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The ABCs of Soil Health

by Pennsylvania NRCS

Healthy soil is the foundation of productive, sustainable agriculture. Understanding how soils function is the foundation for good stewardship. To this end, NRCS has developed the ABCs of Soil Health.

NRCS staff teach about soils at a No-Till Alliance event. Photo credit: York County Conservation District

Managing for soil health allows producers to work with the land – not against – to reduce erosion, maximize water infiltration, improve nutrient cycling, save money on inputs, and ultimately improve the resiliency of their working land.

NRCS is here to help you build the health of your soils and strengthen your operation. A key component in managing soil health is Assessment.

A soil health assessment is the first step in understanding the chemical, physical and biological functioning of soil and can be done in the field and in the laboratory. All soils are not created equal – different indicators can show how well a soil is functioning related to inherent characteristics and dynamic management practices.

A soil health assessment evaluates the chemical, physical and biological functioning of the soil and is the necessary first step to determine its current condition and level of function. Healthy soils carry out various critical functions that contribute to crop production, environmental quality, and resilience.

An in-field or lab assessment provides a snapshot of the current soil function and an indication of how management may affect function in the future. Soil health cannot be determined by simply monitoring crop yield. Although declining yields may be an indication of poor soil health, yield can often be maintained for some time even as soil health is declining by increasing fertilizer levels and other inputs, especially during years with optimal growing conditions.

Group learning how to use a penetrometer as part of an in-field soil health assessment. Photo Credit: Reginald Jackson, USDA NRCS.

During the assessment, various dynamic or management-influenced soil properties are evaluated as indicators to determine how well the soil is functioning relative to its inherent capacity. Soil health indicators generally assess the soil organic matter dynamics, structural stability, microbial activity, and carbon and nitrogen food sources.

All soils are not created equal; for example, sandy soils will respond to management differently than clayey soils. Each assessment should consider inherent limitations and characteristics of the soil and the environment. Results of the assessment provide the producer with a starting point on a roadmap to improve soil health.

Another key to managing soil health is Biodiversity.

Biodiversity is the variety of life in an ecosystem and important to healthy soils because of the roles different crops and soil organisms play in soil functions. The healthiest of soils are those with abundant diversity!

Above and below-ground diversity is important to the functioning of healthy soils. Maintaining biodiversity in agricultural systems requires protecting habitats and utilizing management practices that reduce impacts on the soil biology, wildlife, pollinators, and beneficial insects.

The most effective ways to increase biodiversity in agricultural fields are by managing diverse crop and livestock species, reducing tillage, avoiding disruptive fertilizer and pesticide applications, providing cover, and implementing integrated pest management. In annual cropping systems, new plant species can be added by diversifying crop rotations and integrating mixes of cover crops.

Close-up image of diverse plantings including grass, broadleaf, and legume species. Photo Credit: Keela Deaton, USDA NRCS

Diversity can also be accomplished by integrating livestock, planting diverse perennial forages, managing grazing, and agroforestry. Management of adjacent, less productive field margins on farms is another way to enhance biodiversity for wildlife, pollinators, and other beneficial insects. Soil health management, along with other agricultural innovations, can protect biodiversity on managed and unmanaged lands.

The healthiest soils are those with abundant diversity!

Carbon is the building block of all life on earth and an important part of photosynthesis and respiration. Carbon dioxide (CO2) is a greenhouse gas that contributes to climate change. Plants remove CO2 from the air and convert it into sugar, creating food for plants to grow. From that initial CO2 and sugar, plants synthesize numerous other carbon-based compounds for their growth and development.

When plants die, the residue decomposes and some of the carbon is incorporated into soil as organic matter. Energy-rich carbon compounds are also released from the roots of living plants, providing a nutrient-rich environment around root systems for microorganisms to flourish. These root compounds are also used by soil organisms to increase aggregate stability, binding soil particles together.

The dark color of this soil is mostly the result of organic forms of carbon created by soil organisms living in association with the exudates of living plant roots. Photo Credit: Marlon Winger, USDA-NRCS

Roots grow down into the soil profile where carbon is stored longer than in the plant residues deposited on the surface. By reducing tillage, diversifying rotations, cover cropping in annual systems and increasing perennial cover on marginally productive land or for other land uses, CO2 is removed from the air by plants and stored in the soil as organic matter. These and other practices like biochar or compost amendments have the potential to sequester carbon in soil and thereby help mitigate climate change.


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