Nitrogen stabilizers to enhance nitrogen use efficiency and reduce greenhouse gas emissions

The use of stabilized and enhanced efficiency forms of N fertilizer has potential to reduce unwanted losses of applied N fertilizer through ammonia volatilization, leaching, and or denitrification. The main objective of this project is to assess the effect of various commercially available forms of stabilized N on nitrous oxide (N₂O) emissions, leaching, nutrient use efficiency (NUE), and crop yield response in cereal crops. The experiments use a factorial set of treatments involving form of N, timing of application, and rate of N application. Nitrogen forms include untreated urea, urea treated with both a nitrification and urease inhibitor (Super U®), a urea treated with a nitrification inhibitor only (eNtrench®), and a polymer-coated, controlled-release urea (ESN®). Application was 0, 50, 100, and 150% of the local recommended fertilization rates for wheat, specifically 0, 40, 80, and 120 kg N/ha. Timing includes fall banded, and pre-plant spring banded. Identical experiments are being conducted at two sites, differing in geography and climate (Ellerslie research farm near Edmonton, Alberta on a Black soil; and the Lethbridge Research Station, near Lethbridge, Alberta, on a Dark Brown soil.

Field N₂O flux measurements using the non-steady state chamber method will be carried out. Wheat will be seeded after spring banding of fertilizer. For both fall and spring-banded treatments, soil samples (0 to 30, 30 to 60 cm) will be taken before spring banding and at the tillering (5-leaf) stage. The fall treatments were applied in October 2015 and N₂O fluxes were measured, but gas flux were very low on all fall treatments because of low moisture received in the fall up to freezing of soils. The measurement of N₂O fluxes will resume in the early spring after the soil thaws on the fall treatments, and on the spring treatments right after fertilizing and planting. It is planned to conduct these experiments for two growing seasons.