“Soil Health” as Defined by USDA NRCS
Prepared by Calvin F. Bey
Soil health, and how it can be improved, is or should be of huge importance to gardeners and farmers today. It is important because the health of many soils have been compromised by applying chemicals, plus we still have serious soil erosion problems in the United States and throughout the world.
USDA takes this soil health problem seriously. USDA NRCS (Natural Resource Conservation Service, i.e. the old Soil Conservation Service) has defined what “healthy soil” means, and what steps it takes to develop the same. These simple steps are appropriate advice for small organic gardeners, and for farmers with large acreages.
From the NRCS publication soil health is defined as “the capacity of the soil to function.” The functions of the soil include; water infiltration, recycling nutrients, and providing water and nutrients to feed the plants. In what follows, everything from the NCRS publication is in quotes and is highlighted.
So how do we improve soil health? According to NRCS, “managing for soil health can be improved by disturbing the soil as little as possible, growing many different species of plants in the soil as often as possible, keeping living plants in the soil as often as possible, and keeping the soil covered all the time.”
These practices are generally used by organic/natural/biological gardeners and farmers. The practices are neither magical or mystical. They are the same natural processes that that gave us the deep rich prairie soils and the forest soils that grow 300 foot redwoods. They are practices that are in harmony with nature, not chemicals and artificial practices that often work against development of healthy soils. They are practices that are urgently needed to heal the earth now.
1. Disturb Soil Less. From NRCS, “Tilling the soil is the equivalent of an earthquake, hurricane, tornado, and forest fire occurring simultaneously to the world of soil. Simply stated, tillage is bad for the soil.”
There are plenty of examples of successful no-till gardens. I have never used a tiller in my garden. Tilling destroys soil structure and decreases soil water holding capacity. It reduces the natural biological life and in the end reduces productivity.
2. Grow Diverse Crops. Growing many different species of plants, over time and space, increases the number and varieties of soil microbial populations and is an insurance program against disease and pest problems. Sugars, made from the diversity of plants, are released from plant roots into the soil. In the soil, the sugars serve as food for soil microbes, which in turn decompose organic matter into nutrients that support plant growth. Its simply the way the natural soil development process works.
3. Grow Living Roots Throughout The Year. NRCS says, “Healthy soil is dependent upon how well the soil food web is fed.” Providing plenty of sugars that exude from live roots means easily accessible food for soil microbes. The thrust is about maintaining a suitable habitat for the myriad of soil food web creatures. These microscopic and macroscopic individuals, working day and night, essentially control soil development. One teaspoon of healthy soil can easily contain more individuals than there are people on earth. Its clear: we need to be gentle and kind to the soil.
4. Keep the Soil Covered. NRCS says, “Soil should always be covered by growing plants and/or their residues, and soil should rarely be visible from above.” Soil cover protects the soil aggregates from beatings by the rain, suppresses weeds, keeps the soil cool and moist, and promotes soil microbial activity.
From personal experience, I know that following these four steps will lead to soils that are fluffy and mellow, easy to work, and productive. The fact that USDA recommends these practices should be a clear signal for all gardeners to switch from the chemical to the natural/healthy approach. The chemical approaches simply are not the way to develop healthy soils. In the end, a healthy soils is really about healthy plants, healthy produce and healthy consumers. That applies to all of us and and all consumers and that’s important.
Another important point for more effective gardening, not included in the NRCS publication, is mineral and nutrient management. This is a hefty topic in itself, and deserves its own time and place.
Reference: USDA Natural Resource Conservation Service. November 2011. Farming in the 21st Century, A practical approach to improve Soil Health. Developed by the Soil Quality National Technology Development Team with contributions from North Dakota NRCS.