Chemical and mineral control of soil carbon turnover in abandoned tropical pastures
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Geoderma. 143: 49-62.
We investigated changes in soil carbon (C) cycling with reforestation across a long-term, replicated chronosequence of tropical secondary forests regrowing on abandoned pastures. We applied CP MAS 13C NMR spectroscopy and radiocarbon modeling to soil density fractions from the top 10 cm to track changes in C chemistry and turnover during secondary forest establishment on former pastures. Our results showed that interaggregate, unattached, particulate organic C (free light fraction) and particulate C located inside soil aggregates (occluded light fraction) represent distinct soil C pools with different chemical composition and turnover rates. The signal intensity of the O-alkyl region, primarily representing carbohydrates, decreased, and alkyl C, attributed to recalcitrant waxy compounds and microbially resynthesized lipids, increased from plant litter to soil organic matter and with incorporation into soil aggregates.
Keywordssoil organic matter, density fractionation, radiocarbon, CP MAS 13C NMR spectroscopy, reforestation, land-use change
Marin-Spiotta, Erika; Swanston, Christopher W.; Torn, Margaret S.; Silver, Whendee L.; Burton, Sarah D. 2008. Chemical and mineral control of soil carbon turnover in abandoned tropical pastures. Geoderma. 143: 49-62.