I think that we are in agreement that there is a marked degree of
homogeneity among farmers in both how they grow corn and the
genetics of the corn they grow - right? And as you noted, this could
explain at the *macro* level the increasing CV's reported for US
crops, and Ontario crops, as yield increased.
If that is correct, then let's take a hypothetical group of 100
corn producers, all behaving about the same, responding to the same
extension info, the same fertilizer adverts, the same market
forecasts, and using the same genetic material. At the macro level,
the similarity in their responses could increase CV for yield at the
regional scale - right?
But if they are all behaving the same, then why would variance at the
*micro* level not be the same as at the *macro* level? I'd have
thought that micro would be different from macro only if the macro
was the integration of a number of differing micro-scale decisions -
but we've already accepted that corn producers are NOT behaving as
independent decision makers, but in a substantially homogeneous
fashion. Perhaps you can clarify this for me.
Your points about applying excess N as "good insurance" are well
taken, and have been very well documented. See El Hout and Blackmer
(1990. J. Soil and Water Conservation 45:115-117). I would reiterate
and expand, however, on my earlier point. "Reduced input" can be
taken to mean just conventional ag with less N - your point - or a
whole different way of looking at yield and N - e.g. holistically -
my point. I would suggest that risk management is an entirely
different phenomenon in the two "systems". Ann
Dr. E. Ann Clark
University of Guelph
Guelph, ON N1G 2W1
Phone: 519-824-4120 Ext. 2508
FAX: 519 763-8933
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