Distinguishing Black Carbon from Biogenic Humic Substances in Soil Clay Fractions
Laird, David, Chappell, Mark, Martens, Dean, Wershaw, Robert, Thompson, Michael
Geoderma, October 3, 2007
Interpretive Summary:
Soil organic matter, often called humus, contributes substantially to the quality of soils by stabilizing soil structure and both retaining and helping to cycle plant nutrients. The chemical structure of soil humus is very complex, but has been thought in the past to be a complex polymer with a backbone of aromatic carbon. We developed a method to physically separate aged charcoal from soil organic matter. The charcoal contributed about 8% of the carbon in the three soils we studied. The charcoal was old and was not very available to soil microorganisms. The true humus was the fraction of the soil organic matter left after the charcoal had been extracted. The true humus was young and readily available to soil microorganisms. The true humus had very little aromatic carbon; rather it was a mixture of fatty acids and sugar-like structures. This discovery means that many of the previously proposed models for the structure of soil humus are wrong, because most of the aromatic carbon is in the charcoal not in the true humus. This study will help scientists to understand how soil organic matter is formed and stabilized in soils. Such information is needed to design agricultural management systems that build soil organic matter. Policy makers need to understand that charcoal is a natural component of soils and that adding charcoal to soils will help build soil quality because in the future conservation practices may include adding charcoal to soils.
Technical Abstract:
Most models of soil humic substances include a substantial component of aromatic carbon (C) either as the backbone of humic heteropolymers or as a significant component of supramolecular aggregates of degraded biopolymers. Here we report that most of the aromatic C in the clay fraction of three studied soils was associated with discrete particles (0.2-2 um) of pyrogenic black carbon (BC), which were physically separated with the coarse clay subfraction. The physically separated BC particles contained approximately 60% aromatic C, with the remainder being a mixture of aliphatic, anomeric and carboxylic C. We hypothesize that as BC particles aged in soils their surfaces were oxidized to form carboxylic groups. Further, we suggest that anomeric and aliphatic C accumulated in BC particles either by adsorption of dissolved biogenic compounds from the soil solution or by direct deposition of biogenic materials from microbes living within the BC particles. The biogenic soil organic matter that was physically separated with the medium and fine clay subfractions was dominated by aliphatic, anomeric, and carboxylic groups with little aromatic C and existed as diffuse filamentous clumps and films binding clay particles together. The lack of aromatic C in the biogenic soil organic matter is inconsistent with the heteropolymer model for the formation of humic substances.
Black carbon
Distinguishing Black Carbon from Biogenic Humic Substances in Soil Clay Fractions
Submitted by Tom Miles on Sun, 2007-12-02 18:06.Long-Term Black Carbon (Bio-Char) Dynamics in Cultivated Soil
Submitted by Tom Miles on Mon, 2007-03-05 03:29.Long-Term Black Carbon (Bio-Char) Dynamics in Cultivated Soil
Binh Thanh Nguyen, Johannes Lehmann, and James Kinyangi. Cornell Univ, 1022 Bradfield Hall, Ithaca, NY 14853
18th World Congress of Soil Science (WCSS) July 9-15, 2006 - Philadelphia, Pennsylvania, USA
Bio-char Black Carbon) Stability and Stabilization in Soil
Submitted by Tom Miles on Mon, 2007-03-05 03:24.Bio-char (Black Carbon) Stability and Stabilization in Soil
Johannes Lehmann, Cornell Univ, Ithaca, NY 14850 and Saran Sohi, Rothamsted Researchi, Harpenden, AL5 2JQ, United Kingdom
18th World Congress of Soil Science, July 9-15, 2006 - Philadelphia, Pennsylvania, USA
Black C Effects on the Biogeochemical Cycling of Soil Nutrients and Organic C in Amazonian Dark Earths (Terra Preta De Indo)
Submitted by Tom Miles on Mon, 2007-03-05 02:54.Black C Effects on the Biogeochemical Cycling of Soil Nutrients and Organic C in Amazonian Dark Earths (Terra Preta De Indo)
Biqing Liang, Graduate Student, Department of Crop and Soil Sciences, Cornell University, 9/21/2006,Crop and Soil Sciences Seminar Series, Cornell University. College of Agriculture and Life Sciences.
Abstract:
Black carbon in a temperate mixed-grass savanna
Submitted by Tom Miles on Mon, 2007-01-22 05:28.Black carbon in a temperate mixed-grass savanna
X. Daia, T.W. Boutton a,*, B. Glaser b, R.J. Ansley c, W. Zech b
Soil Biology & Biochemistry 37 (2005) 1879–1881
Abstract
Black carbon (BC) or charcoal is thought to represent an important component of the carbon cycle, but has seldom been quantified in soils. We quantified soil BC in a temperate mixed-grass savanna in the southern Great Plains using benzenecarboxylic acids as molecular markers for BC. Soils were collected from four fire treatments (repeated summer fires in 1992 and 1994; repeated winter fires in 1991, 1993 and 1995;
An Investigation of Black Carbon Degradation Potential in a Forest Soil Environment
Submitted by Tom Miles on Mon, 2007-01-22 05:11.An Investigation of Black Carbon Degradation Potential in a Forest Soil Environment
William, H. C.; Lee, E.; Grannas, A.; Hatcher, P. G.
American Geophysical Union, Fall Meeting 2003, abstract #B21B-0711, 12/2003
Abstract
Except for emission processes, there is currently little understanding of the mechanisms driving the degradation and biogeochemical cycling of black carbon (BC). Considering current estimates of the global BC pool (>2,500x1015gC), and its annual emission rates (55-205x1012 gC/year), BC represents roughly 16% of Earth's actively cycling organic carbon. Without significant chemical and biological degradation pathways, all of the actively cycling carbon on earth would have accumulated as charcoal in <100,000 years. This investigation show that charcoals recovered from experimental forest fires are altered significantly by microbial colonization, and mineral complexation during exposure to soil processes. Charcoal surface morphology and elemental composition were characterized by scanning electron microscopy, energy dispersive X-ray spectroscopy, and BET surface area measurements. The influence of 90 years aging upon carbon functionality was probed by solid-state 13C NMR spectroscopy. The prevalence of fungal mycorhizae in these forest soil charcoals also motivated an investigation of black carbon degradation via extracellular enzymes and acids known be exuded by mycelia. Degradation is quantified by carbon loss, and soluble products are examined by mass spectrometry.
Black Carbon from Rice Residues as Soil Amendment and for Carbon Sequestration
Submitted by Tom Miles on Mon, 2007-01-22 04:58.Black Carbon from Rice Residues as Soil Amendment and for Carbon Sequestration
Stephan M. Haefele 1, J.K. Ladha 1, and Yothin Konboon 2.
(1) International Rice Research Institute, Los Banos, 4031 Laguna, Philippines, (2) Ubon Rice Research Centeri, Ubon Ratchathani, Thailand
18th World Congress of Soil Science, July 9-15, 2006 - Philadelphia, Pennsylvania, USA
On highly weathered soils in tropical and subtropical climates, maintenance of soil organic matter is essential to sustain system productivity and avoid rapid soil degradation. But climatic conditions as well as soil characteristics favor the rapid decomposition of organic matter. However, several recent studies indicated that black carbon, the product of incomplete combustion of organic material, could combine characteristics highly beneficial for soil nutrient dynamics with high stability against chemical and microbial breakdown. Lasting soil amelioration by incorporation of black carbon from wooden plants was proposed based on the beneficial evidence from “Terra Preta” soils in Western Amazonia. Theoretically, charred crop residues in rice-based systems could serve the same purpose but this hypothesis has never been tested. Within this context, our objectives were to 1) assess possible options for the use of charred rice residues, to 2) test the effect of charred rice residues on important soil fertility parameters and rice growth, and 3) to evaluate the effect and stability of charred rice residues in a variety of rice growing environments.
Exploring Atypical Stabilization Pathways Using Pool-Based Modeling
Submitted by Tom Miles on Mon, 2007-01-22 04:37.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.
Isolating Unique Bacteria from Terra Preta Systems: Culturing and Molecular Tools for Characterizing Microbial Life
Submitted by Tom Miles on Mon, 2007-01-22 03:48.Isolating Unique Bacteria from Terra Preta Systems: Using Culturing and Molecular Tools for Characterizing Microbial Life in Terra Preta
O'Neill, Brendan Grossman, Julie Tsai, S.M. Gomes, Jose Elias Garcia, Carlos Eduardo Solomon, Dawit Liang, Biqing Lehmann, Johannes Thies, Janice
Poster presentation from the 2006 World Congress of Soil Science in Philadelphia, PA
16-Aug-2006
The greater fertility of Terra Preta (TP) soils is thought to be due to their high black carbon (BC) content, which contributes to increased nutrient and moisture retention, and increased pH.
Black Carbon from Rice Residues as Soil Amendment and for Carbon Sequestration
Submitted by Tom Miles on Mon, 2007-01-22 03:32.Black Carbon from Rice Residues as Soil Amendment and for Carbon Sequestration
Haefele, SM, Konboon, Y, Knoblauch, C, Koyama, S, Gummert, M, Ladha, JK
Cornell University Poster Presented to International Rice Research Institute, September 14 2006
On highly weathered soils in tropical and subtropical climates, maintenance of soil organic matter is essential to sustain system productivity and avoid rapid soil degradation. But climatic conditions as well as soil characteristics favor the rapid decomposition of organic matter. However, several recent studies indicated that black carbon, the product of incomplete combustion of organic material, could combine characteristics highly beneficial for soil nutrient dynamics with high stability against chemical and microbial breakdown.
