N₂O emissions and source partitioning using stable isotopes under furrow and drip irrigation in vegetable field of...

N₂O emissions have increased significantly over the last decades, with much of the increase being ascribed to the expansion in agricultural land. Agricultural water management has significant influence on N₂O emissions, hence the investigation of N₂O emissions and the underlying production mechanisms under different irrigation managements would provide insights for N₂O emission reduction and rational water usage. Here, we used the stable isotope method to evaluate the N₂O isotopic signatures and the site preference, to clarify the N₂O emission dynamics and the N₂O source partitioning under different irrigation managements. We applied a furrow irrigation system and a drip irrigation system to maintain two different soil water conditions, allowance of dry-wet cycles and relatively stable water conditions, respectively. We found that the N₂O emission was significantly decreased under drip irrigation compared to furrow irrigation with cumulated N₂O flux of 526.3 mg m^-2 and 571.0 mg m^-2, respectively. In general, furrow irrigation with its dry-wet alternations promoted N₂O emissions, while drip irrigation created a relatively stable environment that reduced N₂O emissions. The intramolecular ¹⁵N isotopic composition of N₂O was used to partition the relative contribution of denitrification and nitrification. Nitrification dominated the processes driving N₂O production under both treatments, nearly accounting for 76% up to 100% during the initial N₂O peaks. Effective measure for mitigating N₂O emissions from the investigated vegetable field could be obtained by replacing the traditional furrow irrigation with drip irrigation.