The Effect of Temperature on Decomposition at Optimum and Saturated Soil Water Contents

Abstract

A laboratory study was conducted to evaluate the effect of temperature on decomposition in a silt loam soil under saturated (0.32 g/g) and optimal (0.19 g/g) soil water contents. Sewage sludge was the carbon substrate. Cumulative CO2‐C data were obtained for three temperatures (14, 22, and 30°C), and two substrate groups (rapid, intermediate) for the saturated and optimal water contents. Decomposition followed first‐order kinetics. The temperature effect for each substrate and water content was described by regressing the natural logarithm of the first‐order rate constant on the inverse of the absolute temperature. No significant differences in slopes between substrates within a water content were found for these regressions. Slopes were significantly different between water contents. The slopes were −8975 and −2660 K for the unsaturated and saturated soils, respectively. At saturation the much smaller rate of change in the rate constant, k, with temperature (slope) indicated that temperature had a much smaller influence on decomposition rate under saturated than under unsaturated conditions. Intercepts from the above regressions were significantly different between substrates and water contents. For the unsaturated soil, intercepts were 25.86 and 29.41 for the rapid and intermediate substrates, respectively. Parallel intercepts at saturation were 3.48 and 2.36, respectively. Differences in intercepts between water contents combined with slopes resulted in smaller k values for the saturated soil. These results pointed out that a single equation describing the effect of temperature on the first‐order rate constant should not be applied to the decomposition of organic matter in both unsaturated and saturated soils.

Modeling dissolved organic carbon in temperate forest soils: TRIPLEX-DOC model development and validation

“…4). These predications are consistent with results from field observations (Michalzik and Matzner, 1999;Kaiser et al, 2002) and laboratory studies (Clark and Gilmour, 1983;Christ and David, 1996;Gödde et al, 1996;Moore et al, 2008), which documented a generally increasing DOC production with increasing soil temperature and moisture. DOC concentrations are higher in the growing season than in non-growing seasons mainly because of the greater microbial activity in response to higher temperatures and moisture of the forest floor (Kalbitz et al, 2000;Yano et al, 2000;Kaiser et al, 2001).…”

Microbial decomposition of skeletal muscle tissue (Ovis aries) in a sandy loam soil at different temperatures

“…These phenomena were apparently regulated by temperature and are similar to the decomposition dynamics of other organic nutrient patches of high quality such as earthworm residues (Hodge et al, 2000), sewage sludge (Clark and Gilmour, 1983;Díaz-Burgos et al, 1993;Ajwa and Tabatabai, 1994), manure (Ajwa and Tabatabai, 1994) and plant material (Dilly and Munch, 1996). At 12 and 22 °C the rate of mass loss and CO 2 evolution slowed following the initial period of rapid decomposition.…”

Vegetation and elevation influence the timing and magnitude of soil CO<sub>2</sub> efflux in a humid, topographically complex watershed

“…Decreased moisture inputs for Stringer Creek resulted in significant responses in fluxes across landscape positions, but the riparian areas respond similarly to the entirety of the Weimer Run watershed in our study, with dry years resulting in increases in carbon fluxes. It has been shown in previous studies (Clark and Gilmour, 1985;Davidson et al, 2000;Sjogersten et al, 2006;Pacific et al, 2008) that a production optimality of surface CO 2 efflux exists in response to soil water content such that peak rates of surface CO 2 efflux coincide with medial values of soil water content, with soil water varying both temporally and spatially (with elevation). Our study adds the dimension of vegetation to this model, demonstrating that vegetation heterogeneity can have significant effects on surface CO 2 efflux within humid watersheds, particularly during periods of below-average soil water availability.…”