Six encouraging conclusions on the impacts of organic farming on soil quality and the nutritional content of food were reached by a panel of scientists participating in a February 13, 2009, symposium at the annual meeting of the American Association for the Advancement of Science (AAAS). The symposium was entitled “Living Soil, Food Quality, and the Future of Food” and was held as part of the largest scientific meeting of the year that spans all disciplines. The AAAS meeting was held this year in Chicago, IL.
The panel of scientists included Dr. Preston Andrews, Washington State University, Dr. Jerry Glover, The Land Institute, and Dr. Alyson Mitchell, University of California-Davis. The “Living Soil, Food Quality, and the Future of Food” symposium was organized and sponsored by Washington State University and The Organic Center, based in Boulder, CO. The presentations made by the three panelists and other symposium information are posted on The Organic Center website (http://www.organic-center.org/science.events.php?action=view&report_id=148).
Panelists Statement of Conclusions
A growing body of sophisticated research over the last decade has compared the impacts of organic and conventional farming systems on soil and food quality. Based on this body of research, some of it carried out in field experiments and laboratories, we can conclude that:
1. Studies of apple production demonstrate that organically farmed soils display improved soil health as measured by increased biological diversity, greater soil organic matter, and improved chemical and physical properties. Enhancement of soil quality in organic apple production systems can lead to measurable improvements in fruit nutritional quality, taste, and storability.
2. Organically farmed tomatoes have significantly higher levels of soluble solids and natural plant molecules called secondary plant metabolites, including flavonoids, lycopene, and Vitamin C. Most secondary plant metabolites are antioxidants, a class of plant compounds that have been linked to improved human health in populations that consume relatively high levels of fruit and vegetables.
3. Organic farming can, under some circumstances, delay the onset of the “dilution effect.” In hundreds of studies, scientists have shown that incrementally higher levels of fertilizer negatively impact the density of certain nutrients in harvested foodstuffs, hence the name, the “dilution [of nutrients] effect.” Specifically, tomatoes grown with organic fertilizers maintain constant concentrations of beneficial phenolic secondary plant metabolites and antioxidants, even as fruit grow larger, whereas concentrations of these same beneficial compounds decline with increasing fruit size when the same tomato cultivar is grown using conventional methods and fertilizer.
4. Studies of 27 cultivars of organically grown spinach demonstrate significantly higher levels of flavonoids and vitamin C, and lower levels of nitrates. Nitrates in food are considered detrimental to human health as they can form carcinogenic compounds (nitrosamines) in the GI tract and can convert hemoglobin to a form that can no longer carry oxygen in the blood.
5. The levels of secondary plant metabolites in food appear to be driven by the forms of nitrogen added to a farming system, as well as the ways in which the biological communities of organisms in the soil process nitrogen. Compared to typical conventional farms, the nitrogen cycle on organic farms is rooted in substantially more complex biological processes and soil-plant interactions, and for this reason, organic farming offers great promise in consistently producing nutrient-enriched foods.
6. Organic soil fertility methods, which use less readily available forms of nutrients, especially nitrogen, improve plant gene expression patterns in ways that lead to more efficient assimilation of nitrogen and carbon in tomatoes. This improvement in the efficiency of nutrient uptake leaves plants with more energy to produce beneficial plant secondary metabolites, compounds that promote plant health as well as human health.
Commenting on the well-attended symposium, Dr. Preston Andrews said, “The work we reviewed over the last decade points directly to two major scientific challenges. First, we need to understand more fully how soil biological communities process nutrients and communicate to plant roots in order to promote improved quality in organically grown crops. And second, we need better tools to help organic farmers fine-tune their production systems in order to maximize the soil and nutritional quality benefits of organic farming.”
The three presentations made at the AAAS symposium are accessible on The Organic Center’s website (http://www.organic-center.org/science.events.php?action=view&report_id=148).
For further details on the work of Dr. Preston Andrews, visit http://www.hortla.wsu.edu/people/andrews.html.
The research program of Dr. Alyson Mitchell is described on her website at http://mitchell.ucdavis.edu/.
Dr. Jerry Glover’s research at the Land Institute is accessible at http://www.landinstitute.org/vnews/display.v.
The Organic Center’s website contains a section on “Nutritional Quality” at http://www.organic-center.org/science.nutri.php. Reports and presentations posted include the Center’s March 2008 comparison of nutrient density in organic and conventional foods, and the “State of Science Review” entitled “Still No Free Lunch: Nutrient Levels in U.S. food supply eroded by pursuit of high yields.” This September 2007 report describes in detail the genetic and physiological basis of the dilution effect.
About The Organic Center
The Organic Center is a 501c3 non-profit organization founded in 2002. The Organic Center helps consumers, policy makers, researchers and the media understand the benefits that organic products provide to society. The Center highlights credible, peer-reviewed scientific research about the human health and environmental benefits of organic farming. Through our work, we hope to promote the conversion of more farmland to organic methods, thereby bringing the benefits of organic food and farming to a growing number of people and a greater share of the American agricultural landscape. For more information visit www.organic-center.org, tel 303.499.1840.