From http://web.archive.org/web/200103100...r/boshart2.htm
"Mozafar, A. 1994. Enrichment of some B-vitamins in plants with application of organic fertilizers. Plant and Soil 167:305-311.
Organic food suppliers often claim that organic foods grown on soils with natural fertilizers have a better nutritional value than foods grown with inorganic fertilizers. Although past studies, such as those published by Gray and Daniel in 1959 or by Leclerc and colleagues in 1991, have shown that organically grown produce had more vitamins, it was unclear if the plants synthesized them or got them from the soil. In order to test the origins of vitamins in plants, this researcher selected vitamin B12 for study. This was because plants cannot manufacture it but microorganisms can. In addition, large amounts of B12 are found in animal manure, a commonly used organic fertilizer. This study looked at whether plants, specifically soybeans, barley, and spinach, grown on soils amended with pure B12 or B12 in manure would have a higher B12 content than plants grown with inorganic fertilizers. All plants contained a minimal amount of B12 in the inorganically fertilized soil.
Barley showed a threefold increase of B12 in the harvested grain in both the pure B12 treatment (10.8 ng/g dry weight) and the manure treatment (9.1 ng/g dry weight). In spinach leaves, B12 increased twofold in the manure treatment (17.8 ng/g dry weight) and 34-fold in the pure B12 treatment (235 ng/g dry weight). Soybeans had a similar, but not as dramatic trend. In addition, soil samples in fields receiving manure over several years contained more B12 than those only receiving inorganic fertilizers. These results show that B12 levels can be increased in organically grown food through the use of manure fertilizers. This is good news for vegetarians, who often have trouble getting enough B12 in their diets. It is also good news for consumers who buy organic food because of its better nutritional value. While this preliminary trial does seem to indicate that vitamins can be absorbed from the soil, more studies should be done with other vitamins to confirm these observations.
Abstract Author: Margaret Boshart, 21 October 1997. "
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