Are annual nitrous oxide fluxes sensitive to warming and increasing precipitation in the Gurbantunggut Desert?

Abstract

Temperate desert soils are an important source of atmospheric nitrous oxide (N2O). However, it is uncertain how N2O emissions respond to warming, increased rainfall and nitrogen (N) addition in such soils. A multifactorial field manipulation study was carried out in the Gurbantunggut Desert, China's second largest desert, to investigate how these factors influence desert soil N2O emissions and to assess inter‐year variation. In our 3‐year study, under current climatic conditions, the annual flux of N2O in this temperate desert soil was 0.13 ± 0.02 kg N ha−1 yr−1, with the period of no plant growth contributing 43% of the annual emission. Surprisingly, there was no significant change in annual N2O flux under warming (+1°C) or increased precipitation (30%, +60 mm yr−1). In contrast, N2O emissions were significantly affected by extreme drought followed by precipitation. Additional N input, at 30 or 60 kg N ha−1 yr−1, greatly elevated annual N2O emission by 55–133%. The combined impact of N deposition and increasing rainfall on N2O emission was greater than that of any single factor, except for N deposition. This suggests that N2O emissions in this desert are driven primarily by soil available N content and are less sensitive to variations in soil temperature and moisture.

No significant change noted in annual nitrous oxide flux under precipitation changes in a temperate desert steppe

“…This can be attributed to the following factors: The precipitation change did not significantly change the abundance of key functional microorganisms in the nitrification and denitrification processes (Figure 1), and increasing the precipitation during this period of precipitation concentration enhanced the soil's anaerobic environment, increased the total denitrification rate, and promoted the generation of N 2 O to be converted into nitrogen; accordingly, no significant changes occurred in the N 2 O emissions (Barnard et al, 2005). In addition, the precipitation changes had no significant effect on N 2 O emissions in the nongrowing season (Figures 2 and 3), which is consistent with the results of previous research (Yue, Cui, et al, 2021). This is attributed mainly to the limitations of insufficient precipitation and excessively low soil temperature in the nongrowing season (Figure 2a).…”

“…The results of the 2‐year study showed that N 2 O emission is relatively low in the desert steppe, at −0.04 to +15.0 μg N m −2 hr −1 (Figure 2). Although this range is consistent with that reported previously for grassland, desert, and north Australian savanna soils (W. W. Chen et al, 2013; Grover et al, 2012; Yue, Cui, et al, 2021), it is significantly lower than that of agricultural soil (C. Liu et al, 2012). An interesting result of the present study is that N 2 O was occasionally absorbed by the soil, particularly when the precipitation was reduced 60% (Figure 2).…”

“…In addition, the composition and richness of plant species as well as net primary productivity and soil nutrients are significantly affected by precipitation changes in arid regions (Mooshammer et al, 2017; Zuo et al, 2020). Some studies have shown that plant species diversity, biomass, and functional traits in addition to the available carbon and nitrogen in the soil significantly affect N 2 O emissions (Abalos et al, 2018; Niklaus et al, 2016; Subbarao et al, 2015; Yue, Cui, et al, 2021). However, the response of N 2 O emissions to precipitation changes in desert steppe environments and the driving mechanism remain unclear.…”

“…Therefore, these processes are highly sensitive to changes in precipitation (Brown et al, 2011). In desert soil, however, no significant impact on the annual N 2 O flux was observed when the precipitation was increased 30% (Yue, Cui, et al, 2021). Moreover, a small amount of precipitation (5 mm) has been shown to occasionally boost N 2 O emissions owing mainly to the limitations of the soil NH 4 + ‐N content (Yue, Zuo, et al, 2021).…”

“…It is widely accepted that soil NH 4 + ‐N and NO 3 − ‐N are the substrates of soil nitrification and denitrification processes (Barnard et al, 2005; Gu et al, 2019). Some studies have also shown that N 2 O emissions are significantly increased by the addition of nitrogen (Gu et al, 2019; Yue, Cui, et al, 2021; Zhou et al, 2019). Other research has shown that N 2 O emissions in a typical temperate steppe environment can be enhanced significantly by increasing the precipitation.…”