March 26, 2007
Need more reasons to eat organic? Studies have found that organic farming is highly preferable to conventional agriculture in terms of its effects on the environment. A yearlong experiment, conducted in an established apple orchard on a 4-acre site in the Yakima Valley of central Washington, used some trees raised with conventional synthetic fertilizers; others grown organically without pesticides, herbicides or artificial fertilization; and a third group raised on integrated farming, which combines organic and conventional agricultural techniques.
One goal of the study was to compare the amount of nitrogen leaching into the soil. When present in excess of the amounts needed by plants, nitrates percolate through the soil, contaminating surface and groundwater supplies. The researchers measured nitrate leaching during the entire year and found it was 4.4 to 5.6 times higher in the conventional treatment than in the organic treatments, with the integrated treatment in between.
The research team also compared the amount of nitrogen gas released into the atmosphere. Nitrogen compounds from fertilizer can enter the atmosphere and contribute to global warming. Air samples collected in the orchard after the fall and spring fertilizations revealed that organic and integrated soils emitted larger quantities of an environmentally benign gas called dinitrogen (N2) than soils treated with conventional synthetic fertilizer.
Modern conventional farming practices have also led to nutrient-poor food. The mineral content of vegetables has dropped significantly over the last few decades. Today, you need to eat almost twice as many carrots and three times as much broccoli to get the same amount of calcium you would have received from one serving of these vegetables in 1950. The lesson is clear: organically grown foods are the better choice to promote the health of both ourselves and our planet.
Kramer SB, Reganold JP, Glover JD, Bohannan BJ, Mooney HA. Reduced nitrate leaching and enhanced denitrifier activity and efficiency in organically fertilized soils. Proc Natl Acad Sci U S A. 2006 Mar 13; [Epub ahead of print] PMID: 16537377
Davis DR, Epp MD, Riordan HD. Changes in USDA food composition data for 43 garden crops, 1950 to 1999. J Am Coll Nutr. 2004 Dec;23(6):669-82. PMID: 15637215