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A Comparison of Organically and Conventionally Grown Food
What are the Benefits?by Eric Sideman, Ph.D., MOFGA Director of Technical Services
When I started to write this article, I couldn’t help thinking about the quote from an election campaign a few years back that went, "It's the economy....". Well, here I have come up with, "It's the environment...". Even though numerous studies confirm that many people believe that organic foods are healthier than conventionally produced foods, this has not been conclusively demonstrated by scientific studies. The problem is that too many factors confound the issue, and that the distinction between what is conventional and what is organic is not always clear. Many conventional farmers are implementing very good agricultural practices that are at the heart of organic farming, and some organic farmers may be doing no more than substituting natural products for synthetic ones while still implementing poor farming practices.
So, market-oriented studies of organic versus conventional have a real problem in that the origin of the samples cannot be identified. The producers are not known and hence researchers have no information about the practices by which the food was produced. The quality of the product clearly depends on the condition of the soil, the cultural care during growing, the kinds of spraying and the post harvest handling. Conventional growers vary considerably in all of these practices. And, although we don’t like to think so, there is plenty of variation among organic growers too, especially when much of the organic food sold in stores is not certified organic.
Comparison of side by side farms may be better because the practices are known, but the problem here is that the results apply only to the specific location and particular farming situations. In order to make general statements and to examine various orientations of organic and conventional farming, a very large, and probably unmanageable, number of tests would be required. To date, only very few side by side studies have been done.
A recent literature review by Woese et al. (1997) summarized the results of over 150 studies and showed the difficulty of comparing the two types of food production by looking at the product. Some food quality differences were noted, and I will mention them below, but after reading the article I see that the major differences between organic and conventional production relate to agronomic benefits and environmental impacts. These have been demonstrated because it is easy to point at good or poor farming practices and report their effects on the farm and the surroundings.
Generally, comparative studies reviewed in the Woese paper do not show any differences in pesticide content or nutritional value between organic and conventional products. This is true for cereals and cereal products. One difference that was supported in the literature is that organic wheat and rye products seemed to have lower protein content. I think this is probably a warning for organic producers to provide more nitrogen to their crops, because lower protein may result in poorer baking properties.
Regarding nutritional content, organic potatoes had higher levels of phosphorus and potassium, but no differences were seen in any other minerals or vitamins, including vitamin C. No conclusions about mineral contents could be drawn about differences between organic and conventional production of other vegetables either. There was a higher level of vitamin C reported in organic vegetables by about half of the 27 studies. So again, although there seems to be a trend it is hard to make a clear statement.
Regarding pesticides, the Woese review did conclude that there is a trend toward lower levels of pesticide residues in vegetables and vegetable products from organic production. Residue levels in the range between the detection limit and the maximum limit were reported for many of the conventionally produced vegetables, but rarely did any exceed the maximum statutory amounts. Only traces were found in organic vegetables, probably from environmental contamination. Similar results are reported for fruit.
Despite the limited nutritional differences supported by the scientific literature, organic food is clearly different from conventional in some notable characteristics. One is nitrate concentration. Woese et al. report that nitrate concentrations were clearly lower in vegetables from organic cultivation. Higher nitrate levels in conventionally cultivated crops or in those treated with mineral fertilizers were found mainly in leaf, root and tuber vegetables.
Although not included in the Woese study, conventional and organic foods clearly differ with respect to genetic engineering. The only way to be assured that food does not contain transgenic material is to buy certified organic.
Another topic that is receiving attention since the Woese article is pathogenic E. coli . Recent research at Cornell University has shown that cows fed mainly hay generate less than 1% of the pathogenic E. coli 0157:H7 found in the feces of grain-fed animals. Since organic ruminants tend to be fed more pasture and hay, organic livestock production potentially reduces the risk of pathogenic E. coli 0157:H7 infection. Furthermore, only certified organic farms are required to follow guidelines on waiting periods between manure applications and crop harvests to enhance food safety. Conventional farms, which use the majority of manure in this country, are not regulated at all with respect to manure use.
In my opinion, the greatest benefit of organic food is that organic production is based on farm practices that improve the soil of the farm and have minimal environmental impact. Such practices are mandated by organic production standards of certifiers, including the new proposed USDA rule. These practices include the prohibition on toxic synthetic chemicals that interrupt natural biological activity on the farm and may contaminate the ground. Fertilization on organic farms is based on crop rotation with legumes; compost; and regulated manure use. In contrast, fertilization on conventional farms may be based on unregulated manure use and synthetic chemicals. Synthetic chemical fertilizers are very energy expensive to produce and are difficult to use without contaminating the surrounding environment. Overuse of manures may be just as risky as synthetic chemical fertilizers, which is why organic certifiers enforce regulations on the amount of manure used and the time of application. Conventional farms are not regulated at all with respect to their synthetic chemical fertilizer or manure use.
Conventional agriculture may produce cheap food, but the external costs are very high. External costs include:
Woese, K., D. Lange, C. Boess and K. Werner Bogl, 1997. A Comparison of Organically and Conventionally Grown Foods--Results of a Review of the Relevant Literature. J. Sci. Food Agric. 74: 281-293.
About the author: Eric is MOFGA’s "extension agent." You can direct your questions about farming or gardening to him at the MOFGA office in Unity, or at firstname.lastname@example.org.
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