Nitrogen Fertilization of Lawns Enhanced Soil Nitrous Oxide Emissions by Increasing Autotrophic Nitrification

Abstract

As nitrous oxide (N2O) is one of the most important greenhouse gases, N2O emission pathways and regulation techniques in soils with different vegetation types have become a research focus. Currently, a diverse array of research exists on the N2O emissions from soils of different vegetation types, e.g., forest, grassland, and agriculture. Few studies have investigated the microbial processes of N2O emissions from lawn soils. Fertilization levels in lawn soils are often similar to or much higher than those in agricultural ecosystems, thus fertilized lawn is an important source of atmospheric N2O. In the study, we employed the 15N-nitrate labelling method combined with the nitrification inhibition technique to distinguish microbial processes and their contribution to N2O emissions in long-term nitrogen fertilised lawns. We found that the N2O emission rate from the control treatment was 1.0 nmol g−1 h−1 over the incubation, with autotrophic nitrification contributing 60%. The N2O emission rate increased to 1.4 nmol g−1 h−1 from the soil treated with long-term N fertilization, and the contribution of autotrophic nitrification increased to 69%. N fertilization did not significantly increase the contribution of denitrification (24–26%) in the total N2O emissions. However, N fertilization substantially decreased the contribution of heterotrophic nitrification from 13 to 0.4% in the total N2O emissions. Co-denitrification to N2O was detected but the overall contribution was of minor importance (3–5%). The correlation analysis revealed that soil NO3− levels were the main influencing factors in the N2O producing microbial processes. Our results suggest that N fertilization altered both N2O production rates and the contribution pattern of microbial processes, and indicate the autotrophic nitrification and heterotrophic nitrification are more sensitive to N fertilization than denitrification and co-denitrification.

Full substitution of chemical fertilizer by organic manure decreases soil N2O emissions driven by ammonia oxidizers and gross nitrogen transformations

“…After organic or chemical fertilizer application, the contribution of autotrophic nitrification to N 2 O emissions increased from 60% to 69%, while the contribution of heterotrophic nitrification to N 2 O emissions decreased from 13% to 0.4% in a previous study (Xun et al, 2022).…”

“…In Cambisol soils of the North China Plain, autotrophic nitrification, rather than heterotrophic nitrification, was found to be the dominate pathway for the N 2 O emissions (Zhang et al, 2023; Zhu et al, 2019). After organic or chemical fertilizer application, the contribution of autotrophic nitrification to N 2 O emissions increased from 60% to 69%, while the contribution of heterotrophic nitrification to N 2 O emissions decreased from 13% to 0.4% in a previous study (Xun et al, 2022).…”

Nitrogen removal performance of improved subsurface wastewater infiltration system under various influent carbon–nitrogen ratios

“…Using the gas‐layered collector, N 2 O emissions in the upper (40 cm), middle (80 cm), and lower (120 cm) layers were determined simultaneously. N 2 O can be produced as a chemical byproduct of nitrification and an intermediate product of denitrification in SWIS (Xun et al, 2022). The level of DO determines the processes that dominate N transformation processes at different soil depths (Su et al, 2023).…”

“…N 2 O is the intermediate product of the denitrification catalyzed by the nitric oxide reductase (qnorB), which is then converted to N 2 by the nosZ (Yao et al, 2023; Zhang et al, 2023). Therefore, the N 2 O conversion rate tends to be lower under higher nosZ activity than under the low nosZ condition in SWIS, indicating that the denitrification reaction was complete (Xun et al, 2022). In this study, the gene expression of nosZ increased and remained relatively high level after the addition of the amended soil matrix (Figure 5i), which effectively controlled the emission of N 2 O.…”

“…As a bias of wastewater treatment, SWIS has been proven to be a source of greenhouse gas nitrous oxide (Li et al, 2019; Pang et al, 2020). Increasing the conversion of nitrous oxide (N 2 O) to inert dinitrogen (N 2 ) form is an effective method for mitigating global warming and ozone depletion (Xun et al, 2022). The emission of N 2 O and the removal of N pollutants are regulated by multiple microbial functional genes (Pan et al, 2017; Sun et al, 2018).…”