Food Sleuth: Helping people think beyond their plate

The virtues of soil

By Melinda Hemmelgarn, M.S., R.D.

Photo © Dan Hemmelgarn Melissa Hemmelgarn with tomatoes.

Sir Albert Howard appreciated the virtues of soil. That’s "soil," as in your basic garden-variety earth that many of us treat like dirt. The British botanist believed that humus-rich soil, the miraculous medium from which our nourishment springs forth, pulsates with life and forms the basis of public health. In the 1940s, Howard said: "The real arsenal of democracy is a fertile soil, the fresh produce of which is the birthright of nations."

Today, many scientists agree with Howard’s groundbreaking idea that soil microorganisms are the unsung heroes of healthy environments. Earthworms, bugs and the millions of microbes in a single handful of soil break down organic matter, such as leaves, decaying plants and animal manure and release the nutrients plants need for optimum growth.

Native farmers in Barbados and India taught Howard about the critical nature of soil and the interdependence of soil, plants, animals and humans. Think of it this way: We need healthy soil to produce nourishing food, which protects the health of animals and people. Healthy people create vibrant communities.

Howard realized decades ago that chemical fertilizers and synthetic herbicides and pesticides deplete the soil, which leads to public health problems, including disease and environmental destruction. Yet according to the National Pesticide Use Database, in 2002 more than 675-million pounds of pesticides were applied to crops in the United States alone.

Thankfully, the University of Kentucky Press has recently reprinted Howard’s The Soil and Health. Originally published in 1945, the book largely inspired our modern-day organic movement.

The time has come to re-think Howard’s words, especially in light of recent research showing what’s in organically grown food might matter as much as the missing synthetic pesticide and herbicide residues. For example, research at the University of Minnesota and the University of California-Davis found that organic farming methods yield produce with higher levels of nutrients, especially over time, as soil has a chance to accumulate organic matter. Researchers compared tomatoes harvested over a 10-year period from two matched fields, one organic and the other conventional (which included commercial fertilizers).

Over time, health–protecting antioxidants, called flavonoids, increased significantly in the tomatoes grown in the organic fields but not in the conventionally grown tomatoes. The researchers explained that higher quality soils cycle nutrients more efficiently, making them more available to plants when they need them. Other studies have found higher levels of vitamin C, iron and magnesium in organic crops, lower levels of potentially harmful nitrates and better taste. In general, organic production methods can raise healthful antioxidant levels in fresh produce by about 30 percent.

The benefits of soil-enhancing organic farming methods extend beyond nutritional composition. For example, at Iowa State University, horticulture and agronomy researcher Kathleen Delate discovered higher yields, increased profitability and steadily improved soil quality in organic over conventional fields. Improved soil structure protects against erosion and improves the soil’s ability to hold onto water during a drought. The United Nation’s Food and Agriculture Organization recommends organic farming to help fight hunger and tackle climate change.

Unfortunately, we tend to progress in a linear fashion, without reflecting on the wisdom published or spoken decades before us. Andrew Kimbrell, director of the Center for Food Safety and author of Fatal Harvest: The Tragedy of Industrial Agriculture, suggests we question that approach. "When we speak of progress, we should ask ourselves: Progress towards what?"

Today’s conventional agribusiness has replaced agriculture, leading us down a narrow and dangerous path toward shrinking biodiversity, weakened resilience and unhealthy soil and water. Luckily for us, the recent groundswell of organic demand might save our soil and our society.

Melinda Hemmelgarn, M.S., R.D., is a registered dietitian, advocate for sustainable food systems, and Food and Society Policy Fellow. She’s based in Columbia, MO. ©Food Sleuth 2008 .