Fertilizer-N management and nitrous oxide emissions from four sites in Saskatchewan

Abstract

Nitrous oxide (N2O) is a powerful greenhouse gas that also depletes stratospheric ozone. The use of fertilizer-N for agricultural purposes is thought to contribute significantly to Canadian anthropogenic N2O emissions. However, the influence of fertilizer-N form, placement, rates of application, and their interaction with soil and climate is not well understood. We report on a 3-year project that compared N2O emissions from four locations with contrasting soil and climatic conditions in Saskatchewan. Spring wheat was fertilized with urea and anhydrous ammonia (AA) banded in the fall, or in mid-row and side-row positions at seeding time in the spring. N2O emissions were similar from AA compared to urea. Emissions tended to be higher when fertilizer-N was placed in a mid-row compared to side-row banded position. Within the range of rates applied in this study, N2O emissions increased linearly with fertilizer-N rate. The percentage of fertilizer-N lost as N2O calculated from our data ranged from near zero (in drought conditions) to 1.0 %. Most values fell at or below 0.4 % with an overall mean of 0.2 %.