Winter wheat responses to enhanced efficiency granular nitrogen fertilizer in the Canadian Prairies

Abstract

Optimizing the timing of nitrogen (N) enhanced efficiency fertilizers (EEFs) may maximize winter wheat (Triticum aestivum L.) grain yield, protein content, and N-use efficiency (NUE). From 2013 to 2018, experiments were conducted at two irrigated and six rain-fed sites across the Canadian Prairies (24 site-years) to evaluate winter wheat responses to N source and timing/placement effects of EEFs. Nitrogen sources included untreated urea, nitrification inhibitor nitrapyrin treated urea (Nitrapyrin), urease inhibitor N-(n-butyl) thiophosphoric triamide (NBPT) plus nitrification inhibitor dicyandiamide (DCD) treated urea (NBPT+DCD), and polymer-coated urea (PCU). The N sources were all side-banded at planting, 30% side-banded at planting plus 70% broadcast in-crop late-fall (averaged 38 days after planting; split-applied late-fall) or 30% side-banded at planting plus 70% broadcast in-crop early-spring (averaged 224 days after planting; split-applied early-spring). Nitrous oxide and methane emissions were measured at one rain-fed site to test whether N source and timing/placement influenced CO2-equivalents (CO2-eq; nitrous oxide+methane). Under irrigation, NBPT+DCD consistently produced the highest yields regardless of timing/placement; however, the 80% of recommended rate caused sub-optimal protein responses (≤11%) unless split-application of N was adopted. . Untreated urea produced the highest net CO2-eq and yield-scaled CO2-eq emissions, with the highest emissions when urea was split-applied early-spring. To optimize winter wheat production and NUE, we conclude that NBPT+DCD all-banded during seeding operations or split-applied early-spring provided similar and often superior results than other sources including a more typical system of urea side-banded at the time of seeding.

Complete Issue

“…Nitrification inhibitors have highly variable impacts on nitrate leaching but may reduce N 2 O emissions from denitrification and nitrification by approximately 35% (Ruser & Schulz, 2015;Woodward et al 2021). Soil N 2 O emissions are lower under the semiarid conditions of western Canada than in more humid regions, and inhibitors have provided inconsistent reductions in N 2 O emissions to date (Thilakarathna et al, 2020;Wang et al, 2023). Another reason for the limited impact of inhibitors in these studies is that the supply of N from soil accounts for 50% or more of the N acquired by crops but is negligibly impacted by the addition of inhibitors.…”

Evaluation of Urease and Nitrification Inhibitors in Western Canada

“…Nitrification inhibitors have highly variable impacts on nitrate leaching but may reduce N 2 O emissions from denitrification and nitrification by approximately 35% (Ruser & Schulz, 2015;Woodward et al 2021). Soil N 2 O emissions are lower under the semiarid conditions of western Canada than in more humid regions, and inhibitors have provided inconsistent reductions in N 2 O emissions to date (Thilakarathna et al, 2020;Wang et al, 2023). Another reason for the limited impact of inhibitors in these studies is that the supply of N from soil accounts for 50% or more of the N acquired by crops but is negligibly impacted by the addition of inhibitors.…”

Cropping system adaptation for enhanced resilience to climate change in cold climate regions

“…Including perennial forages, as seed crops, in crop rotations is an option for greater cropping system resiliency in cold climate agricultural regions (Khanal 2023), while drought-resistant cover crops also offer additional opportunities for maintaining soil cover and fertility in dryland agriculture (Ben Kalifa et al 2023). Soil fertility in potato (Solanum tuberosum L.) production systems was improved through the application of woody mulch (Nyiraneza et al 2023), whereas judicious use of nitrogen fertilizers improved the yield of spring and winter wheat (Biswas et al 2023;Owens et al 2023;Wang et al 2023).…”