Biotic and Abiotic Factors Controlling Nitrous Oxide Emissions From An Agricultural Soil.

Nitrous oxide is a greenhouse gas 300 times more potent than carbon dioxide at trapping heat.  Atmospheric levels have been steadily rising over the past 30 years, with agricultural soil management the major anthropogenic contributor in the United States.  Studies have measured periodic nitrous oxide emissions from fields, but factors controlling the timing and amounts of emissions remain obscure.  In our studies, novel plant growth systems held in controlled environment chambers were used to precisely control the aerial and soil environments.  It was possible to determine time lines of nitrous oxide release from soils after adjustments in fertilization and soil water status. Soil drying periods and the presence of plants were required for maximal nitrous oxide release. Bursts generally occurred about 6-8 hrs after fertilizer and water were added to the system. Experiments are continuing to explore the physiological basis for plants’ role in the response.