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PULLMAN – 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, Regents professor of soil science and lead author of a paper recently published in the PLoS ONE online journal. “We also show you can have high quality, healthy produce without resorting to an arsenal of pesticides.”
Reganold will talk about the strawberry study between 11 a.m. and 1 p.m. Friday, Sept. 3, on the Science Friday radio program. It is part of the Talk of the Nation program on Northwest Public Radio’s news station, heard at 1250 am in Pullman.
The program draws 1.3 million listeners.
The study is among the most comprehensive of its kind, analyzing 31 chemical and biological soil properties and soil DNA from 13 conventional and 13 organic farms. In addition, the taste, nutrition and quality of three strawberry varieties grown on these commercial fields were scrutinized and tested.
“There is no paper in the literature that comprehensively and quantitatively compares so many indices of both food and soil quality at multiple sampling times on so many commercial farms,” said Reganold.
Reganold’s previous studies of “sustainability indicators” on farms in the Pacific Northwest, California, British Columbia, Australia and New Zealand have appeared in the journals Science, Nature and Proceedings of the National Academy of Sciences.
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 featured in the study used the ozone-depleting methyl bromide, a chemical 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.