CARBON MINERALIZATION IN PRISTINE AND PHOSPHORUS-ENRICHED PEAT SOILS OF THE FLORIDA EVERGLADES

Differences in microbial mineralization of added organic carbon were assessed in pristine (0.231 g total P (TP) kg(-1)) and P-polluted (1.473 g total P kg(-1)) neutral peat soils from Everglades National Park, Florida. Kinetic parameters associated with CO2 and CH4 evolution from glucose added to the two soils were significantly different, and the extent of evolution of both gases was greater in the high TP soil over a range of 1 to 5 mol added glucose C kg(-1) soil. Carbon mineralization, measured as the sum of CO2 and CH4 evolved from added acetate, glucose, cellulose, or sawgrass, was significantly more extensive in the high TP soil. The lag time before the onset of CH4 evolution was shorter and the fraction of gases evolved composed of CH4 higher in the high TP soil for all substrates tested. Addition of PO4 stimulated C mineralization in low TP soil amended with acetate, glucose, or sawgrass, but either had no effect or depressed mineralization of these substrates in the high TP soil. No significant differences in rates of CH4 oxidation were observed between the two soils. Our results indicate that soil P levels may play a significant role in determining the relative importance of aerobic and anaerobic microbial metabolism in these soils.