Japanese Researchers Uncover Chemical Process of Leaf Litter Turning into Organic Soil Matter

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The Forestry and Forest Products Research Institute in Japan announced on September 9, 2009, that it had, for the first time, uncovered the chemical process behind leaf litter decomposing into soil organic matter. The study was conducted jointly with National Institute for Agro-Environmental Sciences, using solid-state ¹³C nuclear magnetic resonance (NMR) spectroscopy, which is a useful tool for analyzing the chemical structure of organic matter in fallen leaves and soil without any complicated pretreatment.

In the study, the ¹³C NMR method was used to identify the humification process - the transformation of organic matter into humus - of the leaf litter of two tree species: Japanese beech (Fagus crenata) and oak (Quercus crispula). Despite a difference in initial organic matter composition, the results showed a significant drop in O-alkyl carbon during the humification process in both litter species. In comparison, the content of aliphatic, aromatic, and carbonyl carbons - these organic carbons slow in decomposition rate - were found to be relatively on the rise, making the organic matter composition of both species akin to each other over a period of three years - one much closer to that of soil. Furthermore, organic carbon accumulation process on a deciduous broad-leaved forest floor was simulated using the decomposition rate of each organic carbon compound. The results showed that, over a period of ten years, forest floor including topsoil would stock as much as four tons of carbon per hectare.

The ¹³C NMR spectroscopy is an innovative method that provides uniform, non-destructive, and simultaneous measurements of organic composition, which would otherwise have to be performed separately for each target sample. It has enabled better and comprehensive understanding of the carbon input mechanism in forest soils, and is expected to contribute to global warming studies.

Japanese Researchers Warn of Global Warming Impacts on Soil Carbon Storage (Related JFS article)
http://www.japanfs.org/en/pages/028811.html
Japanese Forest Soils Consume Twice the Methane of Those in the US and Europe (Related JFS article)
http://www.japanfs.org/en/pages/027015.html
Forestry and Forest Products Research Institute official website
http://www.ffpri.affrc.go.jp/e_version/index-e.html

Posted: 2010/03/20 06:00:15 AM