Decomposition of added and native organic carbon from physically separated fractions of diverse soils

• Published in: Biology and fertility of soils Vol. 50; no. 4; pp. 613 - 621
• Main Authors: Jagadamma, Sindhu, Steinweg, J. Megan, Mayes, Melanie A., Wang, Gangsheng, Post, Wilfred M.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.05.2014; Springer; Springer Nature B.V
• Subjects: Agriculture; Agronomy. Soil science and plant productions; Biogeochemistry; Biological and medical sciences; Biomedical and Life Sciences; Carbon; Chemical, physicochemical, biochemical and biological properties; Decomposition; Fundamental and applied biological sciences. Psychology; Life Sciences; Organic matter; Original Paper; Physics, chemistry, biochemistry and biology of agricultural and forest soils; Soil science; Soil Science & Conservation; Soil sciences; Mineral-associated organic carbon; Native organic carbon; Glucose; Particulate organic carbon; Respiration; Organic carbon; Soils; Decomposition; Soil science; Particulate carbon
• ISSN: 0178-2762; 1432-0789
• DOI: 10.1007/s00374-013-0879-2

There have been increasing efforts to understand the dynamics of organic carbon (OC) associated with measurable fractions of bulk soil. We compared the decomposition of native OC (native C) with that of an added substrate (glucose) on physically separated fractions of a diverse suite of soils. Five soil orders were selected from four contrasting climate zones (Mollisol from temperate, Ultisol and Oxisol from tropics, Andisol from sub-arctic, and Gelisol from arctic region). Soils from the A horizon were fractionated into particulate OC (POC) and mineral-associated OC (MOC) by a size-based method. Fractions were incubated at 20 °C and 50 % water-holding capacity in the dark after the addition of unlabeled d -glucose (0.4 mg C g −1 fraction) and U– 14 C glucose (296 Bq g −1 fraction). Respiration of glucose 14 C indicated 64 to 84 % of added glucose 14 C which was respired from POC and 62 to 70 % from MOC within 150 days of incubation, with more than half of the cumulative respiration occurring within 4 days. Native C respiration varied widely across fractions: 12 to 46 % of native C was respired from POC and 3 to 10 % was respired from MOC fractions. This suggested that native C was more stabilized on the MOC than on the POC, but respiration from the added glucose was generally similar for MOC and POC fractions. Our study suggests a fundamental difference between the behavior of freshly added C and native C from MOC and POC fractions of soils.