Carbon monoxide, hydrogen, and methane uptake by soils in a temperate arable field and a forest

CO, H-2 and CH4 uptake by the soil of an arable field and a forest soil (36 0 m apart) was measured by a closed-chamber method in temperate Japan for a bout 1 year. CO production observed was exponentially dependent on top soil temperature. CO production was greater in the forest soil than in the soil of the arable field at the same soil temperature. 2 (Gross) CO, H-2 and CH 4 deposition velocities ranged from 0 to 7X 10(-2), from 0 to 9X 10(-2) and from 0.05 to 0.1X 10(-2) cm s(-1) in the arable field and from 1.5 to 4.5X 10(-2), 5 to 8X 10(-2) and from 0.3 to 0.6X 10(-2) cm s(-1) in the forest, respectively. Variations in the deposition velocities were smaller in the forest than in the arable field and corresponded to variations in soil mois ture in the top soil. Seasonal trends caused by the variation in temperatur e were observed only for CH4 deposition, reflecting the clear dependence on soil temperature. Application of dead plant material to the arable field l ed to acceleration of CO and H-2 deposition onto the soil, The deposition v elocities of CO and H-2 were positively correlated (n=36, R-2* = 0.881, p<0 .0001; R-2* is the coefficient of determination adjusted by, degrees of fre edom) in the arable field and (n=37, R-2* = 0.308, p<0.0001) in the forest, suggesting diffusion control on their deposition velocities.