Legacy effects cause systematic underestimation of N<sub>2</sub>O emission factors.
basic_science · Level V
Where this comes from
- Record sourced from PubMed, PMID 40113803.
- Also identified by DOI 10.1038/s41467-025-58090-0 and PMC identifier 11926090.
- Licence recorded as CC BY-NC-ND.
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Abstract
Agricultural soils contribute ~52% of global anthropogenic nitrous oxide (N<sub>2</sub>O) emissions, predominantly from nitrogen (N) fertilizer use. Global N<sub>2</sub>O emission factors (EFs), estimated using IPCC Tier 1 methodologies, largely rely on short-term field measurements that ignore legacy effects of historic N fertilization. Here we show, through data synthesis and experiments, that EFs increase over time. Historic N addition increases soil N availability, lowers soil pH, and stimulates the abundance of N<sub>2</sub>O producing microorganisms and N<sub>2</sub>O emissions in control plots, causing underestimates of EFs in short-term experiments. Accounting for this legacy effect, we estimate that global EFs and annual fertilizer-induced N<sub>2</sub>O emissions of cropland are 1.9% and 2.1 Tg N<sub>2</sub>O-N yr<sup>-1</sup>, respectively, both ~110% higher than IPCC estimates. Our findings highlight the significance of legacy effects on N<sub>2</sub>O emissions, emphasize the importance of long-term experiments for accurate N<sub>2</sub>O emission estimates, and underscore the need for mitigation practices to reduce N<sub>2</sub>O emissions.