Land Use Effects and Spatial Variation of Greenhouse Gas Emissions From Missouri Floodplain Soils.

Agriculture is estimated to contribute 10-14% of global greenhouse gas (GHG) emissions largely through the efflux pathways of three gases: carbon dioxide, methane, and nitrous oxide.  These statistics of GHG emissions are based on limited data and lack specificity to regions such as the Missouri River Floodplain.  This floodplain was once heavily covered with bottomland forest, but is now predominately cleared and managed for agricultural production.  The objectives of this study are to evaluate soil greenhouse gas emissions responses to differences in soil moisture, temperature, land use, and nitrogen inputs as well as to characterize the spatial patterns of GHG emissions within the land uses of agroforestry, row-crop agriculture, and natural systems within the floodplain soils adjacent to the Missouri River.  A preliminary laboratory study was conducted using8 cm diameter surface soil cores to test for influences of management and soil water content on GHG emissions.  Water treatment was found to be significant in both methane and carbon dioxide emissions.  An interaction of water treatment and land use was found to be significant in nitrous oxide emissions.  Intensive in situ sampling is planned for the 2011 growing season using static closed chamber methods to evaluate the spatial variation of GHG emissions.  The data from this study will be used in establishing a statistically sound method for measuring cumulative soil GHG emissions.