Dissolved organic carbon in old field soils : total amounts as a measure of available resources for soil mineralization

摘要: Dissolved organic carbon (DOC) and C N mineralization were measured during a 210 day regulated in vitro incubation of soils from an old field successional sequence at Cedar Creek Natural History Area. The objective the study was to evaluate hypothesis that soil DOC constitutes readily-available microbial resource, concentrations are related rates biological decomposition associated nutrient release matter. Soils five previously cultivated fields undergoing secondary succession oak savanna selected because they had demonstrated different patterns cycling. Although amounts total differed dramatically (496–1371 μmol g−1), all time collection between 0.70 1.30 g−1. During incubation, relative generally remained constant or increased while decreased. When intervals considered, there no obvious relationship instantaneous mineralization. Asymptotic exponential response curves did describe positive associations CO2-C early times (R2 = 0.98 for 14 35 days), but not later. Similar models show strong net-N rates. By end pool could potentially supply 1.5–3.4 days mineralization, rate any given concentration 3–10 lower than days. These results reflect decreased utilization supply, be caused by accumulation recalcitrant DOC.