[permaculture] arid soil building

Dieter Brand diebrand at yahoo.com
Fri Dec 4 17:57:03 EST 2009

A dirt mulch is a well known technique used in dry land farming.  Heavy clay soil with low organic content has the tendency to dry out rapidly through capillaries forming in the clay.  The capillaries first transport humidity from the subsoil to the topsoil where it evaporates when it reaches the surface.  This continues until the clay *closes down* and doesn’t give off any more humidity to plants or to the air.  It still holds some humidity, but to the eye and for all practical purposes it is stone dry right down to the solid rock.  To prevent this evaporation, farmers first plough the field to produce a fine powdery top layer of soil (the dirt mulch) which means the capillaries from the subsoil don’t reach the soil surface and humidity is preserved in the subsoil for plants to use.  After irrigation or rain, the top layer needs to be hoed to prevent capillaries from forming in the soil crust.  The hoeing is only shallow to a depth of about 3
 to 6 inches.
Dieter Brand

--- On Fri, 12/4/09, Robert Waldrop <bwaldrop at cox.net> wrote:

What do you mean by "dirt mulch"?

Bob Waldrop, Oklahoma City


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