> A debate exists in mainstream agriculture that
> large commercial organic practices do less to
> conserve soil than No-Till operations where chemical
> herbicides and insecticides/fungicides are used as a
> tool.
I wouldn't be surprised if certain mainstream farming operations do a
better job conserving soil, than do some organic farming operations.
> While it is true that No-Till does not employ the plow
> as do most organic operations, would it also true that
> these undisturbed soils are rife with residues from the
> chemistry used on them in the name of soil conservation.
"rife with residues" is pretty strong language. An acre-plow layer
contains roughly 2 million pounds of soil. It is hard to imagine that
spraying 2/3 ounce of Accent herbicide on the canopy interferes with
very much, especially since it has been designed to be highly selective
and biodegradable. Eptam (Eradicane) is an instructive case too.
Frequent use results in elabortion of soil biota that break it down in a
few weeks (rather than a few months), greatly reducing it's usefulness
as a herbicide. In fact, it is hard to think of examples, save the soil
sterilants and fumigants, of chemicals that really interfere with the
biology of the soil. Perhaps some of the high-powered soil
insecticides? (But the Big problem in practical agriculture is weeds!)
All cultural practices, including chemical applications must be treated
as individual cases, and stand or fall on their own merits. Rejecting
all chemical pest controls out of hand falls into the realm of aesthetic
considerations.
> I don't like to think that organic farming could be
> responsible for loss of topsoil, but it is. I like it
> less that No-Till is commonly combined with chemistry
> instead of a thoughtful policy of crop rotation to suppress
> unwanted biology.
Why not integrate all these tools? For example, Roundup resistant
soybeans are a neat trick, and solve many nasty weed problems, but
excessive use of Roundup will shift the weed population toward species
less susceptible to Roundup (maybe even select for resistance within
species). But this is true with any weed control practice, even tillage
and cover crops. The smart thing to do is to rotate weed control
practices in addition to crops. The new postemergence herbicides, and
herbicide/variety packages are additional tools to add to the system.
They should be examined individually for environmental safety, efficacy
and cost-effectiveness.
In all this, I believe that reduction in tillage is undeniably a good
thing:
1. Reduces fuel use and cost, and equipment needs
2. Reduces erosion, including mobilization of phosphorus and pesticide
residue
3. Reduces oxidation of soil organic matter
4. Reduces soil compaction
5. Probably interferes less with soil biota such as worms
Contrary to what BBacon seems to think, there has been extensive
research on this for many years. I did a few literature searchs,
restricting it to corn, to avoid an avalanch of hits. If anyone wants
me to send them the references let me know.
Reducing tillage causes problems too. For example, the emergence of
gray leaf spot in corn, and white mold in soybeans as major diseases are
consequences of reduced tillage. Many pest problems are controlled by
moldboard plowing. Well-targeted use of pesticides, and development of
pest-resistant plant varieties allows reduction in tillage, no doubt
about it.
I realize the absolutists on this list will come back at me with
arguments to completely remake the face of agriculture (and the world
economy). But presenting environmental responsibility as such an
extreme polarity (alternativism) is counterproductive. Ordinary people
tend to throw up their hands and dismiss the utopian vision as
impractical. We don't want them to dismiss, along with it, the
incremental ways they can help the environment right now.
Dale Wilson
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