Healthy soil and sustainable growing

[Doug Willhite <drwillhite@earthlink.net>]

If you haven't been to Gene Logsden's blog you don't know how much  
fun you're missing!

Go here: http://thecontraryfarmer.wordpress.com/2010/01/02/all-our- 
soil-problems-solved-you-bet/

I think of Gene as the Andy Rooney of homestead-farming.

doug

http://chihuahuavalley.net

All our soil problems solved. You bet.
by Gene Logsdon

Relax, fellow farmers and gardeners. From now on everything is going  
to come up roses and sunshine. A magical and mysterious soil has been  
discovered deep in the Amazon (roll of drums, please) that will  
double and triple your yields and grow tomatoes as big as  
basketballs. Not only that but this soil will sequester enough carbon  
to keep us warm through the entire coming ice age. Lean your ear  
close while I whisper to you the magic phrase. Shhhhh. Terra preta.  
Dark earth. In the ancient cities of El Dorado days, it meant  
salvation. For awhile.

And now you can have some for your very own garden.

I am sort of making fun of terra preta because of the money-mongers  
who would like to make a fortune selling the stuff to gullible  
Americans, but the story of this miracle soil really is amazing. Deep  
in the South American rain forest area there really are deposits of a  
mysterious soil as much as six feet deep in some places spread over  
thousands of acres. That of itself might not be remarkable, but  
anthropologists are almost certain that all of it, or at least most  
of it, was created by human beings in the centuries before Columbus  
blundered upon the American continent.

Actually there’s nothing much magical about terra preta beyond the  
fact that it was man-made. Archaeologists reason that it is the  
burned, or charred municipal wastes of lost civilizations whose  
populations numbered in the millions and who are now thought to have  
been very advanced. The black, sometimes brown, soil was made by  
burning food wastes, human and animal excrement, and a whole lot of  
wood. It is full of broken pottery shards which lends credence to the  
idea that it was originally municipal waste. Farmers who own deposits  
of it today still grow good crops on it.

Deposits of terra preta stand in stark contrast to the normal rain  
forest soil around them. The latter is shallow and of low fertility.  
Evidently, far back in history, humans figured out how to supplant  
these natural soils with terra preta, composting and burning their  
own wastes to do it. In that way they were able to meet the food  
demands of rising populations.

This magic soil is mostly charcoal, and scientists and entrepreneurs  
are making a new version of it which they call bio-char. You can find  
some for sale on the Internet. You can make your own by adding  
activated charcoal to compost or potting soil. The charcoal does make  
the soil more porous so that it will hold more nutrients and keep the  
soil more stable. It also will sequester carbon if you don’t subtract  
all the carbon emission created by burning wood to make charcoal.  
Soil scientists tell me not to get too excited about terra preta  
because while it is much richer than the rain forest soils of the  
Amazon region, our soils, especially our rich cornbelt soils, don’t  
need charcoal, or bio-char, at least not yet. In fact, the hot  
temperatures necessary for making bio-char volatilizes all the  
nitrogen out of it and so nitrogen fertilizer has to be added to it,  
sort of like when you use wood ashes for fertilizer. It is really  
more practical, soil scientists say, to make one’s own terra preta by  
composting organic wastes into humus in the usual way. Do it for ten  
thousand years and you will end up with deposits of mysteriously rich  
terra preta six feet deep.

So what happened to those marvelous farmers of the past who figured  
out how to make soil that could support high human populations? Many  
historians say it all ended because of the diseases that Spanish  
explorers brought to the American continent. But that is disputed  
because civilizations rose and fell several times before any  
Europeans arrived. It seems more probably that population growth kept  
outrunning the society’s ability to make more terra preta fast enough  
to keep up. The population crashed, then slowly increased again, with  
a new civilization adding more terra preta before it too over- 
populated, and that process repeating itself unto death do us part.

The Chinese with their careful utilization of all organic wastes were  
able to sustain a very high population density for something like  
forty centuries. But eventually they felt forced to make laws  
limiting family size to one child.

Terra preta does lead to all kinds of speculation. Maybe we should  
start char-burning our landfills to make fertilizer. Some municipal  
waste burning is being tried to generate energy. Maybe in 15  
centuries our mountains of trash will be rich deposits of terra preta  
type soils. And all those humanoid creatures from other planets will  
be poking through them and wondering how our lost civilization could  
have been so smart as to create something so wonderfully fertile.