Commercial organic farms have better fruit and soil, lower environmental impact, study finds
ScienceDaily (Sep. 2, 2010) — Side-by-side comparisons of organic and conventional strawberry farms and their fruit found the organic farms produced more flavorful and nutritious berries while leaving the soil healthier and more genetically diverse.
“Our findings have global implications and advance what we know about the sustainability benefits of organic farming systems,” said John Reganold, Washington State University Regents professor of soil science and lead author of a paper published in the peer-reviewed online journal, PLoS ONE. “We also show you can have high quality, healthy produce without resorting to an arsenal of pesticides.”
The study is among the most comprehensive of its kind, analyzing 31 chemical and biological soil properties, soil DNA, and the taste, nutrition and quality of three strawberry varieties on more than two dozen commercial fields — 13 conventional and 13 organic.
All the farms in the current study were in California, home to 90 percent of the nation’s strawberries and the center of an ongoing debate about the use of soil fumigants. Conventional farms in the study used the ozone-depleting methyl bromide, which is slated to be replaced by the highly toxic methyl iodide over the protests of health advocates and more than 50 Nobel laureates and members of the National Academy of Sciences. In July, California Sen. Dianne Feinstein asked the EPA to reconsider its approval of methyl iodide.
Reganold’s study team included Preston Andrews, a WSU associate professor of horticulture, and seven other experts, mostly from WSU, to form a multidisciplinary team spanning agroecology, soil science, microbial ecology, genetics, pomology, food science, sensory science, and statistics. On almost every major indicator, they found the organic fields and fruit were equal to or better than their conventional counterparts.
Among their findings:
The organic strawberries had significantly higher antioxidant activity and concentrations of ascorbic acid and phenolic compounds.
The organic strawberries had longer shelf life.
The organic strawberries had more dry matter, or, “more strawberry in the strawberry.”
Anonymous testers, working at times under red light so the fruit color would not bias them, found one variety of organic strawberries was sweeter, had better flavor, and once a white light was turned on, appearance. The testers judged the other two varieties to be similar.
The researchers also found the organic soils excelled in a variety of key chemical and biological properties, including carbon sequestration, nitrogen, microbial biomass, enzyme activities, and micronutrients.
DNA analysis found the organically managed soils had dramatically more total and unique genes and greater genetic diversity, important measures of the soil’s resilience to stress and ability to carry out essential processes.
Pundit’s thoughts:
Over at Biofortified there has been some debate in the comments section about on the merits of this study
I thought this article was really interesting and had some really cool unexpected findings (e.g. shelf life). When I started to think about it, the results became less surprising. The strawberries, tomatoes, peppers, grapes and herbs in my garden are always better than those from the store or even fresh-picked conventional goods. My soils are rich with compost and the plants are sprayed for pests minimally, if at all. I guess I could have guessed the results of this study before I read it.
It would have been nice to see the results after each received a standard post-harvest treatment. I wonder how these results would translate to the store? That would have been nice to see. Also, I wonder if yields were markedly different? This is a good study in a great journal and I hope it stimulates more of the same.
Dr. Steven Novella wrote about this study, and found a little more ambiguity in the comparisons than the press release lets on. http://www.theness.com/neurologicablog/?p=2285
Nevertheless, an improvement is still an improvement. I wonder what the crucial factors end up being? What part of the organic management system changes things, and what does not have an effect? Most organic-conventional studies don’t pick these details apart, which is unfortunate because conventional farmers can adopt organic practices if they know that it is beneficial.
This is not a very impressive showing.
For instance, a comparison of 13 conventional and 13 organic samples resulted in one organic sample tasting better. This leaves open the possibility that 12 conventional samples tasted better than organic!
Higher concentrations of antioxidants is meaningless. While widely touted as beneficial, antioxidants have no proven health benefits, and are actually implicated in some diseases, such as diabetes. [1]
The notion of ‘unique genes in soil’ having the claimed effect is nonsensical — DNA does not behave that way.
The position of ‘health advocates’ and Nobel laureates on the use of methyl bromide is quite irrelevant to strawberry quality, etc. This detour from science into pro-organic evangelism signals, however, that the authors have a particular interest.
Shelf life may be related to dry matter content, but could also be related to how samples were selected. And, overall, organic researchers are not known for honesty.
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1. http://www.reuters.com/article/idUSTRE5955Z620091006
The antioxidant argument always bothered me too. At a meeting last year a berry breeder showed that he was able to increase the antioxidants in his berries by 50% after years of laborious and expensive breeding. I asked, “Why not just get people to eat two berries and you’ve exceeded that point with a lot less work”.
I guess that’s my point. If the berries are superior then that’s great. But if the plant produces one berry then the increases are meaningless.
The microarray experiments are no real surprise either. Basically they did a nice job proving the obvious. Now I hope they go back and look at principle components and determine what facet of the study led to the effects they see.
It is a good study in many regards. The media love affair with organics really helped promote it. That’s good. I think it is great that people get excited about growing higher quality food with less impact to the environment.
At a brief glance it looks to me that the organic berries are more stressed than the conventional – that’d explain increased anti-oxidants alongside the increased anthocyanin (although as berries aren’t even remotely in my area of knowledge perhaps this is a poor assumption – anthocyanin in my mind conures up images of unhappy plants) hoping to have time to really give the paper a good look over the next few days – reading the figures is all I’ve managed thus far.
Kevin, Ewan,
It’s well-known that plants under stress, such as from herbivory and other stresses, produce toxins in order to protect themselves.
The notion of consuming these toxins as ‘beneficial’ is weird.
Don’t forget, tobacco produces nicotine to protect itself. There’s not too many people who tout nicotine as a health food.
I’m not impressed. Or rather, I’m impressed by the obvious tilt towards organic in the commentary. And I fully agree with Steven Novella (the link provided by Karl) that the data do not support the authors conclusions.
Take this:
“Using hedonic/intensity ratings [by the way on… half a strawberry per treatment], consumer-sensory panels found organic ‘Diamante’ strawberries to be sweeter and have preferable flavor, appearance, and overall acceptance compared to conventional ‘Diamante’ berries (Table 3). Organic and conventional ‘Lanai’ and ‘San Juan’ berries were rated similarly. Sensory results of sweeter tasting ‘Diamante’ strawberries were confirmed by higher soluble solids content measured in the laboratory (Table 5).”
Well, according to table 3, conventional ‘San Juan’ was rated better than its organic counterpart, and ‘Lanal’ the same. So, it’s a draw. Table 5 equally suggests a mixed picture.
The data are also puzzling. Strawberry fruit were collected in June and September 2004 and April, June, and September 2005, and on three varieties, yet, for instance, the survival distribution curves of rot tests (a pedestrian’s experiment) are only given for June and September 2004 and for two varieties, ‘Diamante’ and ‘San Juan’. In one and the same table, e.g. table 1, you can find data per variety and other in aggregated form. May be there is a good reason for this, but this does not sound well for a study in an area where opinions run rather high.
And I find it particularly irritating to see the word “significantly” at every corner. A difference may be statistically significant and yet it may pertain to something that is totally insignificant. Kevin put it nicely: eat two berries instead of one (actually, in his example, it was one half). I presume you would also make a saving thereby.
The biggest deficiencies of the study are perhaps, one, that we are only provided sketchy information on the crop husbandry itinerary, two, that we have no indication whatsoever on the agronomic and economic results and, three, that there is no analysis of pesticide residues. Lists of products, pesticides or fertilisers (Table S2) are not good enough; and what about irrigation? And what’s the point of having strawberries that are found better quality – although this is not obvious from the data nor from a common sense interpretation of the differences that have been measured (see comments above…) – if the agronomic and socio-economic cost is a halved crop (mind the “feeding the nine billion by 2050”, although we are talking here of a luxury food, not a staple)? And how sustainable is a cropping system that requires 20 to 24 metric tons of urban waste compost every two years, liquid fish emulsion, bloodmeal and feathermeal? And what about rotenone residues?
I gave up on the very quickly on the soil quality part. It seems that many articles comparing conventional and organic agriculture cannot exist without this type of comparison. It is a matter of course that a soil that receives double the amount of compost than another will have a richer microbial life. And it is also a matter of course that farmers produce crops and make their money from the crops.
I noted, however, that conventional soils fared pretty well, despite the chemical fumigations. Interestingly, organic soils were found to have more nitrates… The study is silent about this.
On a final note, I am particularly puzzled by the statement that “organic strawberries may have been more resistant or avoided infection by means other than fungicides (e.g., systemic-acquired resistance)”.
And last but not least, Karl, thanks for the link. Steven Novella’s analysis is very pertinent, and the comments are very interesting as well. I was particularly impressed by the number and quality of the comments that do not praise organic farming to the skies.
If I’m remembering the tables right the only significant difference was in the comparison noted in the study – non significant differences don’t count as a win. 2 draws and one marginal win do however still suggest a draw rather than a convincing difference.
More fertilizer/compost more nitrates – doesn’t particularly matter what form of nitrogen you apply (at least in corn fields – so I’m assuming this maxim carries over to any non-aqueous environment (ammonium is the predominant form for rice paddies) according to colleagues) – it pretty much all ends up as nitrates (bacteria do the job of converting both ammonium and urea to nitrate) – which would explain increased dry matter etc rather well (and increased sweetness to be fair – more nitrogen –> more chlorophyll (both quantity and length of time you have xphyll for –> more photosynthesis –> more fixed carbon (which is where you get your sweetness and dry matter from)
As a nitrogen centric guy I’d be interested in how much N ended up in the plants and how much runoff there was – nitrate is incredibly mobile.
I guess I really need to read the paper rather than responding to comments from those who have… wonder how many odd looks I’ll get reading scientific papers in the delivery room…
Wait, delivery room?
Congratulations!!!
(mentally add internet sparkles, please)