* the higher levels of soil microbial diversity and activity can lead to
weed and disease suppressive soils, through mechanisms that are beginning to
be understood. These mechanisms are no more "universally reliable" than
pesticides, but with the benefit of new insights and management methods, are
likely to become more reliable, much cheaper, and clearly safer (see Chapet
7 in "Pest Management at the Crossroads" for several examples; www.pmac.net).
* again, greater soil organic matter and biological activity makes it
possible for the farmer to tie up and cycle more nutrients and water in the
soil. While plants growing in such soils rarely go through the remarkable
growth spurts possible when a soil is treated with a high dose of N and
often irrigation water (the combination that produces those mammoth,
deformed-looking and typically tasteless strawberries), a slower growing and
maturing plant can nonetheless often reach just as high percentage of its
genetic yield potential. In conventional systems, there are advantages to
fast growth (better return on capital; multi-cropping; get the crop off
before the impacts of the methyl bromide are gone, etc), but these
"advantages" are inherently derived from the system in which such practices
are used, JUST AS in an organic system, things that might seem to
conventional growers as disadvantageous (never getting N levels above 25ppm,
e.g.), turn out to be part of system strengths. Systems are, afterall, more
than the sum of their parts.
* sustainable/organic systems rest upon building soil quality and tilth,
which promotes healthy root development. Much research in the U.S. has
shown clearly that full and healthy root systems are the source of much of
the profitability advantage on sustainable/organic farms, compared to
nearby, otherwise similar conventional farms, especially in years with less
than normal rainfall. Fuller root systems are more efficient in extracting
from the soil whatever N/P is to be had, and available moisture. This
impact is perhaps most dramatically evident (and unmistakeable) in the
research in the Pacific Northwest involving wheat root diseases (which cause
stunted root systems and poor yields despite increases in N/P levels).
(Anyone wanting to learn more can read any of the many
papers/addresses/books by Dr. James Cook, an ARS plant pathologist in
Pullman, Washington).
In sum, the advantages of farming systems that build soil quality
(organic matter content, lack of compaction, high levels of microbial
diversity and activity) in contrast to farming systems that do the opposite,
are fuller and more healthy root systems that can more efficiently extract
available nutrients and water from the soil; protection of roots and growing
plants from pest pressure through various, often complex microbial
biocontrol mechanisms; and; providing plants a chance to develop, perhaps
more slowly, but more fully in accord with its genetic
characterisitics/potential and the ability of its environment to provide
essential production inputs (light, nutrients, and water but WITHOUT
accompanying high levels of pest pressure and weed competition).
Charles (Chuck) Benbrook e-mail: benbrook@hillnet.com
Benbrook Consulting Services Voice: 202-546-5089
409 First Street S.E. Fax: 202-546-5028
Wasington, D.C. 20003