Effects of nitrogen and water addition on N2O emissions in temperate grasslands, northern China

Soil organic matter on arid saline-alkali land drives greenhouse gas emissions from artificial and natural grasslands in different directions

“…Castaldi (2000) found that cropland N 2 O mainly originated from denitrification and was more sensitive to temperature compared to forests (Castaldi, 2000). For grasslands, soil rewetting and water-holding capacity influenced the source and yield of N 2 O, with soil moisture having a greater impact than temperature during the growing season (Du et al, 2006;Liu et al, 2012;Liu et al, 2018;Guo et al, 2022;Yu et al, 2022;Guo et al, 2023). Our results showed similar patterns.…”

The Seasonal Response of N2O Emissions to Increasing Precipitation and Nitrogen Deposition and Its Driving Factors in Temperate Semi-Arid Grassland

“…The trade-off of the opposite effects resulted in an approximately 2.54 mg N 2 O m −2 increase in seasonal cumulative emissions. The effect of water addition on N 2 O emissions was not consistent for different N application levels, but the interactive effects were not significant, which was different from the previous year [9]. It indicated a changed sensitivity of water addition under N amendment, though the WFPS condition and MBC content were not significantly changed.…”

“…The cumulative N 2 O emissions increased linearly with the N application rate with an average of 0.79 mg N 2 O g −1 N. This trend was equivalent to an EF of 0.06%, which is much lower than the default value (0.5%) for an arid environment according to the IPCC [1]. These increased cumulative N 2 O emissions were dominated by the N 2 O pulses during July and August after N amendment, as with the management-driven hot moment of N 2 O fluxes previously reported [37,38], which was evidenced by the importance of the direct effect of N addition in the SEM, but the temporal variations after N addition were not as significant as in previous years [9,26]. The reduced temporal variations might result from the weaker disturbance due to accumulated NO 3 − legacy after 5 years' treatment [39,40].…”

“…Global scale meta-analyses showed that the averaged Agronomy 2024, 14, 1153 2 of 14 N 2 O emissions with N-fertilization was 5.16-fold that without additional N in grasslands [7]. The observation from previous growing seasons reported a linear correlation between N 2 O emissions and N application rates [9], though it was below the default N 2 O emission factor (EF, 0.5-1.6%) according to the IPCC [10]. The positive effects of increased N deposition on soil N 2 O emissions was suggested to result from the accelerated N cycling process.…”

“…Rewetting was widely agreed to be one of the hot moments for microbial-driven N 2 O emissions, since water supply was one predominant factor for microbial activities [11,12]. Moreover, increased water would lift the availability of soil nutrients and activity of microorganisms, resulting in higher sensitivity of N 2 O emissions to additional N [9,16]. These results suggested a high risk of N 2 O emissions increasing during growing season under global change.…”