[Terrapreta] Terra Preta - not just about charcoal in soil

[David Yarrow]

yes, soil which is tightly managed and abused by conventional agriculture and annual crop monocultures will gradually deplete soil minerals and carbon.

but soil that is loosely managed and allowed to revert to a perennial system with full biodiversty will regenerate, recover and increase fertility.

one reason is because living soil not subject to routine annual plowing to rip up root systems.  this perennial soil develops a complex of root systems that penetrate far deeper into subsoil.  over the course of decades, the natural partnerships amongst this diversity of plants will increase soil fertility, in large part by drawing deeper mineral sources to the surface.  this biological diversity of plants creates several layers of dense networks of roots, organic matter and living biomass, including mycorhyzae, mycellium, bacteria, fungi, and more microbes to hold and recycle minerals in and on the soil surface.

taproots and other deep roots mine minerals and bring them up to the surface to grow new leaves, stems, flowers and seeds.  when these deep-rooted plants die or drop their leaves, their minerals and carbon is blended into the shallow root zone and held in the soil's most superficial systems for nutrient recycling among soil microbes and plants.  

common dandelion has a deep taproot to reach into and mine minerals in subsoil, and lift them to the surface as a thick rosette of leaves.  as a medicinal herb, dandelion is recognized as a mineralizer, and a good source of calcium, in particular.  so, to me, a field thick with dandelions is mineral-deficient soil, specifically calcium, and nature has deployed one of its most efficient mineral miners to begin pumping minerals up into the shallow root zone and spreading them around within reach of ordinary plants.  after very few years, dandelions will have done their work, and their populations will shrink.

or you could spray them with herbicide, broadcast lime and plow, all the while burning fossil fuel, and thus refuse to allow nature's intelligent natural succession of biology restore balance and completeness to the soil.

another reason is a similar selective specialization among micro-organisms.  micro-nutrients are required to build specialized molecules that regulate metabolic pathways -- their particular complex geometry of electron shells and valence states make enzymes, vitamins, hormones, specialized proteins, DNA, and regulatory biomolecules.  certain bacteria specialize in specific micro-nutrients and biomolecule synthesis.  my favorite illustration of this is vitamin B12 bacteria, but a better known one is iodine and the thyroid gland, which is why all supermarket salt is iodized.

but more relevant to gross soil fertility and productive capacity is nitrogen, next most important organic mineral after carbon.  in any perennial plant community, nitrogen is extracted from the air and fixed into stable, soluble chemistry by bacteria that live in cool, moist, dark soil.  these bacteria are not loners, but must live in communities, where they trade their special services for other requirements of life.  these interdependencies among soil organisms can't be poured out of a bottle or bag like an "instant" organization.  a period of time is required for bacterial diversities to get assembled, and then form functional communities.

enzymes for nitrogen-fixation require certain trace elements, including molybdenum and cobalt.  through extended, interlocking symbiosis, a soil ecosystem will locate and deliver such hard-to-find trace elements where they are needed.  translocating, assembling and using micro-nutrients among a microbial biomass may take nature a few months, or perhaps two or three years.  

in the long course of evolution, the entire family of legumes cultivated a specialized functional relationship to the family of nitrogen-fixing bacteria -- a clear example of symbiosis.  legumes provide nodules on their roots where these bacteria can proliferate and concentrate.  legumes feed the bacteria certain minerals, and sugar they make from sunshine, CO2 and water; the bacteria feed plants nitrates to make into amino acids and proteins.

nitrogenous bacteria also form symbiosis with other plants and microbes, not just with legumes.  so, what works in the perpetual heat and moisture of the tropics will have its adaptations to the short growing season and sandy soils of the northeast US.  certain nitrogenous bacteria thrive in aquatic ecologies, where they convert animal waste (ammonia & urea) into nitrates.  in aquaculture and aquaria, these bacteria are cultured on charcoal or gravel filters as a key part of the water purification system.

my main point here is that it takes a lengthy period of time to develop the biological and ecological complexities required for a fully fertile, stable soil.

and therefore, terra preta and modern machine & chemical farming are incompatible.  the traumatic annual disruptions of conventional farming systems assure the soil ecology will never get itself organized.  unless modern farming can give up annual plowing and ecocidal chemicals, it remains anti-thetical to terra preta strategy and biology.

David Yarrow
"If yer not forest, yer against us."
Turtle EyeLand Sanctuary
44 Gilligan Road, East Greenbush, NY 12061
dyarrow at nycap.rr.com
www.championtrees.org
www.OnondagaLakePeaceFestival.org
www.citizenre.com/dyarrow/
www.farmandfood.org
www.SeaAgri.com
 
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if one only remembers to turn on the light."  
-Albus Dumbledore
  ----- Original Message ----- 
  From: Sean K. Barry 
  To:  terrapreta at bioenergylists.org 
  Sent: Monday, October 01, 2007 11:36 AM
  Subject: Re: [Terrapreta] Terra Preta - not just about charcoal in soil


  I do not see that the nutrient content can be maintained, as each harvest of the corn cobs will deplete the nutrients and the charred stover will add nothing new beyond what was there when the crop sprouted minus the nutrients in the cobs.  So, the overall nutrient stock in the plot should deplete over time.

  Regards, SKB
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