Measuring Carbon and Energy Exchange Over a No till Agriculture Using the Eddy Covariance Technique.
Maheteme Gebremedhin1, Teferi Tsegaye2, Mezemir Wagaw1, Maifan Silitonga3, Odemari Mbuya4, and Alton Johnson5. (1) Department of Plant and Soil Science, Alabama A&M University, P.O. Box 1208, Normal, AL 35762, (2) Alabama A&M University, P.O. Box 1208, Department of Plant & Soil Science, Normal, AL 35762, (3) Alcorn State University, 1000 ASU Drive #750, Alcorn State, MS 39096, (4) Florida A&M University, 119 Perry Paige Building, Tallahassee, FL 32307, (5) Alcorn State Univesity, 1000 ASU Drive #750, Alcorn State, MS 39096
Types of land use and farming practices are key components of the agro-ecosystem that can greatly control the cycling of carbon dioxide and energy in the biosphere-atmosphere domain. Eddy covariance (EC) is a micrometeorological technique that measures the total exchange of CO2 and H2O between the biosphere and atmosphere. The turbulent motion of the upward and downward moving eddies are responsible for the net mass exchanges across the canopy-atmosphere interface Measured over a long period of time, the EC can provide estimates of net ecosystem exchange (NEE), a measure of productivity. Typically, the technique provides quantitative evidence whether a particular ecosystem is source or sink for carbon scalar of interest. This long term study is undergoing at Alabama A&M University (AAMU), Winfred Thomas Agricultural Research Station (WTARS) in Hazel Green Alabama. Preliminary results show that distinct seasonal trends in sensible (H), latent (LE) and net radiation (Rn) were observed. Following the pattern of the diurnal cycle of temperature, net radiation oscillates between a minimum (negative values) beginning sunrise and maximum (300 to 550 W/m2) in the afternoon hours. Substantial differences between latent and sensible heat is observed after rain events and latent heat flux exceeds sensible heat by a factor of 2. Net ecosystem level carbon assimilation was observed to be 0.4mg/m2/s in October. This finding suggested that C assimilation was driven by high incoming net radiation and high vapor pressure deficit in the atmosphere.