Effects of fertilizer rate on yield-scaled nitrous oxide emissions from two soil types

Abstract

Synthetic N fertilizer application has increased crop yields to meet the growing food demand, but it has also contributed to greater N₂O emissions from cultivated fields. Best management practices, including the 4Rs (right source, right rate, right time, and right place) of nutrient management, have been proposed to mitigate these emissions; however, there have been inconsistent results regarding the impact of soil texture on yield-scaled N₂O emissions. To clarify this issue, a field study was undertaken to evaluate the influence of three nitrogen fertilization rates (140, 180, and 220 kg N ha⁻¹) on N₂O emissions and grain corn (Zea mays L.) yield from sandy loam and silty clay soil field sites situated in southwestern Quebec, Canada. Crop nitrogen uptake and yields were greater on the sandy loam than on the silty clay. Grain yields increased with N fertilization rate. Cumulative N₂O emissions from the sandy loam soil were up to threefold greater than those from the silty clay soil due to soil and weather conditions during fertilizer application. No significant differences were found in the N₂O fluxes among the N rate treatments in either soil. Assessing results from five other studies, we found that under corn production, overall yield-scaled emissions from poorly drained soils were fivefold greater than well-drained (coarse- and medium-textured) soils. However, yield-scaled emissions vary more widely in poorly drained soils, showing both lower and higher values than in well-drained soils. These results demonstrate the need to consider soil textural differences and the impacts of climate variability on emissions when recommending fertilizer rates to reduce N₂O emissions.