68-17 Continuous Monitoring of Nitrous Oxide from Agricultural Field: New Data on Temperature and Soil Moisture Effect

Poster Number 49

See more from this Division: Joint Sessions
See more from this Session: U.S. Agriculture’s Role in Soil Carbon Sequestration and Greenhouse Gas Mitigation (GRACEnet) (Posters)

Tuesday, 7 October 2008
George R. Brown Convention Center, Exhibit Hall E

Marina Molodovskaya1, Olga Singurindy1, Brian Richards1, Jon Warland2 and Tammo Steenhuis1, (1)Biological and Environmental Engineering, Cornell University, Ithaca, NY
(2)Department of Land Resource Science, University of Guelph, Guelph
Abstract:
Agricultural soils are the most significant terrestrial source of nitrous oxide (N2O), one of the three major biogenic gases contributing to greenhouse effect. Emissions can increase after manure fertilization, which is commonly applied in the Northeastern US, where dairy farms are ubiquitous.

Measurements of N2O emission were conducted on manure-amended alfalfa in 2006 and corn in 2007 fields in central New York State. Fluxes were measured with the micrometeorological eddy covariance technique using tunable diode laser absorption spectroscopy (EC-TDLAS), which allowed high-frequency (10Hz), high-resolution, continuous monitoring of N2O flux from soils. The experimental setup also included simultaneous measurements of meteorological and soil parameters, such as air and soil temperature, soil moisture, precipitation, humidity, water vapor and CO2 flux, and net radiation. The results were averaged over 30 min periods and daily values were calculated.

The preliminary analysis of data obtained during two years of observations showed emission increases after manure application, as well as the high variability and strong instantaneous ‘spike-like' nature of N2O flux. The background level of emissions stayed below 0.05ug N2O-N m-2 s-1, whereas under favorable conditions the peaks could reach up to 0.7ug N2O-N m-2 s-1 within a short time. The main variables effecting N2O production were the soil moisture and temperature. However, most of the time soil moisture variations were not substantial enough (<2%) to cause immediate flux response. The explicit N2O increase due to moisture changes only occurred during/after strong rainfall or freezing/thawing events. When soil moisture was not a limiting factor (WFPS 50-70%), soil temperature and its rapid fluctuations had more direct and immediate impact on flux formation. The N2O ‘spikes' mostly followed sharp temperature drop/rise cycles (>10oC). The highest observed N2O peaks were generated as a result of combination of recent manure application, significant soil moisture increases and strong temperature drop/rise events.

See more from this Division: Joint Sessions
See more from this Session: U.S. Agriculture’s Role in Soil Carbon Sequestration and Greenhouse Gas Mitigation (GRACEnet) (Posters)