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Soil Health

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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.

  • A four-year study by the International Assessment of Agricultural Science and Technology found that organic agriculture is helpful in protecting soils and conserving wildlife.  The study, which represents the work of over 400 scientists and 30 governments and NGOs, grew out of discussions by the World Bank and the United Nations’ Food and Agricultural Association about the need for an international assessment of the role of agricultural knowledge, science, and technology in “reducing hunger and poverty, improving rural livelihoods, and facilitating environmentally, socially, and economically sustainable development.”


  • Research conducted jointly by scientists at the University if Wisconsin-Madison and the agricultural consulting firm AGSTAT published in the March-April 2008 Agronomy Journal found that organic crop rotations had similar yields to their conventional counterparts.  The research compared six cropping systems (three cash grain and three foraged-based crops), which ranged from diverse organic systems to conventional systems.  Results of this multi-year study found that forage crops produced using organic methods yielded as much or more dry matter as their conventional counterparts “with quality sufficient to produce as much milk as…conventional systems.”  The results of the study also revealed that organic corn, soybeans, and winter wheat produced 90% as well as the same crops produced in a conventional manner. 


  • A nine-year study by USDA Agricultural Research Service (ARS) researchers at Beltsville, MD, has shown that organic farming can build up soil organic matter better than conventional no-till farming can.
    Source: Agricultural Research “No Shortcuts in Checking Soil Health,” July 2007. Posted at


  • The Long-Term Agricultural Research (LTAR) initiative funded by the Leopold Center in Iowa has shown greater yield, increased profitability, and steadily improved soil quality in organic over conventional rotations in grain-based cropping systems, according to an article in the Summer 2007 Leopold Letter. The initiative, begun in 1998, is being conducted at the Neely-Kinyon Research Farm near Greenfield, IA. The research tests whether organic systems relying on inputs such as composted manure can promote stable yields, soil quality, and plant protection. Results are then compared with a corn-soybean rotation supported by greater levels of inputs such as fossil-based fuels.
    Source: Leopold Letter, Summer 2007.


  • 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).


  • 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 decomposes more slowly, thus releasing nitrogen more slowly in the soil. Thus, composted manure becomes 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.


  • 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, "Our food, our future," by Donella H. Meadows, in Organic Gardening, September/October 2000.


  • It takes approximately 3,000 years for nature to produce six inches of topsoil. Every 28 years, 1 inch of topsoil is lost as a result of current farming practices. Organic biointensive farming can produce six 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.

  • 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:

    "Fertilization in organic systems has a positive effect on the content of organic matter and helps to avoid soil acidification;"
    "Organic soil management improves soil structure by increasing soil activity, thus reducing the risk of erosion;"

    "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);"

    "Organic crops profit from root symbioses and are better able to exploit the soil;"

    "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:

    "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.

    The organic soils "had reduced levels of nitrate leaching compared to the conventional soils and were more effective as a carbon sink."

    "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."

    "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."

    "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 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).