From an ecological standpoint, a “disturbance” is not inherently bad or good. The same management action can result in negative or positive feedback depending on the timing and intensity. Strategizing disturbance allows landowners to adaptively implement the tools (i.e. grazing management, brush management, etc.) in a way that enhances ecosystem process such as energy flow, community dynamics and functioning nutrient and water cycles. The timing of disturbance is crucial. Timing a disturbance prior to a change of season can reduce existing vegetation and stimulate new vegetation. Vegetation after senescence will have reduced growth, disturbing senesced vegetation with grazing will stimulate new growth. Allowing rest and recovery from disturbance is beneficial. The duration of the period between disturbance/grazing will vary across the U.S. according to factors like season and moisture availability.

If the ground is bare, more water is lost by evaporation than by transpiration, which means it isn’t getting used by the plants for plant growth as temperatures get hotter.  Also, some soil biology can be negatively impacted at hotter temperatures.  A 15 degree or greater difference in temperature is common between systems with good plant cover and residue verses those without.  Residue also aids in increasing infiltration, reducing erosion and physically cushioning the soil from hoof traffic.  

How do we get more residues on pastures? Through trampling, senescing plant leaves, and plant materials falling from herbivore’s mouths. The duff from ungrazed grass serves as plant residue and perennial grasses immobilize nutrients later mineralizing nutrients for additional more uniform plant growth.

There are also negative impacts of too much litter (soil cover). This could cause a reduction in the amount of carbon sequestered, and reduction of organic matter distribution in the profile. It could also cause a reduction in infiltration due to discontinuity between litter and soil surface because of the thatch layer and due to a shallow, thick mat of roots near the surface. You can also see changes in root morphology, severe reduction in mycorrhizal fungi and possibly an imbalance of nitrogen in the system. 

Grasslands are typically best planted in perennial forages with annuals planted for transition periods like renovating an existing stand or when transitioning from crop to grass.  Cool season annuals are often interseeded into warm season pastures in areas with warm enough winter temperatures for these species to grow. crops include rye, triticale, barley, wheat, oats, clovers and other legumes, turnips, and radishes. Warm season cover crops include sorghums, millets, cowpeas and other legumes.  

Annual crops for grazing can include these species as well as crabgrass (warm season) or annual ryegrass (cool season).  Planting several species together in an annual or perennial mixture can increase their impact on soil health. Often different species in a mixture perform better if planted in different seasons. For example, a cool season grass legume mix is best if the grass is established in the fall and legumes are seeded in early spring. Each forage species provides its own set of benefits, so it’s important to choose the right mixture to meet management goals.

A diverse and fully functioning soil food web provides for nutrient, energy, and water cycling that allows a soil to express its full potential. Diversity in our pastureland species is good for livestock (larger windows of palatability) and wildlife, but it also increases biological diversity below ground.  More diversity in plants and microorganisms leads to healthier systems that are more resilient and resistant to drought and pest issues while improving nutrient cycling and overall system health. Legumes and forbs grow better in some areas than others. 

A healthy, well managed perennial grass stand can cover the soil, cool the soil, provide active living roots most of the year, and feed microorganisms.  A healthy soil ecosystem can best be recognized by soil life activities such as large soil aggregates in the surface soil and by depth of the soil aggregation. If there is excessive tall biomass shading the soil, plant diversity often decreases. If cover is reduced, the addition of diversity like legumes and forbs would be beneficial. Biodiversity increases soil aggregation deeper in the soil profile. Desired functional groups of plants can be seeded or increased through natural regeneration by timing strategic disturbance.

Many native plants are dependent on mycorrhizal fungi, or in other words, they are mycorrhizal fungi obligates.  The mycorrhizal fungi extend the reach of the native plant roots tremendously, allowing them to access water and nutrients from a far greater area in the soil.  But to get that service from the mycorrhizal fungi, the roots must supply food which comes from vigorous plant growth. 

Biodiversity is the variation of life forms within a given ecosystem or field. The different life forms include all of the plants, animals and microorganisms. Increasing the diversity of a forage system increases soil health and soil function, reduces input costs, and increases profitability. 

For Soil Health Management Systems, biodiversity includes animals living within the soils along with microbial diversity. Diversity can be increased through a variety of approaches including plant diversity through diverse pasture mixes, proper integration of grazing animals (e.g. livestock) into the system and direct additions with biological amendments.

All four soil health management principles contribute to biodiversity.

Much of the biological activity in soil happens on and near the root surfaces.  Growing and enhancing the living root system increases and improves that activity. Allowing plants to fully recover between grazing events promotes root growth.  Remember, if we can increase photosynthesis with more leaf area, there can be an increase in rhizosphere activity and thus organic matter increases with better nutrient cycling.