Temporal Variations in N2O Emissions in Maize and Wheat Crop Seasons: Impact of N-Fertilization, Crop Growth, and Weather Variables

Abstract

ABSTRACTNitrous oxide (N2O) emission from agricultural soils is one of the important contributors to global greenhouse gas (GHG) emissions. The impact of crop growth and weather variables on N2O emissions during maize (Zea mays L.) and wheat (Triticumaestivum L.) crop seasons in unfertilized soils (TC) and N (nitrogen) fertilized soils (TN) was studied in a field experiment in Punjab, India. The fluxes were measured via closed chambers and a gas chromatography. In the maize crop season, N2O fluxes in TC ranged from 11.1 to 61.2 N2O-N g ha−1day−1, and in TN ranged from 10.3 to 129.2 N2O-N g ha−1day−1, respectively, whereas in the wheat crop season fluxes were comparatively lower, and they ranged from 3.3 to 21.2 N2O-N g ha−1day−1 in TC and from 4.8 to 44.4 N2O-N g ha−1day−1 in TN. More than 60% of total season emissions occurred during vegetative growth stages of both the crops. N2O fluxes in both crop seasons were mainly controlled by rainfall, but the impact was marked in the maize season. Additionally, the impact of fertilizer-N application on N2O fluxes was also evident as in TN the influence of weather variables on fluxes was less by 40% than in TC. The study suggested that N2O emissions could be large during vegetative growth stages if rainfall or irrigation events coincide with N-fertilization.