Denitrification in suburban lawn soils.

Area of Science:

• Environmental Science
• Soil Science
• Ecology

Background:

• Nitrogen (N) is frequently added to urban and suburban lawns, but its fate remains uncertain.
• Understanding N cycling in residential landscapes is crucial for managing nutrient pollution and greenhouse gas emissions.

Purpose of the Study:

• To quantify nitrogen (N) and nitrous oxide (NO) fluxes from lawns.
• To identify key environmental factors controlling denitrification and NO production in lawn soils.

Main Methods:

• Direct flux and in situ chamber methods were used to measure N and NO fluxes.
• Soil oxygen, moisture, and available NO were monitored using sensors.
• Laboratory incubations assessed NO production and consumption under controlled conditions.

Main Results:

• Denitrification rates were high only in saturated, fertilized soils, totaling 14.0 ± 3.6 kg N ha⁻¹ yr⁻¹.
• Over 80% of annual denitrification occurred during just 5% of the growing season.
• In situ NO fluxes were low, but laboratory incubations revealed high initial NO production in saturated, fertilized soils, followed by consumption.

Conclusions:

• Denitrification is an important N removal pathway in lawns but is highly dependent on soil saturation and fertilization.
• Lawns can be a significant source of NO due to a lag between production and consumption, especially after fertilization and saturation.