Mitigating ammonia volatilization in rice cultivation: The impact of partial organic fertilizer substitution

Optimizing water and nitrogen management to minimize NH3 volatilization from paddy fields has been extensively studied. However, there is limited research on the combined effect of different rates of organic fertilizer substitution (OFS) and irrigation methods in rice cultivation, exploring an effective water and nitrogen combination is beneficial to mitigate NH3 volatilization. To address this gap, we conducted a two-year field experiment to investigate NH3 volatilization under different OFS rates (0%, 25%, and 50%) combined with continuous flooding irrigation (CF) and alternate wet and dry irrigation (AWD). Our findings revealed that NH3 fluxes exhibited similar emission patterns after each fertilization event and significantly decreased with increasing rates of OFS during the basal stage. Compared to no substitution (ON0), the low (ON25) and high (ON50) rates of OFS reduced cumulative NH3 emissions by 18.9% and 16.6%, and lowed NH3 emission factors (EFs) by 26.7% and 23.3%, respectively. Although OFS resulted in a slight reduction in rice yield, yield-scaled NH3 emissions were significantly reduced by 11.9% and 6.5% under the low and high substitution rates, respectively. This reduction was mainly attributed to the slight yield reduction observed at the low substitution rate. Furthermore, when combined with ON0, AWD irrigation had the potential to increase NH3 volatilization. However, this increase was not observed when combined with ON25 and ON50. During each fertilization stage, floodwater + concentration emerged as the prominent environmental factor influencing NH3 volatilization, showing a stronger and more positive correlation compared to other factors such as floodwater pH, soil pH, and NH4+ concentration. Based on our findings, we recommend implementing effective water and nitrogen management strategies to minimize NH3 volatilization in rice cultivation. This involves applying a lower rate of organic fertilizer substitution during the basal stage, maintaining high water levels during fertilization, and implementing mild AWD irrigation during non-fertilization periods. [Display omitted] •Effectively water and nitrogen management for NH3 volatilization reduction was explored.•NH3 volatilization reduction of organic fertilizer substitution (OFS) focused during basal stage.•AWD irrigation showed the equal NH3 volatilization reduction with CF when combined with organic fertilizer while a potential increase with inorganic fertilizer.•Floodwater NH4+ co