Soil amendments reduce CH₄ and CO₂ but increase N₂O and NH₃ emissions in saline-alkali paddy fields

Limited research has been conducted on ammonia (NH₃) volatilization and greenhouse gases (GHGs) emissions in saline-alkali paddy fields, along with complex interaction involving various genes (16sRNA, amoA, narG, nirK, nosZ, and nifH). This study employed mesocosm-scale experiment to investigate NH₃ volatilization and GHGs emissions, focusing on bacterial communities and genic abundance, in saline-alkali paddy fields with desulfurized gypsum (DG) and organic fertilizer (OF) amendments. Compared to the control (CK) treatment, DG and OF treatments reduced methane (CH₄) and carbon dioxide (CO₂) emissions by 78.05 % and 26.18 %, and 65.84 % and 11.62 %, respectively. However, these treatments increased NH₃ volatilization by 26.26 % and 45.23 %, and nitrous oxide (N₂O) emission by 41.00 % and 12.31 %. Notably, NH₃ volatilization primarily stemmed from ammonia nitrogen (NH₄⁺-N), rather than total nitrogen (TN) in soil and water. N₂O was mainly produced from nitrate nitrogen (NO₃^--N) in soil and water, as well as NH₄⁺-N in water. The increase in NH₃ volatilization and N₂O emission in DG and OF treatments, was attributed to the reduced competition among bacterial communities, rather than the increased bacterial activity and genic copies. These findings offer valuable insights for managing nutrient loss and gaseous emissions in saline-alkali paddy fields.