Functional dependencies of soil CO2 emissions on soil biological properties in northern German agricultural soils derived from a glacial till

Agricultural soil CO2 emissions and their controlling factors have recently received increased attention because of the high potential of carbon sequestration and their importance in soil fertility. Several parameters of soil structure, chemistry, and microbiology were monitored along with soil CO2 emissions in research conducted in soils derived from a glacial till. The investigation was carried out during the 2012 growing season in Northern Germany. Higher potentials of soil CO2 emissions were found in grassland (20.40 mu g g(-1) dry weight h(-1)) compared to arable land (5.59 mu g g(-1) dry weight h(-1)) within the incubating temperature from 5 degrees C to 40 degrees C and incubating moisture from 30% to 70% water holding capacity (WHC) of soils taken during the growing season. For agricultural soils regardless of pasture and arable management, we suggested nine key factors that influence changes in soil CO2 emissions including soil temperature, metabolic quotient, bulk density, WHC, percentage of silt, bacterial biomass, pH, soil organic carbon, and hot water soluble carbon (glucose equivalent) based on principal component analysis and hierarchical cluster analysis. Slightly different key factors were proposed concerning individual land use types, however, the most important factors for soil CO2 emissions of agricultural soils in Northern Germany were proved to be metabolic quotient and soil temperature. Our results are valuable in providing key influencing factors for soil CO2 emission changes in grassland and arable land with respect to soil respiration, physical status, nutrition supply, and microbe-related parameters.