Liming-Induced Nitrous Oxide Emissions from Acidic Soils Dominated by Stimulative Nitrification

Area of Science:

• Agricultural Science
• Environmental Science
• Soil Science

Background:

• Nitrous oxide (N₂O) is a potent greenhouse gas primarily emitted from agricultural soils.
• Acidic soils are particularly susceptible to N₂O emissions driven by nitrification.
• Alkaline amendments are used to counteract soil acidification.

Purpose of the Study:

• To investigate the impact of alkaline mineral amendments on N₂O emissions in acidic soils.
• To determine the effects on nitrification rates and key functional genes.
• To understand the mechanisms linking soil pH, nitrification, and N₂O production.

Main Methods:

• Utilized a robotic automated incubation system for controlled soil experiments.
• Applied a calcium silicate mineral product (CSMP) alone and with urea to two acidic soils.
• Measured N₂O emissions, nitrification rates, and abundance of ammonia-oxidizing bacteria (AOB) and archaea (AOA) genes (amoA).

Main Results:

• CSMP treatment alone increased N₂O emissions 18.4-fold in acidic soils.
• Combined urea and CSMP (U + CSMP) treatment resulted in a 61.6-fold increase in N₂O emissions.
• Increased pH led to higher AOB-amoA abundance and decreased AOA-amoA abundance, driving N₂O emissions.

Conclusions:

• Alkaline amendments like CSMP can significantly enhance N₂O emissions from acidic soils by stimulating nitrification.
• Careful management of CSMP is necessary to prevent unintended increases in greenhouse gas emissions.
• Future strategies should integrate CSMP with nitrification mitigation approaches for sustainable soil management and climate change mitigation.