In bulk soil, the decomposition of organic matter such as leaf litter accounts for the majority of volatile organic compounds present in the substrate. These compounds have various fates including release to the atmosphere and consumption by soil microbial communities. Although the volatile organic compound profile released from litter varies with plant species, methanol and acetone are common to many litters, with methanol comprising approximately 90% of volatile organic compounds released from some litters. In this study, we aimed to determine what effect methanol and acetone had on the carbon dynamics in soil using a microcosm incubation approach. We added methanol or acetone weekly and measured respiration throughout the duration of the experiment. At the end of the experiment, we measured carbon mineralization, microbial activity, microbial biomass, and carbon fractions in the soil and microbial biomass.
Results/Conclusions
Both treatments had significantly higher respiration rates than the control and there were significant pulses in respiration corresponding with the addition of methanol or acetone. Carbon mineralization rates were also higher than the control in both treatments. However, there were no significant differences in microbial activity, microbial biomass or any of the carbon pools. This leads us to propose that as volatile organic compounds enter the soil substrate then cause short-term increases in microbial activity. This is possibly due to starved microorganisms consuming volatile compounds that are able to reach them in nutrient poor locations of the soil. Furthermore, total soil nitrogen and inorganic nitrogen pools varied significantly between the treatments and the control. These changes in carbon and nitrogen cycling lead us to believe that couple Carbon and Nitrogen dynamics are modulated by volatile organic compound consumption.