Agricultural system is the major source of greenhouse gas nitrous oxide (N₂O) emissions. Application of polymer-coated urea and urease and/or nitrification inhibitor has the potential in reducing soil N₂O emissions.

Drip irrigation is an effective water-saving strategy for crop production in arid regions. However, limited information is available on how fertilizer nitrogen (N) management affects soil N₂O emission under drip irrigation.

Researchers from the Xinjiang Institute of Ecology and Geography (XIEG) of the Chinese Academy of Sciences found that enhanced-efficiency nitrogen fertilizers were not effective in reducing N₂O emissions from drip-irrigated cotton field in arid northwest China.

They carried out a two-year cotton field experiment in Xinjiang to determine N₂O emissions from different fertilizer N sources (urea, polymer-coated urea-ESN, stabilized urea with nitrification and urease inhibitors-SuperU) and rates (120 and 240 kg N ha^-1).

Results showed that N₂O emissions over two-year growth season were significantly increased by 29-47% in treatment of ESN or SuperU, without significant effect on cotton yield. Reducing N rate by half significantly reduced both of the N₂O emissions and cotton yield.

The efficiency of ESN and SuperU is limited, and fertigation with urea at recommended rate is the best option to ensure cotton yield and mitigation in N₂O emission in this study site, according to the study.

The study was published in Science of The Total Environment.