Soil Health in Forage-Livestock Systems
Leo Vieira-Filho, Postdoctoral Fellow
Liliane Silva, Assistant Professor and Forages Specialist
Soil health is defined “as the continued capacity of soil to function as a vital living ecosystem that sustains plants, animals, and humans” (USDA, 2024). Soil health is measured by assessing chemical (e.g., nutrient concentration, pH and organic matter), physical (e.g., bulk density, infiltration and water holding capacity) and biological properties (e.g., microbial biomass, potentially mineralizable nitrogen and soil enzymes) of the soil.
There are several ways to increase soil health in forage systems. Incorporation of legumes in the forage system, for example, is an excellent way to increase forage diversity and boost microbial activity. Consequently, nitrogen from the atmosphere will be fixed in the soil by legumes, resulting in lower expenses with inorganic fertilizer. Adopting an alternative source of nutrients, such as poultry litter, will also help promote soil health. Poultry litter is a source of many nutrients, including nitrogen, phosphorus, potassium, magnesium and sulfur. Those practices have the potential to increase organic matter in the soil, which will favor nutrient-holding capacity and water-holding capacity.
An additional approach to promote soil health and also cope with soil compaction is the incorporation of plants with a “more aggressive” root system. An example of a forage with an aggressive root system is radish. After the growing season, the root system will start getting decomposed and will leave “empty spaces” in the soil, which will favor root aeration and water flow. Consequently, subsequent forages will be more successful in establishing their roots and scavenging nutrients. The use of a penetrometer to detect soil compaction is an advisable practice. This way, it will be possible to know for sure if the issue in the area is, in fact, related to soil compaction.
However, none of the above-recommended practices will significantly improve soil health without proper grazing management. Overgrazing pastures will lead to the death of stands, which will in turn reduce microbial activity and organic matter accumulation. Typically, forages being overgrazed will produce a lower root biomass, which will make more difficult for plants to thrive during drought events, for example. In addition, a lower root biomass will result in lower carbon and nitrogen fixation. Proper grazing will, on the other hand, favor microbial activity, organic matter accumulation and nitrogen accumulation.
References:
USDA, 2024. What is soil health? https://www.nrcs.usda.gov/conservation-basics/natural-resource-concerns/soils/soil-health
