It is often said that organic agriculture is better for the environment. But these claims were hard to substantiate bucause there was little data on the subject. However there has been a recent study released by J. P. Reganold of Washington State University in which some of these effects were examined more closely. In this installment the primary WSU study is contrasted with a secondary in the form of a blog post titled "Berry Good For You" by Michelle Venetucci Harvey. The study took place in California USA and made use of several types of strawberry as a sample crop. The experiment was extremely well designed and the secondary source was well written and took into consideration nearly all the findings and related them with a reasonable degree of accuracy.
However there are several areas of the blog that were, to a degree, misleading. It seems that in some instances interesting points raised by the research were left out. Or that some points of interest in regard to the opinion were stressed while others were left out. There are several areas covered which have differences which include, nutrients of leaf and fruit, antifungal characteristics, soil DNA and consumer-sensory testing results.
The blog praises the organic berries for having increased antioxidants, ascorbic acid, and total phenolics, but down plays the conventional crops’ increased levels of phosphorous and potassium. While the study warns of the American diet becoming inundated with phosphorous, the potassium seems to be a valuable asset to be left out of the significance. There were also some polyphenols whose levels were similar between tests like quercetin and ellagic acid which may both have antioxidant properties which are being lauded. While the overall impression is encompassing, there are interesting details which are left out.
Also concerning nutrients, the study samples nutrient concentrations in the leaves of the plants. The findings revealed concentrations of phosphorous, potassium, and magnesium in conventional plants that were much higher than those grown organically. The study was clear that there is no conclusive research on foliage nutrient concentrations and their indications but this is a large difference in the tests and is given no mention in the blog nor is the increased concentration of nitrogen in the conventionally grown fruit.
There is a claim made by the blog that the organic plants were healthier than their conventional counterparts. This seems to be based on post-harvest fungal rot sampling done in the study. However the study looked at picked strawberry fruit which was placed in a moist sealed bag and incubated rather than the plants themselves. The plants do not seem to have been tested for fungal growth but rather the picked fruits and so the claim that the plants were healthier because of their fruit being more resistant to rot does not seem valid.
Another point of interest is raised when the blog firmly says that no fungicides were used on the organic fields. This is true in that the study did not permit the use of fungicides that target the grey mould being studied. However the organic fields were treated to a sulfur spray in order to control powdery mildew which is a fungus . Therefore the claim that no fungicides were used at all is clearly not true. There is not an impact of the sulfur fungicide on the study, but its use is denied by the secondary source.
The study also looked at consumer reception of the berries based on criteria such as appearance and flavor. Of the three types of strawberry grown, two were found to have little difference by the consumer-sensory panels while the third variety was favoured because of an increased sweetness which was scientifically confirmed. Of the panelists ninety-five percent preferred berries to be more sweet than tart, and while this may be reflective of the general population’s preferences it does not mean that the organic variety really taste better, only that it played into the preference for sweet fruit. However the blog makes several claims that the organic fruit tastes better. This seems to be at odds with the panel tests, a one out of three result does not overwhelmingly make the organic fruit better apart from the sweetness caused by increased soluble solids in the Diamante strawberries.
The topic of soil DNA was well reviewed by the blog and most of the important data were accurately relayed. There was some discrepancy where the study reported diminishing improvements in soil quality at the second test depth of the organic farms which was not mentioned in the blog but the overall trend in the soil quality was still better for the organic which was expounded by the blog. The study also identifies a large increase in soil gene biodiversity in the organic fields which is picked up by the blog. The study makes a note that some of this diversity may be redundant in the functional groups, but again this is not included in the blog in favour of praising the biodiversity and its shielding from change. Finally the study notes that the use of twice as much compost on the organic fields likely impacted the difference in microbial properties between the two methods of farming.
External validity is touched on in the blog, where it is commented on that this research only applies to strawberries at the moment. However this does not fully encompass the issue. In California the biocide fumigant methyl bromide is still used despite its use being restricted 1987 (the USA appealed for exception until a substitute is found). The study used conventional fields that had been using the fumigation techniques for at least five years and commented on the possible detrimental effect of this prolonged exposure on microbial life and soil DNA which the blog alludes to in its reference to methyl bromide. While other conventional farming methods may use similar biocides they may also be different, and comparing organic farming to conventional methods that use a substance which has been severely restricted for twenty years (Montreal Protocol 1987) might not be the best general statement for or against conventional methods in general. California is not representative of all conventional farming and in addition to the blogs call for more crop testing, more regions are also needed.
In reading the secondary source and its primary origin it seems logical and apparent that information is lost in condensing a study paper into a small blog or article. It also seems important to note that in this case the primary source supports the opinion of the secondary author which might not always be the case. And that the primary source information is being filtered through another author who may selectively omit parts of the study. This particular blog was very impressive in its relation of the detailed study results in an accurate and concise manner and shows that while some information may be omitted as the price of brevity the secondary source is a powerful was to disseminate scientific findings with the caveat that those findings should be investigated further if the article interests.
British Columbia Ministry of Agriculture and Lands (accessed 09, 23,10) http://www.agf.gov.bc.ca/cropprot/peppermildew.htm
Reganold JP, Andrews PK, Reeve JR, Carpenter-Boggs L, Schadt CW, et al. (2010) Fruit and Soil Quality of Organic and Conventional Strawberry Agroecosystems. PLoS ONE 5(9): e12346. doi:10.1371/journal.pone.0012346 http://www.plosone.org/article/info%3Adoi%2F10.1371%2Fjournal.pone.0012346
Venetucci Harvey, M. (2010, September 03). Berry good for you. Retrieved from http://www.grist.org/article/new-study-weighs-in-on-organicconventional-debate/