New Cutting-Edge Book On Amazonian Soils
A landmark book has been published on terra preta (Amazonian dark earths), the carbon-rich soils developed by ancient civilizations in what was once thought to be a pristine wilderness. Dedicated to Dutch soil scientist Wim Sombroek (1934-2003) who was the first modern investigator of terra preta, Amazonian Dark Earths: Wim Sombroek’s Vision by William I. Woods, Wenceslau G. Teixeira, Johannes Lehmann, Christoph Steiner, Antoinette M.G.A. WinklerPrins, and Lilian Rebellato (Editors) is a compilation of the latest, cutting-edge studies in this fascinating and important multi-disciplinary field.
Amazonian soils are principally laterites [here], deeply weathered red clays lacking in most soil nutrients. Millions of years of rainfall have leached out everything but iron (hence the red color) and aluminum. Essential plant nutrients such as calcium, phosphorus, and potassium are nearly missing. Amazon vegetation subsists on itself, the thin humus of decaying plant matter being the only source of key metallic oxides.
Except where there is terra preta, and it’s close cousin terra mulata. Terra preta is deep, rich, fertile black soil that occurs in patches on bluffs along the Amazon and its tributaries. Terra preta is filled with charcoal, ash, mulch, bones, and pottery shards! It is potting soil made from organic matter transported to the sites in pots! These anomalous soils are anthropogenic: people made them.
[Dr. William] Denevan (2001:116–119) has argued that in pre-Columbian times the use of stone axes made long-fallow shifting cultivation very inefficient, and as result probably uncommon until the European introduction of metal axes. Previously, soil fertility must have been maintained and improved by frequent composting, mulching, and in-field burning, making semi-permanent cultivation possible with only brief fallowing. Over time these activities could have produced fertile, self-sustaining dark earths.
Dark earths may occupy 0.1% to 0.3%, or 6,000 to 18,000 km2, of forested lowland Amazonia (Sombroek and Carvalho 2002:130). Because their densities vary greatly within subregions and almost no systematic survey has been accomplished within Amazonia, variations in density projections of an order of magnitude are to be expected. The dark earths occur in a variety of climatic, geologic, and topographic situations, both along river bluffs and in the interior, with depths sometimes exceeding 2.0 m. Individual patches range from 1 ha or so to several hundred hectares. — from Chapter 1, Amazonian Dark Earths: The First Century of Reports by William I. Woods and William M. Denevan
Rather than a pristine, untrammeled, unoccupied wilderness, Amazonia has been home to people for thousands of years. The residents were agriculturalists who modified soils in order to grow corn (maize), squash, beans, fruiting palms, gourds, pineapples, cotton, arrowroot, and many other cultivated fruits, nuts, tubers, and fibers.
Terra mulata is brownish soil that generally surrounds patches of terra preta. It is not quite as rich and has fewer artifacts, and is even more widespread than terra preta. In theory, terra mulata is the accidentally improved soil adjacent to the deliberately improved soils, or else it is terra preta in the making. In either case, anthropogenically altered soils are in strong contrast to the unaltered laterites, and cover a combined area the size of France.
One of the key elements of terra preta is charcoal, lately termed “biochar”.
Vegetation actively withdraws carbon from the atmosphere and stores it as organic matter. Biochar is created when organic matter is heated without oxygen and it contains twice the carbon content of ordinary biomass (Lehmann 2007). Biochar is much more resistant to decay and can store carbon for centennial timescales (Lehmann et al. 2006). The addition of biochar to the soil was part of the creation of ADE [Amazon dark earths] (Neves et al. 2003). This has lead some to speculate on the viability of a biochar carbon sequestration industry which would reduce atmospheric greenhouse gases (Marris 2006; Sombroek et al. 2002) and improve soil fertility (Lehmann et al. 2003; Glaser and Woods 2004). — from Chapter 14, Locating Amazonian Dark Earths (ADE) Using Satellite Remote Sensing – A Possible Approach by J Thayn, KP Price, and WI Woods.
Biochar is touted as a “solution” to the global warming “problem.” I disagree. But biochar is definitely a valuable soil amendment because carbon binds to and stores the metallic oxide nutrients essential to plant growth. The addition of charcoal as well as organic detritus helped to create and sustain terra preta over centuries.
Amazonian Dark Earths: Wim Sombroek’s Vision is a wonderful account of the history and science of anthropogenic soils. The book is as rich as terra preta in literary as well as scientific writing.
Note 1: for more of this review see W.I.S.E. Colloquium: History of Western Landscapes [here].
Note 2: My own garden here in the Willamette Valley contains ancient human-altered soil. There is quite a bit of charcoal. Here are some flakes, knives, and scrapers that have roto-tilled to the surface.
by Erich J. Knight
I have a friend with a farm in the Willamette Valley with a long riparian border. He told me he has found black dirt in spots along the high bank. He attributes it to Indian encampments and perhaps fires, camas ovens, and latrine holes or wholesale scat dropping in the same place over millennia. His evidence, of course, is points and tools that come up in plowing and working that ground. It is in blueberry plants, with grass middles and headlands, so whatever is there now, will be there for some time.
My own garden contains ancient human-altered soil. There is quite a bit of charcoal. I posted above a pic of some flakes, knives, and scrappers that have roto-tilled to the surface.
By the way, Erich, the Holocene Optimum occurred 8,000 years ago. The planet has been gradually cooling ever since.
There is no credible evidence that CO2 is warming the planet; in fact, the significant cooling of the last ten years coupled with rising CO2 levels is strong evidence that atmospheric CO2 has no effect whatsoever on global temperature change.
So while amending soils with biochar may increase nutrient storage capacity, it will have absolutely no effect on climate change.
Perhaps the most important lesson to be learned from Amazonian Dark Earths: Wim Sombroek’s Vision is that there is no such thing as wilderness. “Wilderness” is a modern conceit without foundation in the real world.
It might be nice if the folks who are bouncing off walls trying to “save” the planet would grasp onto reality for a change. I don’t mean to curb your enthusiasm, but if it was directed toward stewardship based on reality, it might do a lot more good.
by new_biochar_land
The world is a great place, but it is falling apart and we all are responsable for this. Be responsable now and try to make it better.
Biochar, one of the newest option can contribuate to atmospheric CO2 reduction. Find out more:
[snip]
The Biochar Revolution is exactly what it says !
Reply: Dear NBL, the world is not falling apart, no thanks to you and your “revolution”.
PS - the ability to spell, and/or use a spell checker, seems to have eluded you. It could be because you are a moron. Perhaps you should attempt to educate yourself to a 5th grade level before you foment any more revolutions, if possible, which is doubtful but perhaps not impossible. You see, I hesitate to carry the banner for revolutions led by morons. No offense.
by Foo Furb
Mike: You are being harsh. new_biochar_land may sound like an idiot, but beeing a bat spellr dusn’t necessarily make him a moron.
Besides, if Biochar says it is Revolting, as n_b_l claims is “exactly” the case, then who are you to be arguing with charcoal?
(And, yes, the world IS a “great place!” There is always some room for agreement, even among the most disparate of opinions.)
Reply: Foo, I was perhaps too harsh on NBL. You should see the spam I get, though. I mostly delete it, but NBL’s comment was amusingly illustrative of typical spamish qualities, and so I let it through as a joke. You would think that a spammer trying to sell merchandise would take the time to polish his message. Not so in NBL’s case. Chances are he (or she or it) is a spam robot, not an actual human being.
Next time I won’t be so forgiving, which made me look harsh, and just consign the spam to the spam bin, which is harsher but nobody sees me do it.
by YPmule
I love the photo of the “scrappers” Mike. (winks)
Reply: Fixed. Thank you.
PS — The editor job is open. It’s all work for no pay, but you are hired!!!!
Biochar Soil Technology… Husbandry of whole new orders of life
Biotic Carbon, the carbon transformed by life, should never be combusted, oxidized and destroyed. It deserves more respect, reverence even, and understanding to use it back to the soil where 2/3 of excess atmospheric carbon originally came from.
We all know we are carbon-centered life, we seldom think about the complex web of recycled bio-carbon which is the true center of life. A cradle to cradle, mutually co-evolved biosphere reaching into every crack and crevice on Earth.
It’s hard for most to revere microbes and fungus, but from our toes to our gums (onward), their balanced ecology is our health. The greater earth and soils are just as dependent, at much longer time scales. Our farming for over 10,000 years has been responsible for 2/3rds of our excess greenhouse gases. This soil carbon, converted to carbon dioxide, methane, and nitrous oxide began a slow stable warming that now accelerates with burning of fossil fuel.
Wise Land management: organic farming and afforestation can build back our soil carbon.
Biochar allows the soil food web to build much more recalcitrant organic carbon, (living biomass and Glomalins) in addition to the carbon in the biochar.
Biochar, the modern version of an ancient Amazonian agricultural practice called Terra Preta (black earth, TP), is gaining widespread credibility as a way to address world hunger, climate change, rural poverty, deforestation, and energy shortages… SIMULTANEOUSLY!