N2o Emissions Related to Soil Nitrifying and Denitrifying Microbes Over a Growing Season with Corn (Zea mays L.) Biomass Removal.

Fluxes of N₂O from the soil surface diffused to the atmosphere are influenced by factors that affect microbial processes within the soil profile. These factors include soil temperature and available moisture, which have been shown to influence denitrification and a nitrous oxide flux from soil during freezing and thawing. For this reason, the timing of this study was during the spring thaw of 2010. Understanding how soil microorganism populations are controlled by crop production practices, such as biomass removal, provides greater insight into potential nutrient loss by denitrification and N₂O emissions. The objective of this study was to relate the timing of N₂O flux during a spring thaw event to the presence of active nitrifying and denitrifying microorganisms in soil with corn biomass harvested and returned. N₂O fluxes were measured half hourly using a tunable diode laser trace gas analyzer. Soil samples were collected every 24-48 hours over a two week period during the spring thaw event. From the soil samples, RNA/DNA was extracted and genes associated with nitrification and denitrification were quantified using Real Time-PCR. The previous fall, corn biomass was harvested as dry silage the first plot, and grain was harvested and the corn biomass was returned to the soil on the second plot. Both plots were conventionally tilled. Determining the abundance of soil nitrifying and denitrifying populations will help determine the short term impacts of corn biomass removal, on soil microbial activity, denitrification and N₂O emissions.