Exploring Atypical Stabilization Pathways Using Pool-Based Modeling
Sohi, Saran, Yates, Helen, Lehmann, Johannes Liang, Biqing, Gaunt, John
Cornell University WCSS Poster 2006

Simulation models that explicitly account for the impact and interaction of soil and environmental variables can assist in predicting the accumulation of C and its rate of turnover. Relevant, verifiable (i.e. measurable) pools of Soil Organic Matter (SOM) provide the most robust basis for elucidating the underlying mechanisms. We have developed a model based around three measurable pools of SOM which can be measured using a density-based fractionation procedure, and verified by extensive chemical characterization. The model has been optimized against measurements of C and N and isotope-tracers in several soils amended with isotope-labeled organic matter. According to recent estimates black C is a much larger component of Soil Organic Carbon (SOC) in typical agricultural soils than previously assumed. Since black C may also be the most stable form of organic C in the soil, the amount of black C in the soil must impact both on the bulk rate of soil C mineralization (turnover) and the extent to which a particular management intervention can alter SOC. Until now our simulations have not accounted explicitly for the effect of black C on the dynamics of each pool. We are now examining how black C is characterized by physical location within the soil matrix, and in order to account for the influence of black C using this model affects C mineralization, and the distribution of charcoal between each of the measured fractions.

Terra Preta de Indio
Johannes Lehmann. Soil Biogeochemistry, Cornell University January 2007

"Terra Preta de Indio" (Amazonian Dark Earths; earlier also called "Terra Preta do Indio" or Indian Black Earth) is the local name for certain dark earths in the Brazilian Amazon region. These dark earths occur, however, in several countries in South America and probably beyond. They were most likely created by pre-Columbian Indians from 500 to 2500 years B.P. and abandoned after the invasion of Europeans (Smith, 1980; Woods et al., 2000). However, many questions are still unanswered with respect to their origin, distribution, and properties.