Bohm, Sven (Michigan State University, 3700 Gull Lake Dr, Hickory Corners, MI, 49060; Phone: 51-3550223; Email: s@rootimage.msu.edu)

Near-Continuous Sampling of Soil N₂O Emissions

S. Bohm*, G.P. Robertson

We are using automated static chambers for frequent measurements of N₂O emissions from soils under four different agricultural management systems (conventional, no-till, and organic soybean-wheat-corn rotations and continuous alfalfa). N₂O emissions are sampled four times per day, and simultaneous measurements of soil moisture and temperature provide ancillary emission data, as do periodic soil nitrate measurements. Fluxes vary smoothly over the time period thus far measured, suggesting that we are capturing most of the temporal variability present in the systems. N₂O emissions often vary more than three-fold over a single day. Longer term trends appear related to soil moisture, temperature, and nitrogen availability. Maximum fluxes were nearly ten times higher in the conventional treatment than in the other treatments. Data will be used to test current models of N₂O emission, including DAYCENT.