Filter, inoculum and time effects on measurements of biodegradable water soluble organic carbon in soil

The biodegradation of organic carbon drives biogeochemical cycles. Incubations of water soluble organic carbon (WSOC) are popular tests for determining the amount of readily biodegradable organic carbon. However, tests differ in length of incubation, filtration prior to incubation, and method of incubation. We compared the fraction of biodegradable water soluble organic carbon (BWSOC) in soil by varying these factors. With all combinations, WSOC decreased to a minimum during the first 6 days then consistently increased at the later stages of the incubation. The mean BWSOC content of the soils ranged from 0.13 to 3.54, and depended on the length of the incubation and the combination of filters used before and after incubation. Similar amounts of BWSOC were measured during aerobic and anaerobic incubations.