Evaluation of 4R Nitrogen Management Practices on N2O Emisisons from Irrigated Processing Potato in Manitoba.

The effect of nitrogen (N) fertilizer practices, including rate, source and placement on nitrous oxide (N₂O) emissions from soil is not well understood. The impact of irrigation in N₂O emissions from Canadian cropland is also poorly understood. This study determined N₂O emissions for some options for growers to management synthetic N fertilizer use in irrigated potato, cv Russet Burbank used for processing, in Manitoba. The study was conducted at the Canada Manitoba Crop Diversification Centre near Carberry, MB in 2011 and 2012. It considered factorial treatments of N rate (100, 200 kg N ha^-1), placement (banding, broadcast incorporated) and source (urea, ESN). Nitrous oxide emissions were monitored using static-vented chambers. Nitrous oxide emissions occurred when soil volumetric moisture content was above 20% and shortly after N additions with planting in both years. The post-planting period of 2011 was wetter than that for 2012 with Banding having reduced emissions compared to Broadcast incorporated treatments at this time in 2011 but not 2012. In 2012, soil moisture was higher mid-season in which emissions with Banding treatments were greater than with Broadcast incorporated treatments. Over both years, Banding emissions were 3.47 kg N₂O-N ha^-1 while broadcast emissions were 3.37 kg N₂O-N ha^-1. Emissions were linked with rainfall events shortly after planting, but not with irrigation events. Emissions from ESN treatments were 4.53 kg N₂O-N ha^-1 compared to 2.31 kg N₂O-N ha^-1 over both years. Higher fertilizer rates induced higher emissions in both years, 3.70 k g N₂O-N ha^-1 at 200 kg N ha^-1 and 3.14 kg N₂O-N ha^-1 from 100 kg N ha^-1 in N Placement. Results will also be discussed in terms of yield intensity emissions.