PARENT SESSION
Oral Session #98: Carbon and Nitrogen Cycling: N-addition, N-flux.
Presiding: C. Hoover
Friday, August 9. 9:00 AM to 12:00 PM. Greenlee Meeting Room, TCC.
The effect of compost application on the level of soil CO2 concentration and growth of Cinnamomum camphora seedlings.
Flores, Clariza*,1, Yahata, Hisashi2, 1 Graduate Student, Kyushu University, Fukuoka, Japan2 Institute of Tropical Agriculture, Kyushu University, Fukuoka, Japan
ABSTRACT- The CO2 concentration was evaluated in weathered soil from granite (Masado) mixed with compost material (processed organic wastes) over a 2-year period under field condition. Disposable tubes (Kitagawa gas precision detector) were used to measure the level of CO2 at different soil layers. Temporal and spatial variations of the CO2 concentrations were attributed mainly to biotic (root respiration and microbial activity) and abiotic (soil temperature and soil moisture content) factors. Observed CO2 concentrations vary through time, depth and amount of compost applied. Highest concentration was observed in September 1999 under RC 7.5% (5.30%) at 60 cm and lowest during winter (January 1999) of 0.13% at 8 cm soil depth in a Control treatment. Soil CO2 concentration was found to have strong positive correlation with temperature (r = 0.95) at 100 cm and significantly correlated with moisture content (r=0.63) at 100 cm soil depth. The effect of rainfall has not shown any significant effect on the level of CO2 concentration at different soil layers. Strong correlations of temperature at any given depth indicated temperature's significant role in determining level of CO2 concentration. Moreover, the effect of compost applied specifically at deeper soil layer at lower concentration (7.5%) greatly affected respiration rates favoring higher CO2 concentration at deeper soil layers (40 ~100cm). It was found that the observed higher CO2 concentration had no detrimental effect on the growth of plants studied.
KEY WORDS: soil CO2 concentration, compost material, soil temperature and soil moisture, Kitagawa gas precision detector