Soil Management for Pastures and Rangelands
Grazing Impacts on Soil Properties
Grazing effects physical, chemical, and biological soil properties. Grazing animals in a perennial pasture system have both positive and negative impacts on soil change. Some studies have shown that managed grazing can increase soil organic matter and improve its structure, which can result in improved water infiltration and storage, as well as reduced erosion. Managed grazing can also increase forage production, leading to increased carbon sequestration. However, intensive livestock grazing can lead to the disturbance of biological crusts and other surface features impairing the soil’s physical, biological, and hydrological function. Some soils in a perennial pasture system are very sensitive to management and disturbance and can undergo rapid change. Significant shifts in vegetation generally are associated with changes in soil properties and processes and/or the redistribution of soil resources across the landscape. In some cases, such as accelerated erosion resulting in a change in the soil profile, this shift may be irreversible, while in others, recovery is possible.
Soil Physical Properties
Perennial pasture systems can enhance soil health by reducing erosion, building soil organic matter, sequestering carbon, increasing macro and micropore space, and retaining more plant available water. However, adverse effects can also occur, especially to soil physical properties due to hoof action by livestock. Pugging occurs when the hooves of grazing livestock penetrate the soil surface during wet conditions causing damage to pasture plants as well as soil structure.
Soil Chemical Properties
Unlike cropping systems where large amounts of nutrients are removed from a field in grain or hay, the majority of nutrients are recycled in grazing systems through manure and urine deposition. For most nutrients, over 90 percent of what is ingested ends up being excreted. Through this deposition, overall soil fertility is maintained and reliance on inorganic fertilizer inputs is significantly reduced.
Soil Biological Properties
Managed grazing allows plants to retain enough leaf area to support quick foliage regrowth and continued root growth. In addition, moderately defoliated plants tend to increase root exudates which stimulate soil microbial activity. This increase in microbial activity leads to more rapid decomposition of roots that have died during normal growth which improves nutrient cycling and will eventually lead to an increase in soil organic matter.
Click on the following topics for more information on soil management for pastures and rangelands.
