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The Heart of Soil: The Importance of Soil Health Principles

Healthy soil is the foundation of productive, sustainable agriculture.

By KoKomal Kamdar, CAPAL Public Affairs Internmal Kamdar, NRCS Public Affairs CAPAL Intern

Madison, Wis. – September 9, 2020 - The U.S. Department of Agriculture (USDA) Natural Resources Conservation Service (NRCS) provides America’s farmers, ranchers and forest landowners with financial and technical assistance to voluntarily put conservation on the ground, not only helping the environment but agricultural operations, too. In cooperation with producers, NRCS is a leader in improving the health of our nation’s soil, taking a leadership role for conducting soil surveys on private lands across the country. A growing number of America’s farmers are using soil health management systems to improve the health and function of their soil, and NRCS is working hand-in-hand with these producers through assistance programs and services.

NRCS helps America’s farmers, ranchers and forest landowners conserve the nation’s soil, water and natural resources. Soil is a living, dynamic resource that supports plant and animal life. It is made up of air, water, different size mineral particles (sand, slit and clay), organic matter and numerous species of living organisms. Soil has biological, chemical and physical properties that are always changing. Soil health, also referred to as soil quality, is defined as how well soil does what we want it to do. Healthy soil gives us clean air and water, bountiful crops and forests, productive grazing lands, diverse wildlife and beautiful landscapes.

Healthy soil.The soil health foundation consists of four principles, which are: (1) maximize soil cover, (2) minimize disturbance, (3) maximize plant diversity and (4) maximize continual living roots.

Maximizing soil cover, provides numerous benefits for cropland, rangeland, hayland, gardens, orchards, road ditches and more. Maximizing soil cover can be accomplished by incorporating cover crops into the system or maintaining crop residues from the previous crop year. Continuous soil cover protects soil from wind and water as it moves across the soil surface, holding the soil in place along with valuable organic matter and nutrients. Soil cover also reduces soil evaporation rates, keeping more moisture available for plant use. Soil cover helps maintain a more moderate range of soil temperatures, keeping soil warmer in cold weather, and cooler in hot weather. Like humans, the soil food web functions best when soil temperatures are moderate. Additional soil cover benefits include reduced compaction, weed growth suppression and habitat. Rainfall on bare soils is one cause of soil compaction; however, when rainfall hits the live or dead plant material on the soil surface instead of bare soil, much of the raindrop energy is dissipated. Soil cover also limits the amount of sunlight available to weed seedlings. Furthermore, it provides a protective habitat for the soil food web’s surface dwellers. When we supply the soil surface with a diversity of residues from one year to the next, such as a multi-species cover crop, we can achieve the benefits of soil armor and still maintain a fully functioning nutrient cycle.

Minimizing disturbance is essential for building soil health. Soil disturbance can generally occur in three different forms: (1) biological disturbance, such as overgrazing, (2) chemical disturbance, such as overapplication of nutrient and pesticide and (3) physical disturbance, such as tillage. Over time, tillage implements reduce and remove the pore spaces from our soils, restricting infiltration and destroying biological glues which hold our soils together. Ultimately, tillage results in one or more of the following: water erosion, wind erosion, ponding water, crusting and soil organic matter depletion. Fortunately, it is possible to reverse the impacts from tillage and improve soil function. Minimizing soil disturbance is a good start to rebuilding soil aggregates, pore spaces, soil glue substances and soil organic matter. This is an essential step for long term soil productivity.

Maximizing biodiversity is essential for building soil health. Supplying soil with the benefits of plant diversity is essential. The northern plains landscape has historically been described as having abundant plant diversity, where numerous species work together as a community to provide forage for large herbivore populations. Our soils were built over geological time in this environment. Settlement of the plains brought agriculture, which replaced the existing polyculture perennial landscape into a monoculture annual landscape. We can begin to mimic the original plant community by using crop rotations which include all four crop types: warm season grass, warm season broadleaf, cool season grass and cool season broadleaf. Diverse crop rotations provide more biodiversity, benefiting the soil food web; which in turn improves rainfall infiltration and nutrient cycling, while reducing disease and pests. Crop rotations can also be designed to include crops which are; high water users, low water users, tap root, fibrous root, high carbon crops, low carbon crops, legumes and non-legumes, to name a few. Diverse crop rotations mimic our original plant diversity landscapes. They are important to the long-term sustainability of our soil resource and food security.

Radish in Corn StubbleThe final important principle for developing soil health is maximizing the presence of living roots, allowing for a continual live plant feeding carbon exudates to the soil food web during the entire growing season. Our cropland systems typically grow cool or warm season annual cash crops, which have a dormant period before planting and/or after harvest. Cover crops are able to fill in the dormant period and provide the missing live root exudate, which is the primary food source for the soil food web. Cover crops may be incorporated into a cropping system as annuals, biennials, or perennials. Cover crops can address a number of resource concerns, including harvesting CO2 and sunlight, providing carbon exudates to the soil food web and building soil aggregates and pore spaces, which improves soil infiltration. They also cover the soil, controlling wind and water erosion, soil temperature, and rainfall compaction; help catch and release inorganic nutrients improving water quality; and provide pollinator food and habitat, weed suppression, wildlife food, habitat and space. Cover crops can also help in livestock integration, adding crop diversity, trying and adjusting cover crop combinations can also tweak carbon/nitrogen ratios, to either accelerate or slow decomposition.

Soil health benefits include energy savings by using less fuel for tillage and maximizing nutrient cycling; water savings by increases in drought tolerance infiltration and water holding capacity as soil organic matter increases; disease and pest reduction; and sustainability and plant health improvements. 

Whether you grow corn or raise beef cattle, or something in between, NRCS is here to help you build the health of your soils and strengthen your operation. For more information about how you can establish an effective soil health system on your unique operation, contact your local NRCS Service Center by visiting www.farmers.gov.

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