Soil Health Principles
What is Soil Health?
Soil health is “the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans.” (USDA, NRCS) Achieving soil health requires a systems approach that includes five principles: Limited Disturbance, Soil Cover/Armor, Living Roots, Diversity, and Integrating Livestock.
Limit physical, biological, and chemical disturbance of soil. Soil structure includes aggregates and pore spaces. Any form of soil disturbance reduces the soil’s ability to function.
Physical Disturbance: The most significant form of physical disturbance is tillage. Tillage decreases the amount of pore spaces in soil and destroys the glues (aggregates) that hold soils together. Tillage results in water erosion, wind erosion, ponding water, surface crusting, and soil organic matter depletion. Cattle trails and loafing areas or prolonged grazing are also impacts of physical disturbance.
Biological Disturbance: Plants harvest sunlight and carbon dioxide to produce sugars that feed the soil biome through root exudates. Overgrazing is the primary method of biological disturbance. Taking too much of the plants limits both the amount of soil armor above ground and the amount of biomass below ground. Other forms of biological disturbance include introduction of invasive species from bare areas, use of monocultures, and fallow. Each of these cause biological imbalances that can affect soil functions.
Chemical Disturbance: Over applying fertilizers, herbicides, pesticides, and fungicides can harm the life within the soil negatively affecting soil structure.
Keep the soil covered as much as possible.
Keeping soil covered:
- Controls wind and water erosion by dissipating energy from raindrops and wind.
- Prevents moisture evaporation by shading the soil surface.
- Suppresses weed growth by limiting sunlight available to weed seedlings.
- Moderates soil temperature by acting like shade in hot weather and a blanket in cold weather.
- Increases soil life by providing food and habitat for macro- and microorganisms.
Maintain a living root throughout the year. Soils are most productive when soil microbes have access to living plant material. Living roots can be from a commodity crop, cover crop, or forage crop.
- Provide carbon and organic acid substances to the soil food web by harvesting sunlight and carbon dioxide.
- Build soil aggregates and pore spaces to improve soil infiltration.
- Provide soil cover/armor.
- Create opportunity to integrate livestock.
- Add crop diversity.
- Form symbiotic relationships with mycorrhizal fungi and bacteria to acquire nutrients and increase aggregate stability.
Strive for diversity of both plant and animal species. Diversity enhances ecosystem function and increases soil and animal health. Diverse plants on the surface promote diverse soil biology. To maximize the carbon going into the soil, it is important to have a diverse mix of plant types – warm season grasses, cool season grasses, warm season broadleaves, cool season broadleaves, high carbon, low carbon, legumes, non-legumes, high water users, and low water users.
- Increases rainfall infiltration
- Increases nutrient cycling
- Increases biodiversity – above and below the surface
- Reduces plant diseases
- Reduces pest pressure
Ways to incorporate more diversity:
- Longer crop rotations
- Cover crops
- Relay cropping
- Perennial species planting
- Biological amendments
Nature does not function without animals. Proper grazing management improves soil health. Well-managed grazing recycles nutrients through improved manure distribution, reduces plant selectivity, and increases plant diversity. The most important factors in grazing systems are allowing adequate rest for the plants to recover before grazing again and avoiding overgrazing the plants. Overgrazing reduces soil armor and leads to decreased root biomass and less carbon storage.
Ways to incorporate livestock:
- Winter and fall grazing cover crops and annual crop residues.
- Summer grazing a full season cover crop.
- Second grazing of a full season cover crop during the fall or winter.
- Winter feeding on hayland fields by rolling out bales or bale grazing.
- Include perennials for grazing as part of crop rotation.
- Removing fallow and replacing it with a high biomass cover crop that will be grazed during that period.