On Wed, 03 May 2000 08:34:37 -0500, Russ Bulluck wrote:
>In order to conduct the experiment (and accurately report results from said
>experiment), the fewer variables that are dependent (i.e. under control of
>the experimenter) the better. When results like these are compared from two
>different fields then there will always be a question of soil property
>differences. However, if the experiment is run side-by-side
>(organic-synthetic, in a randomized complete block, or split plot design)
>then the experiment carries much more weight by eliminating soil differences
>that could be said to cause the differences (as Joel so eloquently pointed
>out).
I must disagree fairly strenuously. First, the sorts of 4-4-4 studies
you propose (4 treatements, 4 replicates, 4-ever) are better suited to
simple testing of a theory or the evaluation of a series of mono-valent
treatments. Once you start overlapping treatments, the statistics can
get squirrelly in a big hurry. Organic production (properly done) is a
decidedly *multi-valent* system of overlapping treatments, wholly
unsuited, IMO, to the sorts of research typically handed over to grad
students in hopes they can cobble together a gramatically coherent MSc
thesis out of it.
Side-by-side comparison of conventional methods with
simple-substitution organic analogues is a meaningless make-work
project, producing results that are at best useless, and (more often)
misleading. Effective comparisons must be at a much larger scale, and
over a longer term, preferably within a single soil / climate regime.
The same experimental design (for evaluating organics) will produce
markedly different results on the Ultisols of Mississippi, the
Mollisols of Iowa, and the Spodosols of Quebec.
Properly done, organic production *creates* demonstrable soil property
differences, for example:
a) Increased soil organic matter (thereby increasing cation exchange
capacity, soil moisture retention, aeration, and wet aggregate
stability).
b) Different qualitative organic matter profiles ( providing much
greater fresh organic matter, more labile organic matter, and
proportionally reduced lignins and other non-interactive organic
matter).
c) These differences in turn produces changes in the microbial
assemblage, both in absolute numbers (many orders of magnitude
greater), the mix of different types (in most climates, higher
bacteria:actinomycetes:fungus ratios), and the turnover time of organic
matter.
Against that background, differences in fertility practices *will*
produce differences in mineral levels and (often) flavor. I know this
from several years of commercial-scale organic production experience,
even comparing the results of my own system to itself five years
previously.
I suspect that the only practical way around the statistical problem of
trying to evaluate a systems approach is to compare significant numbers
of a wide variety of *locally grown* samples from several different
regions. California organic vs. California conventional. Massachusetts
organic vs. Massachusetts conventional. Ditto for the US southeast, the
Canadian Prairies, the US Midwest, and so on.
The studies done so far have been quite inconclusive. Partly because of
regional differences --- comparing a Massachusetts organic carrot
against its conventional California counterpart is meaningless --- but
mostly because even within a region there are huge variations in the
professionalism of organic growers. Most are not especially good
growers, particularly when it comes to mineral fertility management.
Studies like the Australian one (I haven't seen the original work) may
be one dab in a large Pointilliste painting. They are *descriptive,*
rather than prescriptive. It's a nice little something to cite in
commercial publicity, but please don't make the mistake of generalising
its conclusions or of assuming they are in any way definitive.
The only thing definitive about the whole question is that we are
undertaking the equivalent of trying to solve for 8 or 10 unknowns
while working with about 3 equations. As they used to say in New
England, "You can't get there from here."
Really good organic farmers will grow better quality produce than most
conventional farmers. Really good conventional farmers will grow
better quality produce than most organic farmers. Leave it at that, and
let's concentrate on removing the abundant mental and emotional
barriers that keep most farmers (organic and conventional) from getting
any better at what they do.
Bart Hall
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