초록 close

From October 2009 to June 2010, major greenhouse gases (GHG: N2O, CH4, CO2) soil emission were measured from upland cabbage field at Kunsan (35􀆆56′23′′N, 126 43′14′′E), Korea by using closed static chamber method. The measurements were conducted mostly from 10:00 to 18:00LST during field experiment days (total 28 days). After analyzing GHG concentrations inside of flux chamber by using a GC equipped with a methanizer (Varian CP3800), the GHG fluxes were calculated from a linear regression of the changes in the concentrations with time. Soil parameters (e.g. soil moisture, temperature, pH, organic C, soil N) were also measured at the sampling site. The average soil pH and soil moisture were ~pH 5.42±0.03 and 70.0±1.8 %WFPS (water filled pore space), respectively. The ranges of GHG flux during the experimental period were 0.08~8.40 mg/m2∙hr for N2O, -92.96~139.38 mg/m2∙hr for CO2, and -0.09~0.05 mg/m2∙hr for CH4, respectively. It revealed that monthly means of CO2 and CH4 flux during October (fall) were positive and significantly higher than those (negative value) during January (winter) when subsoil have low temperature and relatively high moisture due to snow during the winter measurement period. Soil mean temperature and moisture during these months were 17.5±1.2℃, 45.7±8.2%WFPS for October; and 1.4±1.3􀆆C, 89.9±8.8 %WFPS for January. It may indicate that soil temperature and moisture have significant role in determining whether the CO2 and CH4 emission or uptake take place. Low temperature and high moisture above a certain optimum level during winter could weaken microbial activity and the gas diffusion in soil matrix, and then make soil GHG emission to the atmosphere decrease. Other soil parameters were also discussed with respect to GHG emissions. Both positive and negative gas fluxes in CH4 and CO2 were observed during these measurements, but not for N2O. It is likely that CH4 and CO2 gases emanated from soil surface or up taken by the soil depending on other factors such as background concentrations and physicochemical soil conditions.