Soil health, also referred to as soil quality, is defined as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans. It is important to manage soils so they are sustainable for future generations. To do this, we need to remember that soil contains living organisms that when provided the basic necessities of life - food, shelter, and water - perform functions required to produce food and fiber.
Only "living" things can have health, so viewing soil as a living ecosystem reflects a fundamental shift in the way we care for our nation's soils. Soil is teaming with billions of bacteria, fungi, and other microbes that are the foundation of an elegant symbiotic ecosystem. Soil is an ecosystem that can be managed to provide nutrients for plant growth, absorb and hold rainwater for use during dryer periods, filter and buffer potential pollutants from leaving our fields, serve as a firm foundation for agricultural activities, and provide habitat for soil microbes to flourish and diversify to keep the ecosystem running smoothly.
(Source: https://www.nrcs.usda.gov/wps/portal/nrcs/main/soils/health/ )
Soil Health Improvement
Managing soil for improved health demands a long-term commitment to using combinations of soil-enhancing practices. The strategies listed below can aid you in inhibiting pests, stimulating natural enemies and — by alleviating plant stress — fortifying crops’ abilities to resist or compete with pests.
Add Organic Materials
Add plentiful amounts of organic materials from cover crops and other crop residues as well as from off-field sources like animal manures and composts. Because different organic materials have different effects on a soil’s biological, physical and chemical properties, be sure to use a variety of sources. For example, well-decomposed compost may suppress crop diseases, but it does not enhance soil aggregation in the short run. Dairy cow manure, on the other hand, rapidly stimulates soil aggregation.
Keep Soils Covered
Keep soils covered with living vegetation and/or crop residue. Residue protects soils from moisture and temperature extremes. For example, residue allows earthworms to adjust gradually to decreasing temperatures, reducing their mortality. By enhancing rainfall infiltration, residue also provides more water for crops.
Reduce Tillage Intensity
Excessive tillage destroys the food sources and microniches on which beneficial soil organisms depend. When you reduce your tillage and leave more residues on the soil surface, you create a more stable environment, slow the turnover of nutrients and encourage more diverse communities of decomposers.
Adopt other practices that reduce erosion, such as strip cropping along contours. Erosion damages soil health by removing topsoil that is rich in organic matter.
Alleviate the severity of compaction. Staying off soils that are too wet, distributing loads more uniformly and using controlled traffic lanes — including raised beds — all help reduce compaction.
Use best management practices to supply nutrients to plants without polluting water. Make routine use of soil and plant tissue tests to determine the need for nutrient applications. Avoid applying large doses of available nutrients — especially nitrogen — before planting. To the greatest extent possible, rely on soil organic matter and organic amendments to supply nitrogen. If you must use synthetic nitrogen fertilizer, add it in smaller quantities several times during the season. Once soil tests are in the optimal range, try to balance the amount of nutrients supplied with the amount used by the crops.
Forage-livestock Systems Impact
Put animal and grazing impact to work for you. Livestock provides nutrient cycling in pastures, contributing to soil organic matter, and the grazing action on forage plants encourages root growth and root exudation of plant sugars that feed soil microorganisms.
For livestock producers, this boils down to a combination of perennial pasture, cover crops in rotation, and good grazing management. Perennial pastures, because of the lack of soil disturbance and permanent cover, are higher in carbon and organic matter than tilled crop fields. This biological system has a stable habitat to conduct business, and the nutrient cycles can sustain themselves. However, by adding livestock, we get a multiplier effect on soil health, even in systems that are cropped with a cash crop as part of the rotation.
Grazing is known to increase soil carbon and nitrogen in the soil. As an animal grazes, it sends a signal to the plant to pump out sugars through its roots into the surrounding soil. These root exudates, sugars developed by the plant through photosynthesis, are food sources for the microorganisms in the soil. The action of grazing jump-starts the soil food web and increases nutrient cycling, making nutrients available to plants.
Cover crops are known to benefit the soil by feeding soil life, buffering temperatures, and increasing water efficiency. Many crop farmers are familiar with cover crops, but with livestock and cover crops in combination, you have all the tools you need to build soil health. Grazing is often the missing link for crop farmers. By putting animals on cover crops you can close the loop and develop a more resilient system.
Think of livestock as biological “roller-crimpers,” or cover crop terminators. Combining the below-ground effects of grazing on root exudates with the biological contribution from animals far exceeds the benefits of cover crops alone. Because the microbes in the rumen are similar to the microbes in the soil, ruminant animals prime the soil with biological life, contributing to the health of the soil.
If you’re a farmer who has a predominately cash-crop-oriented income, it may be attractive to graze cover crops in rotation with cash crops. Annual crops can be rotated to perennial pasture every few years. You can also incorporate grazing of cover crops in a strictly cash crop system, as Gabe Brown has demonstrated. His fall biennial crop > warm season cover crop > fall biennial crop > cash crop rotation works well in his system. In this system, you only have one year off from cash crop, but you get three cover crops incorporated, all grazed. This cover crop sequence works very well to “prime” depleted soils.
It seems like there is a lot involved in managing pasture fertility holistically… and there is. The biological processes are complex and they interrelate with weather, moisture, season, crop selection, and livestock. Even soil scientists do not understand everything that goes on in the soil, but we do have a pretty good idea of the processes, and we know that biology is the basis for soil function. We also know that energy drives the whole system.
Transitioning to a biological system from a chemical system is a slow process, and it’s important to recognize that it will take several years for soils to turn around. Be patient, and as Ray Archuleta, a soils conservationist with NRCS, says, “Have the integrity to believe that nature will work with you over time, that it’s going to work.” This is important, because there are going to be some problems that crop up. It could be anything from decreased weaning weights on calves, to weed problems, to livestock parasites. Expect these problems to occur, because you’re dealing with a biological system that is trying to get back into balance. Don’t jump ship at the first obstacle and succumb to the temptation to revert to an input-based system. Resilience and the integrity to stay focused will pay off in the years to come as the biology builds to the point of sustainability.
So, how do you get started? Remember the three practices we spoke of earlier: perennial pasture, cover crops, and grazing management. These practices build soil carbon, which is the key to fostering soil health and plant fertility. Making the transition takes time and attention, but the benefits are long term. Think of it as an investment in your soil, just like you invest in livestock and equipment. And as you begin this journey of renewal, remember that it’s a biological system that is fully dependent on the almost incomprehensible diversity of life and life processes that happen unseen, among the roots just under the soil surface.
It took decades for your soil to degenerate, so expect several years for your farm to recover. Don’t make the mistake of expecting to reverse the tide in one year. As you transition, keep in mind the following concepts: when you feed soil microbes, you feed the plant—productivity is based on the relationships between plants, soil, and animals. The process of nutrient transfer is kept strong by adding organic matter. Reduce your off-farm inputs to reduce cost, and transition slowly. Have integrity that it will work by staying the course even when the system seems to crash. Observe and adapt. And if your soil is low in carbon, don’t expect it to work. To fix it, start by putting in one or two years of cover crops and graze it appropriately to get the system primed. You might be surprised by the results.
Managing for carbon by keeping soils covered with growing plants and with managed defoliation through grazing, builds the organic matter that provides the fertility pastures need to be productive.
Leave areas of the farm untouched as habitat for plant and animal diversity.
Individual soil-improving practices have multiple effects on the agro-ecosystem. When you use cover crops intensively, you supply nitrogen to the following crop, soak up leftover soil nitrates, increase soil organisms and improve crop health. You reduce runoff, erosion, soil compaction and plant-parasitic nematodes. You also suppress weeds, deter diseases and inoculate future crops with beneficial mycorrhizae. Flowering cover crops also harbor beneficial insects.
CAUTION: When designing fields to manage specific pests, other pests can reach damaging levels. For example, spacing crops closely can prompt disease outbreaks.
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