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permaculture - Re: [permaculture] CEC, Biochar and Soil Remineralization with quarry rock dusts. | an interesting and useful reply

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  • From: venaurafarm <venaurafarm@bellsouth.net>
  • To: permaculture <permaculture@lists.ibiblio.org>
  • Subject: Re: [permaculture] CEC, Biochar and Soil Remineralization with quarry rock dusts. | an interesting and useful reply
  • Date: Mon, 20 May 2013 16:10:54 -0400



On 5/19/2013 3:13 PM, Lawrence F. London, Jr. wrote:

Michael Astera of http://soilminerals.com writes:
How does one "build good soils"? Serious question.

I frequently see soil test reports with a CEC below 7meq. A CEC of 7 is
necessary in order to hold onto sufficient Ca, Mg, and K to provide
minimum optimal levels of those minerals (minimums would be 750 ppm Ca,
100 ppm Mg, 100 ppm K). Those amounts need to be there even if the soil
can't hold onto them. If they are added for the growing season and the
soil can't hold them what the plants don't take up will likely by washed
away by precipitation and irrigation.

How to build CEC? By adding or growing large quantities of organic
matter, or high CEC clay, or humate ore, or biochar. Adding enough
compost may or may not be practical, and in a hot climate may not be
do-able at all. High CEC clay is heavy, and the best, Calcium Bentonite,
is expensive and hard to find. Humate ore is expensive and can only be
used in small quantities. Biochar is often the most practical answer if
it can be obtained or made at a reasonable cost.

Rock dusts & CEC:

Apart from remineralizing your soil would CEC be improved with
application of large (medium or small) quantities of non toxic,
environmentally clean, rock dusts from quarries, i.e. siltation pond
fines? Reading the MSDS freely supplied by each rock quarry would tell
you the array of minerals in their product and the percentage of each
one. You could then decide which fines you want to use and how much you
want to apply. The material is usually free; you pay for trucking or
haul it yourself. Rent a skid loader for 4 hours and spread it out on
your fields or gardens when soil is not moist or wet, i.e. very dry, to
reduce compaction from loader or truck. These quarries are under close
scrutiny by the EPA because the large water flow from the siltation
ponds affects the local watershed, ecosystems, streams, rivers and
creeks. I have two piles of dust at the edge of my field to use in top
dressing or making potting soil. Rainfall has washed small amounts o
these powders, pyrophyllite and granite, across my lawn and dirt
driveway. Grass and white and red clover growth in these areas is
incredible, never before seen, especially the white clover. Melilotus
alba or tall white sweet clover has also benefited from the rock dusts.
Every deciduous hardwood tree seed that falls on this land seems to
sprout and grow at a record rate. Using a skid loader I mixed clean,
aged, black, natural cow straw manure with equal amounts of a mix of
quarry rock dusts, a small proportion of bagged and bulk mineral
amendments (idaho rock phosphate, tennesee rock phosphate, florida
colloidal and rock phosphate, greensand, azomite) then applied to areas
where I wanted to establish gardens. I have photos of all this inluding
pix of farm implements used. BTW a Yeomans keyline plow is a must have
for a small farm. This was an expensive project that I could only afford
to do once in a lifetime so I laid down a lot of materials and a lot of
intensive, deep tillage, created a lot of tall wide raised garden beds,
sold off all the equipment and now only use no or minimum till garden
methods and top dress as needed to maintain soil fertility with compost
made from weeds in the gardens, bagged chicken manure, granulated
seaweed, rock phosphate, azomite and greensand.

Michael Astera of http://soilminerals.com replies to my question:

"It sounds like you did a wonderful job of mineralizing your soil, but what you added won't necessarily add CEC.

Exchange capacity is the ability of components of the soil to hold onto minerals via a static electrical charge. A soil particle with a positive + charge can hold a negative ion (an anion) like NO3- nitrate; a negative - charge can hold a positive ion (a cation) like K+, Potassium. See
http://soilminerals.com/Cation_Exchange_Simplified.htm

Soil components with high CEC, cation exchange capacity, include some clays, humus and humate ore, and charcoal. Humus, humates, and charcoal also have significant AEC, anion exchange capacity. (AEC is not usually measured on soil tests.)

Rock dusts generally have little or no exchange capacity because they don't have significant static electrical charge. Florida soft rock phosphate is an exception, because it contains a good amount of high-CEC clay. Limestone powder, Calcium carbonate, has effectively zero exchange capacity; ditto for basalt, granite, etc no matter how small the particles.

Adding fresh rock dusts can easily skew a soil test to read too high in exchange capacity because Ca, Mg, K, Na etc will be etched from the rock particles, rather than only from exchange sites. One can tell if they are likely to have that problem by pouring vinegar on a dry soil sample; if it fizzes considerably that means high levels of freely available cations, especially Calcium.

The best way to find out the actual CEC of the soil would be to test a sample that has not been amended with rock dust."

Michael A
http://soilminerals.com

Biochar:

My experience with applying charcoal from my outdoor wood fired cook
stove/water heater was very good. The particles ranged in size from dust
to 1" chunks plus a little ashes. I spread the charcoal over an
adjoining weedy area. Plant growth there has been phenomenal for the
past 5 years.

If there is a way to make large quantities of biochar using readily
available biomass,, tree trimmings, etc., i.e. materials on site,
without generating more than a minimum of creosote-laden smoke, then
this should become a standard gardening procedure to follow when
materials need to be recycled and soil amendments are needed. Biomass
and tree trimming could be divided between biochar production,
Hugelkulture mound gardens and compost making. I assume that there is a
near pollution-free method of making biochar that mostly exudes steam;
anyway it should be possible with the right equipment configured and
operated properly.





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