Nutrient Management Research Database

Urea placement in band or nests has been shown to enhance N use efficiency, but limited work has been done to assess its affect on N₂O emissions. This study compared N₂O emissions from urea prills applied to an Amsterdam silt loam (fine-silty, mixed, superactive, frigid Typic Haplustolls) using broadcast, band, and nest placements. Experiments were conducted in greenhouse pots (200 kg N ha⁻¹) and in canola (Brassica rapa L.) seeded fields using rates of 100 kg N ha⁻¹ (recommended) and 200 kg N ha⁻¹ Urea placement affected N₂O emission patterns and cumulative N₂O losses in the greenhouse and field. Urea prills placed in nests, and sometimes bands delayed N₂O production with peak flux activity occurring later, and elevated emission activity being more prolonged than for broadcast applications. Differences were more obvious at 200 kg N ha⁻¹ These effects were attributed to a delay in urea hydrolysis and inhibition of nitrification. The fraction of applied urea-N lost as N₂O for broadcast, band, and nest placements applied at the recommended rate averaged 2.0, 2.7, and 5.8 g N kg⁻¹ N, respectively. The fraction of applied urea-N lost as N₂O averaged 2.9, 10.4, and 9.2 g N kg⁻¹ N for broadcast, band, and nest placements when urea-N rate was increased from 100 to 200 kg N ha⁻¹, respectively. Greater N₂O production with nest placement may in part be due to significant soil NO₂–N accumulations. Potential benefits to crop fertilizer use efficiency that come with placement of urea in concentrated zones may lead to enhanced N₂O production.

This study examined the effects of two applications rates (90 and 180 lbs N/ac) of urea on nitrous oxide emissions in a no-tilled canola cropping system.

Urea was applied as surface broadcast, band, or nest placements.

Measurements taken include N2O emissions, water, and nitrogen.

N2O emissions for the unfertilized treatments were consistently low, with precipitation being the primary driver of emissions.

The 90 lbs N/ac urea application increased N2O emissions, though patterns differed based on application method. At 90 lbs N/ac, emissions were highest in nest, following by band, followed by broadcast. At 180 lbs N/ac, band was the highest, followed by nest and then broadcast.

Soil ammonium levels were greatest in nest, followed by band, and broadcast were lowest. Higher levels of N fertilization resulted in elevated levels of ammonium.

Yields were greater for nest and band treatments.

It is important to consider yields increases that result from banding and nest applications, despite the fact that these techniques resulted in increased emissions.