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This research investigates how soil salinization impacts nitrogen emissions and the effectiveness of nitrogen stabilizers.

March 26, 2026Open Access

Soil salinization stimulated reactive N emissions and differentially affects the efficacy of N stabilizers

Key Points

This research investigates how soil salinization impacts nitrogen emissions and the effectiveness of nitrogen stabilizers.
Conducted microcosm aerobiotic incubation experiments with salt addition and N stabilizer amendment.
Measured emissions of NH3, N2O, NO, and CO2 from different treatments.
Used quantitative PCR and metagenomic analysis to assess microbial community shifts.
Compared the effects of nitrification inhibitors, urease inhibitors, and double inhibitors on nitrogen emissions.
Salinization increased NH3, N2O, and NO emissions by 68.3%, 41.3%, and 45.3%, respectively.
Nitrification inhibitors reduced N2O and NO emissions by over 60% but were less effective under salinization.
Urease inhibitors retained N in urea form, reducing reactive N gas emissions.
Salinization amplified ammonia-oxidizing bacteria and increased NH3 emissions under nitrification inhibitor treatments.

Abstract

Soil salinization profoundly affects soil nitrogen (N) transformation and reactive N loss. Although N stabilizers, such as urease/nitrification inhibitors, are promising tools for mitigating N pollution and enhancing nutrient efficiency, their response to soil salinization is unclear. A microcosm aerobiotic incubation experiment was conducted to investigate the effects of salinization (salt addition) combined with N stabilizer amendment on soil NH 3 , N 2 O, NO, and CO 2 emissions. Additionally, quantitative PCR was combined with metagenomic analysis to identify microbial community shifts and functional gene responses. The results showed that urea with salt addition (SU) increased soil NH 3 , N 2 O, and NO emissions by 68.3%, 41.3%, and 45.3%, respectively, compared with urea alone, owing to the rapid growth of ammonia-oxidizing bacteria (AOB) carrying amo A genes and increased nitrite accumulation. Nitrification inhibitor (NI) amendment reduced N 2 O and NO emissions by over 60% compared with the corresponding U and SU treatments, although this amendment increased NH 3 volatilization. Soil salinization combined with NI increased NH 3 , N 2 O, and NO emissions by 55.7%, 22.7%, and 43.6%, respectively, compared with those observed under NI without salinization; this was a direct result of Nitrosospira amplification (gene abundance). Urease inhibitor (UI) or double inhibitor (DI) amendment retained N in the form of urea, thereby reducing substrate availability for reactive N gas emissions by lowering the number of amo A-AOB gene copies and reducing the abundances of the dominant genera. Furthermore, salt addition did not affect the efficacy of UI or DI. These findings suggest that the application of UIs could be prioritized for soils with high pH and salinity levels to reduce N pollution and prolong soil N availability for crops. • Soil salinization increased soil NH 3 , N 2 O, and NO emissions. • Increased ammonia-oxidizing bacteria abundance and nitrite under salt addition. • Nitrification inhibitor reduced N 2 O and NO emissions, but degraded by salinization. • Urease and double inhibitors retained fertilizer-N as urea and reduced N losses.

Soil salinization stimulated reactive N emissions and differentially affects the efficacy of N stabilizers

Key Points

Abstract

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