Greenhouse gases fluxes and soil thermal properties in a pasture in central Missouri

Fluctuations of greenhouse gases emissions and soil properties occur at short spatial and temporal scales, however, results are often reported for larger scales studies. We monitored CO2, CH4, and N2O fluxes and soil temperature (T), thermal conductivity (K), resistivity (R) and thermal di usivity (D) from 2004 to 2006 in a pasture. Soil air samples for determination of CO2, CH4 and N2O concentrations were collected from static and vented chambers and analyzed within two hours of collection with a gas chromatograph. T, K, R and D were measured in-situ using a KD2 probe. Soil samples were also taken for measurements of soil chemical and physical properties. The pasture acted as a sink in 2004, a source in 2005 and again a sink of CH4 in 2006. CO2 and CH4 were highest, but N2O as well as T, K and D were lowest in 2004. Only K was correlated with CO2 in 2004 while T correlated with both N2O (r = 0.76, p = 0.0001) and CO2 (r = 0.88, p = 0.0001) in 2005. In 2006, all gases fluxes were significantly correlated with T, K and R when the data for the entire year were considered. However, an in-depth examination of the data revealed the existence of month-to-month shifts, lack of correlation and di ering spatial structures. These results stress the need for further studies on the relationship between soil properties and gases fluxes. K and R o er a promise as potential controlling factors for greenhouse gases fluxes in this pasture.