Hello Roberto and all others following this thread...
>On 04 May 00 03:15:13, Roberto Verzola wrote:
>>I presume that by "conventional" farmer, you mean one that regularly
>>uses chemical fertilizers and pesticides. If you said "more quantity",
>>I can understand (at least for a while, they can). But I wonder how
>>their produce can be of better quality than those who don't use
I just finished looking through the proceedings of a conference which
included a number of papers directly related to the relationship between
soil management and crop nutritional quality. The conference "Agricultural
Production and Nutrition" was hosted by the School of Nutrition Science and
Policy at Tufts University in 1997 and the editor of the proceedings was W.
Lockeretz (Tufts School of Nutrition). He gave me a copy of the proceedings
last fall and had extras at that time.
I concur with Bart that it is very difficult to achieve a genuine organic
system as a treatment in a replicated randomized block experiment. However,
I know that there are long term experiments in progress that include both
organic systems and conventional systems such as the Rodale Farming Systems
Trial (FST) as well as the Rodale Compost Utilization Trial (CUT), where
the organic systems have developed higher soil quality as measured by a
wide range of soil parameters. It seems hard for me to believe that Rodale
has not collected some crop nutritional quality data for these 2
experiments being that "healthy soil = healthy food = healthy people" is
one of the Rodale mantras...
As I stated previously when this thread last made an appearance on this
list, I am much less interested in studies that consider "organic" and
"conventional" cropping systems to be monolithic entities, than I am in
studies that look at the relationship between specific soil properties and
crop nutritional quality. I know that Dr. Dave Douds has used the Rodale
CUT to look at the impact of different soil amendment regimes on crop root
infection with mycorrhizal fungi. There was a study in the American Journal
of Alternative Agriculture several years ago that showed a positive
relationship between mycorrhizal infection and micronutrient content of
wheat. It would be great to know whether the Rodale CUT treatments show
this same relationship.
Roberto asked "I wonder how their produce can be of better quality than
those who don't use
Bart made some good points in his response. I can't imagine that he meant
to imply that low rates of fertilizers or pesticides were required to
achieve nutritional quality... rather that the judicial use of such
practices disqualifies one from selling "organic" crops but does not
necessarily nullify the cropping system benefits of crop rotation, cover
crops, use of compost...etc.. on crop nutritional quality.
I would add that if soil is very infertile... depleted in macronutrients
(e.g. P) as is the case in much of the developing world... it is very
likely to produce more nutritious crops (in addition to higher yield) if
judicious rates of P fertilizer are added. This point is made in one of the
papers presented in the Tufts conference proceedings "Relationship between
Soil Quality and food quality in Ghanaian soils". A farmer that uses a
little purchased commercial fertilizer is likely to produce crops that are
of higher nutritional quality than a farmer that does not remedy
fundamental soil nutrient deficiency problems.
Lastly, in addition to considering variation in inherent soil properties as
a source of variability in crop nutritional quality, we certainly need to
consider variation between crop cultivars. We can't compare organic carrots
of variety A with conventional carrots of variety B and expect to have
meaningful results. This point is made in another article in the Tufts
proceedings "Exploring the potential to enhance dietary iron from a green
leafy vegetable" which discusses natural variability between cultivars in
bioavailable iron content.
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