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Coal and Soils

Dan Kilminster
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I have a property in the central west of New South Wales. The property run between two hills, one is mostly sandstone, the other is mostly shale. In a few areas there are exposed coal seams which have eroded to produce incredibly dark soils. There are large healthy Acacias and Eucalyptus growing in these soils.

I have been unable to find any useful infomation about soils of this type. I was wondering if there were any dangers associated with growing plants or running stock over these types of soils.

Im also interested in whether the coal or the dark soil would be a useful soil ammendment similar to biochar.
Bryant RedHawk
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Location: Vilonia, Arkansas - Zone 7B/8A stoney, sandy loam soil pH 6.5
chicken dog forest garden hugelkultur hunting toxin-ectomy
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A lot will depend on what type of coal it is. High sulfur content will create acidic soil ( sulfur + H2O = Sulfuric acid ), so if you want blueberries or other acid lovers, that type of soil would be great (to a point).

Some coal seams are low sulfur and those might make a soil similar to volcanic soils. These are very mineral rich soils that grow many types of plants very well.

To find out, grab some samples and head to the local university or extension service for a test.

In Kentucky there are coal seams such as you mention, many plants love that soil.  Most of this "surfacing" coal is low sulfur coal.
Cattle are run on it, as well as goats and hogs. Not to mention the fine Deer population that feeds on plants and trees in these areas.

eric koperek
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TO:  Dan Kilminster
FROM:  Eric Koperek = erickoperek@gmail.com
SUBJECT:  Coal verus "Biochar"
DATE:  PM 6:00 Monday 19 September 2016

(1)  Coal and charcoal are NOT the same.

(2)  Please do NOT use coal or any coal derivative as a soil amendment.  You can ruin your fields permanently.

(3)  We Germans did most of the original research on use of charcoal as a soil amendment, and coal ash and wood ash as fertilizers.  This research dates back to the early years of the 19th century = 1800's.  So we know more about this subject than anyone else.

(4)  Coal and coal ash contain various quantities of sulfur and heavy metals.  Excess sulfur lowers soil pH significantly reducing crop yields.  Heavy metals in sufficient concentration poison agricultural soils.

(5)  Acidic soils make aluminum much more soluble.  Aluminum toxicity is a problem for crops in both temperate and tropical regions.  Modern medical research has linked aluminum toxicity to diseases of the heart and nervous system.

(6)  Correcting overly acidic soils requires large = expensive amounts of lime, charcoal, or vast amounts of organic matter (to buffer soil pH).

(7)  Correcting soils contaminated by heavy metals is even more costly.  Often, the contaminated earth must be removed = vastly expensive.

(  Consequently, it is better to avoid soil contamination because environmental cleanup is so very costly.

(9)  Beware of municipal sewage (contains heavy metals) and chicken manure (may contain arsenic) as these fertilizers might also contaminate your fields just like coal or coal ash.

(10)  Agricultural charcoal is NOT a fertilizer.  Charcoal is a soil amendment.  There is a difference.  Charcoal has a vast amount of surface area where chemical reactions can take place.  (1 gram of powdered charcoal has the equivalent surface area of a football field).  Nutrients, water, and soil bacteria "stick" to charcoal surfaces.  Charcoal acts like a chemical sponge balancing soil pH and preventing nutrients from leaching out of the soil.

(11)  For adjusting soil pH:  1 part of powdered agricultural limestone = 2 parts agricultural charcoal = 2 parts of wood ashes by WEIGHT.  You can substitute these materials freely depending on cost and availability.

(12)  Do NOT apply "raw" agricultural charcoal to gardens, fields, or potting soils.  Raw charcoal is like a magnet that draws nitrogen out of the soil and holds it tightly so it is unavailable for plant roots.  Translation:  Your crops will get all yellow and sickly and yields will be very poor.  Application of raw charcoal can cause complete crop failure.  (Charcoal is like a vacuum cleaner; it is so powerful that it sucks nearly all of the nitrogen out of the soil and can hold it for a year or longer).

(13)  Charcoal must be composted before use.  Mix charcoal with equal parts of animal manure by VOLUME then compost not less than 30 days before application.  Turn compost every 2 or 3 days.  Composted charcoal is safe for plants and will not cause nitrogen deficiency.

(14)  Up to 40% composted agricultural charcoal can be mixed with greenhouse potting soils.  Adding more charcoal decreases plant growth.

(15)  To amend problem soils add up to 10% agricultural charcoal by VOLUME to make Terra Preta = Dark Earth (similar to the charcoal amended dark earths of the Amazon, Africa, and Southeast Asia).

(16)  Agricultural charcoal is expensive = much more costly than limestone or wood ashes in most areas.  Consequently, it is NOT economic to add charcoal to most agricultural soils in temperate or tropical climates. 

(17)  Charcoal amendment is most effective on sands (such as land reclaimed from the sea), and highly leached plastic clays typically found in tropical rain forests.

(1  Soils weathered from exposed coal seams are very rare and usually quite limited in extent.  Contact your Provincial agricultural university for more information about the properties and management of soil series on your farm.

(19)  Nota Bene = Note Well:  "Biochar" means BIOLOGICAL CHARCOAL = charcoal made from something alive = wood or agricultural wastes.  COKE = carbon made by baking coal in an air-tight furnace should NEVER be used for agricultural or medicinal purposes.

ERIC KOPEREK = erickoperek@gmail.com

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