permaculture

["robscott@freeshell.org" <robscott@freeshell.org>]

I took the Grow Biointensive Introductory Course with John Jeavons this 
spring. Having become familiar with the hearsay about the double-digging 
method, I wanted to hear Jeavons make the case for it himself. I was 
impressed by the thoroughness of the research they've done out there in 
Willits, California, as well as other places such as Mexico and Kenya.

The Biointensive system is designed to meet human needs on the smallest 
piece of land with minimal or no inputs. That's why annual vegetables and 
double digging (on-site human labor) are emphasized. They grow crops for 
calories and carbon (for compost) and aim for self-reliance with minimal 
input.

The double-digging makes sense where there are old, deep, clay soils. In 
these areas, crop growth can be severely limited by lack of oxygen to the 
roots, and double digging ensures that any area can become productive 
right away by improving drainage.

Here in Illinois, there are more than 10 million acres with drainage pipes 
installed to create the same effect in America's agricultural heartland. 
Most of America's corn, soy, and wheat comes from fields with deep 
drainage, comparable to double dug beds. What Jeavons did is develop a 
small scale system for communities, and kept track of what worked and what 
didn't, so that people with limited land and clay soil could have a hope 
for self reliance in vegetables using simple tools, seed-saving, and 
compost. As he said to me: if you can get better results without double 
digging in your area, do a comparison and let's publish the data.

Areas with less than 10" of soils don't really count against this 
system, Mitch, because they don't have deep anaerobic soil dynamics. Rock 
isn't soil. The design principle, if you will, is getting oxygen to plant 
roots, not only water. In some areas this won't be a major issue. Sandy 
soils, for instance. The issue is oxygen. Double-digging is just one 
method.

Rob
Urbana, IL