Comparison of Eddy Covariance and Chamber-Based Methods for Measuring Gaseous Emissions From Moderately Dry Soils.

There are many uncertainties when determining absolute values of soil component fluxes. Although widely used, chamber techniques include some weaknesses such as pressure effects and spatial and temporal variability in gas fluxes. The eddy covariance technique is used for measuring energy, water, carbon dioxide (CO₂), ammonia (NH₃), and pesticide fluxes to facilitate on site monitoring and simulation of gas fluxes. For this technique, the required primary data are profiles of gas concentration on the downwind boundaries as well as the wind speed profile, the wind direction and the upwind background gas concentration. This combination of measurements provides a powerful new tool for measuring gas emissions from treated areas and intensive animal feeding operations (AFOs). Two methods, eddy covariance and chamber-based measurements, will be employed to measure gaseous emissions of fumigant pesticides from moderately dry soils under field conditions. A comparison of the two methods will be presented.