Soil Health - Organic Trade Association
Organic Trade Association
   twitter   facebook   linked In   rss

Soil Health


Organic agriculture builds the health of the soil, providing the foundation for healthy crops and a livelihood for good stewards of the land.

In order to be certified organic, crops must be grown on land free of prohibited substances for at least three years prior to harvest. Crops grown on land in transition to organic (during the first three years after switching from conventional farming) cannot be labeled as organic.

National organic standards require producers to use organic agricultural methods and materials that cover soil fertility, the application of manure, crop rotation, and composting. National organic standards prohibit the use of municipal solid waste and sewage sludge as compost ingredients.

Organic producers also must follow a National List of Acceptable and Prohibited Materials concerning pest control treatments, fertilizers and seed treatments that they use. All agricultural materials must be evaluated for their long-term effects on the environment and not simply whether they are synthetic or natural.

  • High organic matter content has a positive effect on soil physical properties. For example, soils with high organic matter content contain a greater abundance of water-stable aggregates and have a greater exchange capacity, which translates into better structure and water-holding and nutrient absorption capacities. Larger aggregates also slow organic matter degradation, producing a slowly mineralizing pool of nutrients.

    Organic matter also reduces crop attractiveness to insect pests.In fact, crops growing in soils receiving diverse organic matter inputs have been shown to be less attractive to some insect pests, as a result of a more nutritionally-balanced growth medium.


  • A University of Wisconsin-Madison study has shown composted manure can increase crop yields and disease resistance. In field trials at Harmony Valley Farms in Viroqua, researchers used an untreated control, composted goat manure, composted dairy cow manure, and a commercially available feather meal product mixed with soybean meal. The same field was used in both seasons, allowing observations on cumulative effects of compost applications in the second year. Researchers found dairy manure compost increased crop yields by an average of ten percent. Soil microbiology research found that the ratio of total fungal to total bacterial biomass was a strong predictor of yield.

Source: Center for Integrated Agricultural Systems, University of Wisconsin’s College of Agricultural and Life Sciences (phone: 608-262-5200).

  • A study of apple farming published in Nature found organic orchards can be more profitable, produce tastier fruit at similar yields compared to conventional farming, and be better for the environment. In the six-year study, John P. Reganold and colleagues (Jerry D. Glover, Preston K. Andrews, and Herbert R. Hinman) at Washington State University in Pullman farmed three experimental plots of Golden Delicious apples using organic, conventional, and "integrated" growing methods. Although the organic system took longer to reach profitability, it ranked first in terms of environmental sustainability, profitability and energy efficiency by the end of the study. Integrated farming, reducing the use of chemicals by combining organic and conventional production methods, came in second, with conventional farming last.
    Source: Nature 410:926-930 (April 19, 2001).

  • Organic farming enhances soil fertility and biodiversity, according to findings from a 21-year field trial initiated by the Research Institute of Organic Agriculture (FiBL) in Switzerland. Begun in 1978 in Therwil, Switzerland, the DOK trial compares the consequences of organic, biodynamic, and conventional farming systems in a randomized plot trial. According to the 16-page field trial report:
  1. "Fertilization in organic systems has a positive effect on the content of organic matter and helps to avoid soil acidification;"
  2. "Organic soil management improves soil structure by increasing soil activity, thus reducing the risk of erosion;"
  3. "Organic management promotes the development of earthworms and above ground arthropods, thus improving the growth conditions of the crop. More abundant predators help to control harmful organisms (pests);"
  4. "Organic crops profit from root symbioses and are better able to exploit the soil;"
  5. "Organic fields accommodate a greater variety of plants, animals and microorganisms."

Source: FiBL Dossier: Organic farming enhances soil fertility and biodiversity, August 2000.

  • Organic methods are as efficient, economical and financially competitive as conventional methods, and better for the soil and the environment, according to a report documenting 15 years of findings from The Rodale Institute’s long-term Farming Systems Trial™. The experiment covers 12 acres and compares highly productive, intensive corn/soybean systems under conventional and organic management. The experiment demonstrates that after a transitional period of about four years, crops grown under organic systems yield as well as, and sometimes better than, those grown conventionally. In years of drought, organic systems can actually out-produce conventional systems. Specific findings:
  1. "Organically managed soils achieve better physical structure. Soils in the organic systems gradually became looser and more porous, and absorbed and held water better than conventionally managed soils.
  2. The organic soils "had reduced levels of nitrate leaching compared to the conventional soils and were more effective as a carbon sink."
  3. "Water is able to percolate into the organically managed soils at a faster rate. During rain storms, more water will be absorbed into the soil and less will run over the surface and out of the field."
  4. "As measured by soil respiration rates and available or potentially available nitrogen levels, both of the organic systems indicate higher levels of microbial activity than the conventional system. Potentially more significant, the organic and conventional systems have differences in the species composition of microorganisms."
  5. "Both organic systems showed significant ability to absorb and retain carbon, raising the possibility that agricultural practices might play a role in reducing the impact of global warming."

Source: The Rodale Institute Farming Systems Trial™: The First 15 Years, by Cass Petersen, Laurie E. Drinkwater, and Peggy Wagoner, the Rodale Institute, 1999.

  • A 1987 study that compared adjoining organic and chemically treated wheat fields in Washington State found that the organic fields had eight more inches of topsoil than their chemical neighbors and only one-third the erosion loss.
    Source: Donella H. Meadows, "Our food, our future," in Organic Gardening, September/October 2000.

  • One teaspoon of compost-rich organic soil hosts 600 million to 1 billion helpful bacteria from 15,000 species. One teaspoon of chemically treated soil can host as few as 100 bacteria. Source: Elaine R. Ingham, soil scientist, Oregon State University, in "Our food, our future," by Donella H. Meadows, in Organic Gardening, September/October 2000.

  • It takes approximately 3,000 years for nature to produce 6 inches of topsoil. Every 28 years, 1 inch of topsoil is lost as a result of current farming practices. Organic biointensive farming can produce 6 inches of topsoil in as little as 50 years—60 times faster than the rate in nature. Source: Maine Organic Farmer & Gardener, 1999, in "Our food, our future," by Donella H. Meadows, in Organic Gardening, September/October 2000.

  • The way manure is stored makes a big difference in terms of the effects it has on the soil. Studies have shown, for instance, that composted manure makes it decompose more slowly, thus releasing nitrogen more slowly in the soil. Thus, it becomes more of a soil builder. About 25 percent of the dry matter from composted cow manure is in the form of ligno-proteins, a marriage of lignins and proteins. As a result, it is very stable, and decomposes slowly.
    Source: Walter Goldstein, research director at the Michael Fields Agriculture Institute, in a talk, "Healthy Soils, healthy Roots: Part 2," given at Upper Midwest Organic Farming Conference, March 2000, LaCrosse, WI, as published in the November-December 2001 issue of The Organic Broadcaster.

Organic Trade Association, July 2002.

The Organic Trade Association is the leading business association representing the organic industry in the United States, Canada, and Mexico. Its more than 1200 members include growers, processors, shippers, retailers, certification organizations and others involved in the business of producing and selling certified organic products.

© 2001, Organic Trade Association.

2014 Annual Fund

Research and Promotion 2012