Greenhouse Gas Emissions in Agroecosystems

Greenhouse Gas Emissions in Agroecosystems

Greenhouse gas emissions from agricultural soils are a large part of the global production of greenhouse trace gases. Trace gases including carbon dioxide, methane and nitrous oxide are labeled as such because they make up only 0.04% of the atmospheric gas composition. Anywhere from 40 to 80 percent of global greenhouse gas emissions are considered to originate with agriculture. The flux from agricultural and natural production of greenhouse gas emissions is highly variable (Holland et al., 1999). Some of the variability seen in agricultural production of greenhouse gas emissions can be attributed to different soil types and characteristics along with production and management strategies. There is considerable interest today to understand the various factors that influence the production of these gases in the managed soils of the earth. This information can then be used to develop a global scale perspective to understand how human land use practices affect trace gas dynamics.

The gases carbon dioxide (CO2), methane (CH4), and nitrous oxide (N2O) are of primary significance when considering greenhouse gas emissions. These gases are radiatively active and persist for extended periods of time in the atmosphere. As a result, they contribute substantially to the overall radiation balance of the earth (Holland et al., 1999). Methane and nitrous oxide together account for around 20% of the total contribution of atmospheric gases to global warming (Rodhe, 1990). Methane is increasing in the atmosphere at the rate of around 1.1% per year (Cicerone and Oremland, 1988). Nitrous Oxide is increasing at the rate of approximately 0.25% per year (Prinn, 1990). Increases in the production of these gases are thought to account for the majority of the overall increases seen in atmospheric concentrations. There is also the possibility that atmospheric concentrations are affected by changes in the ways that these gases are...