permaculture

[Mark <mpludwig@facstaff.wisc.edu>]

At 11:33 AM 11/30/02 -0700, you wrote:
> . I think it's also an explanation of why in
> *some* conditions plowing works (perhaps occasionally or short term)

Plowing, or tillage in general, oxidizes humates (and other things), this 
can give the soil a burst of available nutrients liberated from the 
humates.  Same situation with highly available N.  This can yield a heck of 
a burst of productivity for crops in the short run, though once you start 
to run out of active humates this effect drops off.  Good shallow tillage 
(6 -10 cm) that incorporates and mixes in compost, green manure etc.  can 
give the soil life a boost from feeding them, certainly a valuable 
technique, especially when restoring degraded soils or growing intensive 
crops.  Tillage is an important tool, but like so many tools it is over used.
M


Mark P. Ludwig
Poultry Research Lab
University of Wisconsin -Madison
608-262-1730 WK
608-846-7125 HM