The Effect of Soil Temperature and Water Content On Soil Respiration Under Different Land Use in Central Ohio, USA.

Since large uncertainties remain in our ability to assess terrestrial carbon-cycle, monitoring and precise modeling of soil respiration are required for different soil types, land use, geological regions and climatic zones. We conducted the measurement of soil respiration rate, surface soil temperature and volumetric soil water content from different land use in Central Ohio, including two cropland sites with conventional tillage and no-till management, one secondary forest site and two grassland sites under pasture and turf grass management. Soil respiration rate was correlated either with soil temperature or water content and tested to determine the best linear regression model to explain the variation of soil respiration rate. Comparing Akaike's Information Criteria (AIC) of the equations, we concluded that the soil respiration in those sites was controlled by soil temperature. Though the mean annual soil temperature in the pasture site was lower than in the cropland site under conventional tillage, annual soil respiration in the former site was higher than the latter. The higher temperature dependence on soil respiration in the former site would be due to the higher density of root biomass and the amount of easily decomposable organic materials released by root after grazing, mowing and clipping of the aboveground biomass.