Fine Tuning Your Grazing System: Addressing the Weakest Link

by Heather Darby – UVM Extension, and Sarah Flack

Are you capturing all the sunlight that lands on your farm?  Is sunlight being converted into pasture plants efficiently?  Are soils fertile and biologically active so that plant health and solar conversion is maximized?  Is the water cycling through the farm in the best possible way so that it is available to the plants when they need it?  Is the livestock grazing system improving your farms ability to covert sunlight into high quality forages?  Are livestock harvesting forages efficiently and converting it into meat, milk & fiber.  These are some questions to ask to determine if the processes that drive our grazing systems are functioning properly.

Our grazing systems function through four fundamental processes: water cycle, mineral cycle, community dynamics, and energy flow. Becoming acquainted with these processes will enable you to monitor your grazing system and identify and fix your farm’s weak links.  Managing your grazing systems in terms of these four processes will enable you to more efficiently convert sunlight into high quality forages and produce more meat and milk.

An Effective Water Cycle:  Water is constantly being cycled between the atmosphere, ocean, and  land. As the water evaporates, vapors rise and condense into clouds. The clouds move over the land, and precipitation falls in the form of rain, ice, or snow. Some water runs off into streams, rivers, lakes, or oceans. Some of the water penetrates the soil surface and becomes bound to soil particles or flows down to replenish groundwater supplies. The majority of the water that is retained in the soil will be drawn up plant roots and eventually transpired into the atmosphere.  The function of water in soil is critical to plant and animal life therefore creating an effective water cycle will encourage productivity both above and belowground.  An effective water cycle is that which infiltrates into the soil and becomes available for plants and soil organisms.  An ineffective water cycle is that which has water loss from the soil surface in the form of runoff or evaporation and the plants get minimal opportunity to utilize the water.  An effective water cycle helps buffer the erratic nature of rainfall making floods and droughts less severe. While an ineffective water cycle increases the frequency and severity of drought and flood events.  Monitoring the effectiveness of your water cycle is easy. While walking your land look for the following key identifiers:

An Effective Mineral Cycle:  Similar to the water cycle, minerals flow in a cyclical pattern. Living organisms continually release nutrients from their bodies, in the form of wastes, which are by-products or leftovers from metabolism. One organism’s wastes become another organism’s nutrients. This process is called mineral cycling. Every plant and animal alive on earth is made of nutrients that have been used and re-used by life over and over again. In the context of a grazing system, this means that an effective mineral cycle will continually cycle and provide the essential nutrients needed by plants, soil microorganisms and animals. In order for a mineral cycle to be at its optimal the soil must be biologically active (microorganisms, and roots) with ample aeration and water (effective water cycle).  Plants are responsible for lifting nutrients from the soil to the surface and making them available to animals.  Plants use their roots to extract minerals from the soil. A good mineral cycle will include plants that have healthy large root systems as well as root systems with varying structure.  Plant and animal material containing nutrients from the soil are eventually returned to the surface in the form of dead plant and animal residue (i.e. organic matter).  At this point the minerals in these plants are not available for reuse by plants. This material is broken into smaller pieces by surface-feeding insects and other soil organisms.  The minerals will be incorporated into microbial biomass and their byproducts (various nutrients) will become available to plants. Nutrients contained the microbial population will be released for plant uptake as they die and our decomposed by other soil organisms. To keep the soil biologically active the living organisms must also have ample moisture and air. This is only possible by maintaining the condition of the soil surface so that soil can retain moisture and air.  Some key identifiers to an effective mineral cycle are listed below:

Effective Energy Flow:  In general, good energy flow begins with sunlight landing on leaves, where it is converted into forage, and the forage is then converted by grazing or harvest.  How well energy flows through a farm depends on how sunlight fuels the biological systems on the farm.  Sunlight lands on a green plant, allowing it to grow.  The plant is eaten by an animal which is then eaten by a predator and so on.  Eventually the plants and animals die and are consumed by decomposing organisms.  In this process, energy is taken underground by roots as well as by the decay process.  An effective energy flow on a farm depends on having plenty of total area of actively growing leaves which can actively convert sunlight into more plant growth as efficiently as possible, and for as long a growing season as possible.  Energy flow is also dependent on how forages are grazed, harvested and decomposed.  Monitoring energy flow on the farm involves finding where solar energy whichcould be captured to create more life is not being used.  Some key identifiers to an effective energy flow are listed below:

Effective Community Dynamics:  Community dynamics are improved on a farm as the level of diversity and complexity increases.  As the complexity of the community of plants and animals increases, the lands stability, health, productivity and resilience will also increase.  Understanding this can be aided by thinking of the plant community in terms of succession – the stages or steps of plant community development.  Generally, bare ground is first replaced by moss, algae or lichen, then this converts to annual herb or grass species, then more perennial grasses, then to brushy species and then gradually to forest.  This is a gradual process with involves an increasingly diversity of species and increasing amounts of biomass.  When monitoring community dynamics, some things to look for include: