Charcoal Stability and Storage in Soils
|Charcoal has been found in soils and radio carbon dated to tens of thousands of years old, it does break down bio-chemically*. The rate of decomposition is based on the time, texture, depth, temperature, moisture, reactivity, and total organic carbon (Frink1999). The rate is measured in thousands of years for typical farm applications and will have a minimal impact on calculating sequestration rates. However, this work will need to be done. Here are links to various research areas.|
E N (1994) Effects of wood carbonization on soil and initial development
of seedlings in miombo woodland, Zambia. Forest Ecology & Management.
1994. 70(1/3): 353-357.
On charcoal spots - the site of charcoal production using the traditional earth kiln method - in miombo woodland in central Zambia, tree regeneration (both of indigenous species such as Brachystegia manga and Julbernardia globiflora, and exotic species such as Gmelina sp. and Eucalyptus sp.) is much slower and less successful than on areas outside the spots. An assessment was made of the effects of charcoal production on soil nutrients in the field and seedling growth (of seven indigenous woody plants) under laboratory conditions, from August 1992 to March 1993, in the Chitemalesa area. Charcoal was gathered from three kiln sites in June (at one site) and November 1992, and local people intercropped maize [Zea mays] and pumpkin [Cucurbita sp.] on all spots during the 1992-93 rainy season (December-March). Soil samples were collected (0-10 cm and 11-30 cm depths) from within and without the charcoal spots. Charcoal production increased soil pH and exchangeable P and K. Generally seed germination was better in soil with charcoal than in undisturbed soil among the seven indigenous woody plants studied (Acacia polyacantha, Bauhinia petersiana, Isoberlinia angolensis, Pterocarpus angolensis, Swartzia madagascariensis, Tamarindus indica and Ziziphus mauritiana). Seedling growth in charcoal soil was good, except for I. angolensis which had a lower growth rate than in undisturbed soil.
Up to 50% of the organic matter in most soils is unextractable by standard methods. This unextractable matter contains undecomposed plant remains, remnants of apolar aliphatic polymers, charcoal, and strongly mineral-bound matter. In the light of global carbon dynamics, the very strongly bound fraction, which is very stable over time, is extremely important. This project aims to characterize this fraction. It is isolated through various extraction procedures. Characterization is by pyrolysis-GC/MS or equivalent methods.
the Kansai Electric Group Doing (PDF)
- ... using charcoal as medium to improve the soil
and to purify water. ?? Outline of business feasibility study in Indonesia
Project name Site Contents Duration ...
Soil Carbon Sequestration by Holocene Fires Inferred from Soil Charcoal in
the Dry French Alps (pp
Christopher Carcaillet and Brigitte Talon
The current global carbon budget has a missing sink, which is believed to be in terrestrial ecosystems. At least one carbon sink, wood charcoal sequestrated in soil, remains poorly detailed. We estimate the wood charcoal-carbon content in soils located in dry valleys within the French Alps. Soils were sampled at five sites along altitudinal transects, from the conifer-dominated subalpine forests to the alpine grasslands. The five sites were distributed along a bioclimatic and biogeographic gradient from the southern Mediterranean to the northern continental Alps. The altitudinal distribution of charcoal exhibits the same pattern in the five sites, despite stand fire history, and regional bioclimatic and biogeographic differences. Charcoal concentrations are low (0.01 to 10 gchar m-2) in soils from the current treeless belt, while soils at lower elevation show high concentrations (10 to 2000 gchar m-2). The results suggest that the landscape structure determine the charcoal accumulation throughout variability of vegetation type and fire frequency. Charcoal concentrations recorded in the subalpine belt in the Alps are similar to those of Swedish boreal forests, but are 10 to 100 times lower than values from Mediterranean ecosystems. Dry to subhumid ecosystems contain subfossil carbon in the form of charcoal, which should be explicitly taken into account in the global carbon budget.
ęCopyright 1992 Eastern States Archaeological Federation
THE CHEMICAL VARIABILITY OF
CARBONIZED ORGANIC MATTER THROUGH TIME
Douglas S. Frink
Archaeology Consulting Team, Inc.
Essex Junction, Vermont.
The interdependent dynamics of climate, biota, relief, parent material and time
affect the evolution of both soils and archaeological remains within the soil. Carbon-ized
organic matter, charcoal, is one class of archaeological material subject to these
environmental factors. Although charcoal is generally presumed to be immune to
environmental influences, chemical analyses of feature soils containing charcoal from
archaeological sites throughout New England demonstrate its susceptibility to the
effects of environmental factors. Calculation of a formula of the interdependent dynamics
of these environmental factors provides some understanding of the specific
influences of each factor. This formula, when expressed in terms of the factor time,
provides an independent, inexpensive and accurate means to determine the age of
archaeological charcoal. The low cost and ease of this procedure is well-suited to environmental,
geological and archaeological disciplines. Since this is a chemical procedure,
relatively young charcoal can be dated without the problems found in radiocarbon
dating of young charcoal.
The interdependent dynamics of climate, biota, relief, parent material and time
are generally recognized as the prime causes for the development of soils (Jenny 1941).
As soil constitutes the contextual matrix of most archaeological deposits, these five
factors are likely to have an influence on certain classes of archaeological deposits. One
such class, carbonized organic matter or charcoal, is affected by these five soil formation
factors in ways that have implications for archaeological research. Organic matter,
whether used for food, clothing, structures, tools or fuel, constitutes the largest class of
cultural remains. However, this particular class of artifacts is extremely susceptible to
biochemical alterations in its form, (i.e., decay), and dispersement of its parts due to
natural recycling and leaching of elements. The net result is that little surviving evidence
of this class of cultural material is found in an archaeological context (Schiffer
One form of organic matter which does survive in archaeological context is
carbonized organic matter resulting from human activities (i.e., cooking hearths) or
natural events (e.g., environmental fires)(Schiffer 1987). Carbonized organic matter,
often referred to as charcoal, consists mainly of elemental carbon and inorganic com-pounds,
and is generally thought to be immune to biochemical decay and natural
recycling (e.g., Dowman 1970).......(click link for more)
Selected text: A portion of : The OCR Carbon Dating Procedure and Its
Application at the Rmiz Site, Czech Republic
The OCR Carbon Dating procedure measures the site-specific rate of biodegradation of organic carbon, either as soil humic material or as charcoal. SLIDE 2 (Carbon cycle) While some forms of organic carbon, such as fresh organic matter, are quickly recycled, other more resistant forms, such as humus and charcoal, are recycled at a much slower rate. This recycling follows a linear progression though time when considered within the site-specific context, and includes factors that influence biochemical degradation of organic carbon. Charcoal and soil humic material, once though to be inert, are biologically recycled at a slow, but measurable, rate (Frink 1992).
The effect of the biochemical degradation of charcoal and soil humic material is measured by a ratio of the total organic carbon to the readily oxidizable carbon in the soil sample. In general, as the total amount of organic carbon decreases though time due to recycling, the relative percentage of readily oxidizable carbon increases. This ratio is called the Oxidizable Carbon Ratio, or OCR. The rate of biochemical degradation will vary within the specific physical and environmental contexts of the sample. An age estimate of the organic carbon is determined through a systems formula that accounts for the biological influences of oxygen, moisture, temperature, carbon concentration, and the soil reactivity SLIDE 3 (OCRDATE formula). Residual influences on this system are included through a statistically derived constant (Frink 1994). (click link below to read entire artile)
A PROPOSED SOLUTION TO SOME OF THE
PROBLEMS ENCOUNTERED WITH RADIOCARBON DATA
Recent studies have demonstrated that carbonized organic matter, or charcoal,
within a soil context undergoes chemical changes over time (Frink 1992). These
changes are directly related to the age of the sample within the environmental contexts
of climate, biota, relief, and the soil chemical and textural matrix. Results from this
study determined that charcoal undergoes biochemical alterations over time which are
detectable through simple, inexpensive chemical procedures. Variability in the chemi-cal
analysis was found to be directly dependent on specific environmental factors such
as rain fall and temperature, and contextual factors such as soil texture, pH, and the
depth of the sample below the surface.
The two chemical analyses used in this procedure determine the total percent-age
of carbon and the percentage of readily oxidizable carbon in the sample. The
results are converted to a ratio of total carbon to the readily oxidizable carbon in each
sample, the Oxidizable Carbon Ratio ("OCR"). The OCR value is then factored into
an environmentally based contextual formula and an estimate of age results.
The data for climatic regimes and soil textures were given values based on an
arbitrary scale for statistical analyses in the initial study. Climatic regimes are theoreti-cal
constructs derived from the combined influence of precipitation and temperature
on soil development. Rainfall and temperature affect soil development in several ways.
With increased rainfall, carbonates and clay are leached from the soil and organic
decomposition increases. For every 10o centigrade rise in temperature, the speed of
chemical reaction increases by a factor of two to three times. Soil texture, the descrip-tion
of the size and percentage of individual soil particles, affects soil development by
regulating the diffusion of moisture and atmospheric gases. The preliminary study
revealed that the variability in the OCR was the result of the interdependent dynamics
of several environmental variables. However, the climatic regime and soil texture
heavily influenced the variability in the OCR reading. (Click on the link below for the full article)
Douglas S. Frink
While few people would argue that the biochemical decomposition of organic
matter is independent from the environmental influences of heat, moisture, and O2, it
has been argued that the process of carbonization renders organic matter inert to these
influences (Dowman, 1970). The research leading to the development of the OCR-dating
procedure demonstrates that C, whether in the form of fresh plant litter or
charcoal, is subject to biochemical decomposition. Archaeologists who work in environments
conducive to biochemical decay are familiar with this fact. Cultural features
containing charcoal are common at recent open-air surface archaeological sites in the
dynamic mesic and thermic environmental regimes. Few, if any, such features are
found on early Holocene and late Pleistocene Period sites in similar contexts. Cultural
features containing charcoal from these early periods are found only under conditions
where the effects of the environment on the charcoal have been minimized. Caves and
rock shelters protect features from heat and humidity, and deeply buried features are
preserved by the reduction in available O2. Open-air surface areas expose archaeological
sites to the full impact of the environment. Older, exposed sites lack visibly identifiable
features due to the biochemical decomposition of charcoal.
(Click on the link below for the full article)
The OCR Carbon Dating procedure,developed by the Archaeology Consulting Team,
measures the site-specific rate of biodegredation of organic carbon,either as soil humic
material or as charcoal.The biological recycling of organic carbon is fundamental to
nearly all biological systems on this planet.While some forms of organic carbon,such
as fresh organic matter,are quickly recycled,other more resistant forms,such as hu-
mus and charcoal,are recycled at a much slower rate.This recycling follows a linear
progression though time when considered within the site-specific context,and in-
cludes the factors that influence biochemical degredation of organic carbon.Charcoal
and soil humic material,once thought to be inert,are biologically recycled at a slow
but measurable rate. (Click on the link below for the full article)