Availability of organic carbon in soluble and particle-size fractions from a soil profile

Nelson, P.N., Dictor, M-C., and Soulas, G. (1994) Availability of organic carbon in soluble and particle-size fractions from a soil profile. Soil Biology and Biochemistry, 26 (11). pp. 1549-1555.

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Abstract

an agricultural soil profile, the availability of soil organic C for microbial activity decreased from 0 to 100 cm depth in winter, spring and summer. Availability was defined as the ratio of respiration rate to total organic C, or the ratio of microbial biomass C to total organic C. The amount and availability of organic C in various soil fractions was measured. Fractions consisted of aqueous extracts from throughout the profile, and particle-size and density fractions from the O-20 and SO-100 cm layers. The fractions were incubated with soil inoculum for 24 or 28 days. Availability of organic C in soluble fractions was measured by the decrease in dissolved organic C. Availability of organic C in insoluble fractions was measured by the increase in inorganic C. Availability of organic C in all fractions was similar at each depth, except for the weakly-adsorbed and clay fractions, in which organic C was less available at depth. Availability was least in the silt fractions. Approximately half of the organic C mineralized during incubations originated from the clay fraction in both the &lo and SO- 100 cm layers. Of the remainder, at the surface a higher proportion was in the silt and light (> 50 um, d< 2 g cm- 3, fractions, due to a larger proportion of total organic C in those fractions. At depth, a higher proportion was in the extracted fractions. The decrease in the availability of total organic C with depth appeared mainly to be due to a decrease in the accessibility of organic C to microorganisms, and a decrease in the availability of clay fraction organic C.

Item ID: 11719
Item Type: Article (Refereed Research - C1)
ISSN: 1879-3428
Date Deposited: 26 Aug 2010 06:16
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050303 Soil Biology @ 50%
05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences > 050304 Soil Chemistry (excl Carbon Sequestration Science) @ 50%
SEO Codes: 96 ENVIRONMENT > 9614 Soils > 961402 Farmland, Arable Cropland and Permanent Cropland Soils @ 100%
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