Principles for High Functioning Soils 2

PRINCIPLES FOR HIGH FUNCTIONINGSOILS SOIL HEALTH DEFINED Soil health is the continued capacity of a soil to function as a vital, living ecosystem that sustains plants, animals, and humans. Only living things can have “health,” so viewing soil as a living, breathing ecosystem reflects a shift in the way we view and manage our nation’s soils. Soil isn’t an inert growing medium, but rather is the home of billions of bacteria, fungi, and other organisms that together create an intricate symbiotic ecosystem. This ecosystem can be managed to support plants and animals, by cycling nutrients, absorbing, draining and retaining rainwater and snowmelt for use during dry periods, filtering and buffering water to remove potential pollutants, and providing habitat for the soil biological population to flourish and diversify to keep the ecosystem functioning well. KEY SOIL HEALTH PROTECTING THE SOIL HABITAT MANAGEMENT PRINCIPLES The first two principles, shown on the right side of the diagram above focus on protection of the soil These principles are represented in the circular habitat: minimize disturbance and maximize soil diagram to the right to emphasize their relationship as a continuum where each complements the others cover. Practices that use these principles maintain or and also depends on the others. increase stable soil aggregates and soil organic matter (SOM), and protect the surface of the soil that 1. Minimize disturbance is most susceptible to the degrading forces of wind 2. Maximize soil cover and water. Maximizing soil cover also buffers against temperature fluctuations that stress plants and soil 3. Maximize biodiversity organisms, reduces evaporation rates, and increases 4. Maximize presence of living roots the amount of water entering the soil profile from precipitation and irrigation. United States Department of USDA is an equal opportunity provider, employer, and lender. Agriculture PRINCIPLES FOR HIGH FUNCTIONING SOILS 2 SOM is highest at the soil surface and is critical for stabilizing soil aggregates. Maintaining SOM helps support additional soil functions including water infiltration, drainage and storage, nutrient-holding SOIL DISTURBANCES capacity and release, and habitat for soil Physical disturbances such as biota. tillage or compaction from heavy machinery; Chemical disturbances such as fertilizer Worm being born within the pore space of a well- FEEDING THE SOIL and pesticide applications, aggregated soil. especially over application or ORGANISMS misuse. Biological disturbances, such as over-grazing animals that INHABITING SOIL HEALTHY, FUNCTIONING can lead to compaction and reduction in perennial root The second two principles, shown on the left SOILS ARE ABLE TO: systems, introduction of invasive side of the circular diagram, focus on feeding species and/or use of soil organisms. Maximizing the diversity of • Cycle nutrients effectively monocultures can cause biological imbalances which all food (energy and carbon inputs) and • Store carbon and nutrients in soil can affect soil functions. aboveground biodiversity increases the organic matter diversity of soil animals and microorganisms. • Provide good aeration to promote SOIL COVER Diversity not only refers to food sources, but root growth consists of two main forms: 1) also aboveground diversification of plants living plant canopy such as a and animals, and microbial diversification • Improve farm and ranch resiliency growing crop, cover crop, or and profitability grassland; and 2) mulch, either as underground. Diversification stimulates a dead plant material (e.g. crop host of additional benefits including • Improve yield stability residues, prunings from trees breaking disease cycles, providing habitat for • Reduce runoff and erosion and shrubs, thatch in grasslands) or as an amendment (e.g. pollinators, and stimulating plant growth. • Improve water storage and plant compost, bark chips). available water while protecting Maximizing the presence of living roots in water quality BIODIVERSITY is the variation of life forms the soil can be accomplished through • Be resilient to drought, heavy within a given ecosystem or field. eliminating fallow, diverse crop rotation, rainfall events, and temperature The different life forms include all inclusion of cover crops, and/or through extremes of the plants, animals and microorganisms, and their dedicated grasslands (native or pasture). • Reduce disease and pest problems secretions. For soil health Mixing up which plants are grown during management systems, biodiversity can be increased the year or over the course of multiple years Soil Health Management Systems may help to break disease/pest cycles. through a variety of approaches Principles can be generally used in including: plant diversity through When these two principles are properly all production systems to achieve the use of diversified crop this. However, the specific practices rotations, cover crop mixes, applied as part of a soil health management diversity through the proper system, soils can maintain or even increase chosen to implement the principles integration of grazing animals SOM content as well as enhance nutrient must be adapted to each (e.g. livestock) into the system cycling. production system, climate, and includes animals living ecosystem, and soil to effectively within the soils or microbial build and maintain healthy, diversity, as well as direct additions with biological functioning soil. amendments. All four soil health management principles contribute to biodiversity. www.nrcs.usda.gov February 2018 Natural Resources Conservation Service.

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