Monday, 7 November 2005
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Soil Properties and CO2, CH4, and N2O Emissions from a Pasture in Missouri.

Nsalambi Nkongolo and Kent Schmidt. Lincoln University, Center of Excellence GIS Laboratory, 820 Chestnut Street, 307 Founders Hall, Jefferson City, MO 65102-0029

We assessed the relationship between CO2, CH4 and N2O fluxes and soil thermal conductivity (K), resistivity (R) and diffusivity (D). The study was conducted in 2004 and 2005 in a permanent pasture at Lincoln University's Washington Carver Farm. Sixteen static and vented chambers were installed permanently in a 400 by 400 m plot at 100 m spacing since 2003. Soil samples collection for analysis of chemical and physical properties and direct measurement of soil thermal properties were conducted yearly from June to December. A KD2 probe was used to measure thermal properties at 0.06 m depth inside and near each chamber. Soil air samples for determinations of CO2, CH4 and N2O were also collected when measuring soil thermal properties. Analysis of CO2, CH4 and N2O from air samples was done within two hours of sampling at Dickinson Research Center with a Shimadzu Greenhouse Gas GC-14. Integrated fluxes for 2004 and 2005 showed that CO2 ranged from 17.25 to 336.67 mg CO2-C m-2 h-1, CH4 uptake from 59.26 to 107.20 ug CH4–C m-2 h-1 and N2O from –14.58 to 96.04 ug N2O-N m-2 h-1. Except for N2O which only correlated with K and D, CO2 and N2O fluxes were either linearly, exponentially or quadratically correlated with K, R, D and soil temperature with coefficient of correlation (r) ranging from 0.35 to 0.80. In addition, CO2, N2O and CH4 also correlated among themselves with (r) ranging from 0.40 to 0.90. These results suggest that soil thermal properties may be important factors in controlling greenhouse gas fluxes from soils to the atmosphere.

Handout (.pdf format, 175.0 kb)

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