined every one to two months. Over three years, the cumulative annual N2O emissions ranged from 0.08 to 2.3 kg N ha-1 (average 0.6 kg ha-1), from 0.05 to 48 g N kg-1 grain produced (average 0.15 g N kg-1 grain), while the emissions factors (EF) ranged from 0.01 to 1.36% (average 0.19%). When all fertilizer was applied at planting, the EF values were lowest from urea and highest from ESN two out of the three years. When fertilizer was split-applied as 70% late fall/30% at seeding, the EFs were lowest from ESN and highest from Instinct. When fertilizer was split-applied 30% at seeding/70% at GS5, the highest EF values were from urea and lower from ESN and Instinct. SuperU was not sensitive to application time. The overall benefit of EEF in reducing N2O emission is inconsistent for winter wheat production in a rain-fed cool semi-arid climate, but differences in fertilizer application timing appear to affect the EF differently depending on the EEF.