. 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