Grassland Ecosystem Management Using Ecology-Based Farming Methods - an article by Agroregeneration

Grassland Management Using Ecology-Based Methods

Written By: Ryan Mayes and Agroregeneration

2005 photo by Edwin Olson - http://en.wikipedia.org/wiki/File:Konza1.jpg

Pastoral agriculture and soil building involves the use of prairie, grassland, meadow, or savannah based systems to restore soil health and increase ecological diversity.  The use of primary herbivorous grazers such as buffalo, cattle, sheep, goats, and horses is the guiding force behind this method.

Encouragement of perennial grasses and forbs as apex plant species is facilitated by the use of rotational grazing, fire, and broadcast seeding if necessary.  Perennial grasses provide the bulk of carbon input into the soil.  Fertility is increased by the use of leguminous plants such as cowpeas, clover, and alfalfa, as well as mineral mining plants like dandelion, plantain, and dock. 

Irrigation, water collection, and water storage is accomplished through the use of rain catchment systems such as swales, berms, and earthen dams.  Soil infiltration, water retention, texture, and stratification is improved through the use of chisel plows, living mulch, invertebrates, root pathways, and burrowing animals such as prairie dogs and rabbits.

Birds Play an Important Role in Insect Control and Species Composition

Birds are often a missing or underdeveloped livestock component of pastoral based agriculture these days.  However, they do play a fundamental part in the overall health of the ecosystem.  There are many niches which birds fill.  Without them, the cost of herbicides, pesticides, antibiotics, and other biological control agents can cripple a business owner and destroy their land.  Reseeding also becomes extremely expensive and time consuming.

            Known Benefits of Birds

·        Birds will light upon the herbivores and go over their bodies looking for parasites.  This is especially important in the population of control of pests and immediate health of the animals. 

·        The action of the grazers stirs up and uncovers seeds, which would otherwise be difficult or impossible for birds to access.  In this way it promotes the growth of perennial grasses and forbs which do not need to reseed every year in order to survive.

·        Grazers also remove cover for insects which may prey upon vegetation and act as parasites.  Birds then have better access to them which keeps the population down. 

·        Days later, the ‘cow patties’ will have fly larvae and other insects in them which make a particularly nutritious food source for many birds.  This particular action is important in controlling flies and other pests, which prey upon herbivorous species.

·        While foraging for grubs within the manure the birds will scratch through it and spread it around.  This makes the manure more available as a nutrition source for a wide array of plants.

·        Spreading manure also prevents stagnant ‘patties’ from killing the plants beneath them.

As demonstrated, birds are extremely important in a pastoralism.  They play a critical part in pest control and species diversity for both flora and fauna.  In newer models of poly grazing, chickens and other fowl are being used more frequently to supplement meat production, spread manure, and control pests without the use of pesticides or herbicides.

Burrowing Animals Improve Soil Conditions and Species Diversity

In natural systems, there are always burrowing animals present.  In the prairie, prairie dogs in particular play a key role in the overall health of the great planes biome.  These animals are important for aerating soil and increasing porosity.  Soil will often stratify over time and minerals become otherwise unavailable to certain plants because of factors such as root depth, inability to compete, leaching, and lithification.  In North America prairie dogs play a major role in grassland ecosystems.  Other animals such as rabbits and ground squirrels may play a major role as well.

Prairie dogs have many benefits

·        Mineral rich soil is brought to the surface and organic matter injected below through their manure, dead bodies, and nesting.

·        Their burrows provide habitat and shelter for many other animals such as burrowing owls, rabbits, snakes, smaller rodents, and ferrets.

·        Prairie dogs provide food for animals such as wolves, coyotes, badgers, hawks, owls, and ferrets.  All of which are animals that keep the population of both other rodents, and the prairie dogs them selves to a manageable level. 

·        Constant grazing pressure is applied to small areas of pasture within a prairie dog town in contrast to the taller grass of other areas.  This promotes species diversity.

·        Additional topography created by their mounds and holes creates microclimates that would otherwise not exist.  This further promotes species diversity.

·        Small areas of bare soil near the entrances to their burrows are often used by large herbivores for dust baths.  This helps clean them of parasites and protects them from biting flies and mosquitoes.

These healing actions keep the soil, topography, and species composition of grasslands in a state of flux, which promotes a high degree of diversity. These factors make burrowers a cornerstone component, which is often left out or repressed from current production models.  The perception is that they somewhat compete for or diminish food resources, when they are actually increasing the long-term viability and overall production of the system.  This is partly by the direct results of their actions, and partly through a reduction in need for inputs.

Insect Ecology on the Great Plains

No terrestrial ecosystem on Earth is without insects.  They are normally suppressed in whenever possible in the vast majority of agricultural models.  This is a mistake and in ecology based agriculture they are encouraged.  Among the most common insects in grasslands of North America are; Hymenoptera (ants, bees, and wasps), Orthoptera (grasshoppers and crickets), Diptera (flies), Coleoptera (beetles), Hemiptera (insects with sucking mouthparts), and Lepidoptera (butterflies and moths). 

Some insects stand out as having a particularly important role

·        Ants are largely responsible for the movement of nutrients to the root zone of many plants.  They are important in maintaining healthy soil texture and structure.  Their tunneling action turns the soil and increases both aeration and porosity.  Invasive earthworms have also become a major component, with both positive and negative effects being observed.

·        Dung Beetles play a major role in the distribution of nutrients.  They move large amounts of dung from concentrated areas and distribute it more evenly.  After laying their eggs within the dung balls, many species even bury them.  The actions of their larvae then further process the dung making it more available as a nutrient source for plants.

·        Many species of flies and beetles are important in the recycling and distribution of nutrients from dead animal tissue.  After consuming a carcass they scatter and redistribute these nutrients through their own dead bodies.  Flies are especially suited to this with their especially short life spans.

·        Endemic bee species play a major role in the pollination of many prairie plants.  Butterflies, beetles, and moths often play a role as well.  In some instances, an insect species may partner up with a particular plant.  The two may depend on each other completely for survival.  This makes species diversity especially crucial.

In addition to the positive effects of insects, there are also perceived negative effects

·        Parasitic flies can torment all forms of animals including humans, as well as spread disease.

·        Mosquitoes provide a huge source of disease and hardship.

·        Plagues of locust may consume huge quantities of material which causes hardship for grazing animals. 

·        Sucking insects may weaken or kill plants, which diminishes forage quality. 

However, in nature nothing is wasted.  Even ‘undesirable’ insects are either returned to the earth, or are consumed by other species.  For example, locust plagues can actually be important in especially rich years.  When there is too much plant growth, herbivores may not be able to keep up.  Hotter and more destructive fires can result from too much standing biomass as well as unfavorable shifts in species composition.  Locusts also provide especially rich bumper crops of protein for reptiles, birds, and rodents all the way up the food chain to bears, wolves, and coyotes.  Even something as seemingly destructive as the locust can end up providing more benefits than drawbacks.  Every component of the ecosystem has its role to play.

Poly-Culture and Guild Structure within Grasslands

Species diversity in plants plays a critical role in overall ecosystem health.  In arid grasslands of the American Southwest, Australia, and Africa, leguminous trees such as acacia, ironwood, and mesquite are sometimes an important component.  In different grasslands, other trees provide similar roles.  These trees do not form a closed canopy as in a forest ecosystem, but remain at a distance great enough to provide adequate lighting and resources for pasture. 

Trees and woody shrubs

·        Provide forage in times of extreme drought with both foliage, and edible pods, nuts, and fruits.

·        Provide nesting places for birds, bees, wasps, and other arboreal creatures.  Hollow trunks provide hiding places for small mammals and reptiles.

·        Furnish shade and cooler microclimates for both animals and other plants.  Woody patches or hedges provide protection from extreme drying winds or biting cold.

·        Have deep taproots which reach water far underground and make it available to surface plants that might not otherwise have access.

·        Because of their nature, leguminous trees also add nitrogen to the soil through colonies of nitrogen-fixing bacteria, which live in special structure on the roots.

Forbs and other leafy plants

·        Forage for bees and other insects.

·        Nutrients for herbivores, which grass often cannot provide.  Diversity allows for a wider array of micronutrients and phytochemicals.  Some plants fight pathogens, act as antibiotics, have powerful antioxidant effects, or aid in digestion ect…

·        Shade and living mulch to prevent the desiccation of soil.  Wider leaves block out sun and form air pockets with higher humidity and lower temperatures.  This helps in preventing evaporation and transpiration from escaping into the atmosphere.

Just as in a forest, grasslands have different layers of plants in their ‘canopy’.  Some are shade tolerant and moisture sensitive, some are tall and can handle the brutal sun.  Roots intermingle and take advantage of different nutrient profiles stratified within the soil.  Some plants like perennial grasses may be fire tolerant.  Annuals and woody shrubs may become more prevalent in areas that have not burned for some time.  Some plants respond well to heavy grazing pressure from prairie dogs or quicker grazing cycles.  Some plants exist only in damaged landscapes and facilitate the healing process.  This entire array of different flora provides a vital element of diversity which sets natural grassland apart from production agriculture and heavily managed pastures.

Perennial Grasses are the Apex Plant Species

The cornerstone of the grassland ecosystem is the perennial grass.  Perennial grass is the apex species of the pasture.  It is tenacious, its roots penetrate deeply, it is nutritious, drought and fire resistant, can survive without reseeding, and it aggressively both improves and creates new soil.  It is the analogue of ‘old growth’ in a grass-based system.  Perennial grass is encouraged in regenerative, pasture-based agriculture because of its nutrition, epic soil building capability, ergonomic ease of care, and the wildlife habitat that it provides.  The roots of these grasses have been shown to penetrate dozens of feet into the earth searching for water and nutrients.  This is not a taproot like on a tree, but a mass of finer roots with thousands of times more surface area. 

Common Perennial Grasses in the American Prairie

Short grass: Blue Grama, Buffalo Grass

Tall grass: Big Bluestem, Switch Grass, Indian Grass

Mixed Prairie: Little Bluestem, Western Wheatgrass

 Important benefits of perennial grasses

·        Drastically increased soil stability, which helps prevent erosion and the formation of gullies.  Wind erosion during drought is minimized or eliminated.

·        Extremely deep roots give greater access to both moisture and stratified bands of minerals, which would otherwise not be available.  This feature results in a very high quality nutrient profile compared to other forage species.

·        After grazing, portions of the root mass shed off and die within the soil.  As they decay, this injects carbon deep within the soil profile, effectively sequestering it.  This is the primary source of organic matter within the fertile Mollisol soils created by grasslands.

·        After decaying, root channels are left behind.  This creates spaces for the growth of new roots.  In addition, it also increases soil porosity, water retention, water infiltration, aeration, slows lithification, improves soil texture, and reduces compaction.

·        Subsurface nutrients and moisture become available to other plants through decay and capillary action within the root zone of perennial grasses.  The effects of drought are minimized and nutrient mobilization is increased.

This combination of effects creates the some of the finest agricultural soils on earth and plays a major role in keeping our carbon cycle balanced.  Oddly enough, pastoral agriculture is touted as a contributor to global warming and in production agriculture it is.  It is true that the bioconversion ratio of grass to meat is only about 10:1.  It is also true that animal’s emit carbon through breathing and digestion. However, the vast majority of grassland biomass lies below the surface.  They are essentially upside down forests.  This is where the carbon sequestration takes place and it offsets the carbon emissions of any animal activity by a huge margin.  The fact is that grassland ecosystems are among the most effective carbon sequestration tools available to man and their management requires the use of grazing animals.

Managing Pasture for both Soil and Animal Health

In rotational grazing, as in nature, herds of different herbivorous animals move through an area, which is generally subjected to heavy, albeit selective grazing upon certain plant species.  Once an area is exhausted, the animals move on to ‘greener pastures’ and the process repeats.  This may happen with several species of animals before an area is allowed to recover.  In a poly-grazing system one may choose to rotate cattle, then sheep, then goats, then chickens.  The reason for choosing which animals may be moved through an area may have to do with the species of forage present, which animals came before, and the way in which those animals graze.

The grazing habits of common livestock

·        Cattle generally eat long grass first.  This can prevent or suppress grasses from going to seed, which could shift the species profile to annuals.

·        Sheep enjoy short grasses and forbs.  They take advantage of material generally left behind by cows.

·        Goats normally browse trees/shrubs.  They also tolerate noxious weeds as well as invasive plants pasture plants like blackberry brambles, multiflora rose, and honeysuckle.  This prevents the formation of a closed canopy above the ground layer and competition from undesirable species.

·        Chickens take advantage of new shoots, seeds, and insects/grubs in both the dung and newly exposed dirt.

In rotational grazing, fencing is used to cordon off a series of paddocks.  Stocking rates of animals are generally very high and the amount of time allowed in any one paddock is unusually brief.  Animals are rotated into a new paddock after they have grazed sufficiently to prevent any one species from gaining a foothold afterwards.  This is accomplished through both direct grazing and the trampling effect incurred by high stocking rates.  Little to no long term compaction occurs and plants are not killed by constant pressure.

Afterwards, one would rest the area until it is deemed to have recovered and repeat the process.  Surface biomass again returns and shed roots grow back.  There is no set amount of time this takes and it depends completely on the pastures response.  The animals are then brought around again for another cycle, which repeats according to the needs of the farmer and the condition of the pasture.  In very healthy pastures this can happen many times over the course of a season.

This model saves time and money by not having to drive the cattle from place to place.  One just opens the gate to the next paddock and the animals find the fresh forage irresistible.  Reseeding is eliminated or diminished and no use of pesticides, herbicides, fertilizers, or other artificial methods is necessary.  Organic matter in the soil is increased and the need for irrigation diminishes. 

Fire Ecology is Essential to Species Composition

Perennial grasses are fire resistant because their perennating organs (the areas where new shoots originate) lie below the surface.  This makes fire a great tool for encouraging perennial grass to dominate in ecosystems.  A varied fire regime is always best since fires during different times of the year have drastically different effects.  A varied fire regime results in the greatest diversity of plant, invertebrate, and bird species present. 

• Dormant season fires remove litter, but encourage some undesirable species and leave bare soil.  However, they have a much less profound affect on nesting birds and invertebrates. 

• Spring fires favor warm season perennial grasses like big bluestem.  But they can also have a profound impact on invertebrate species. 

• Summer fires occur most often but are smaller in size.  They are less likely to affect birds and invertebrates. They also tend to favor perennial grasses while clearing out woody plants and trees that might otherwise get a foothold on the unburned prairie.

Irrigation through Keyline Design

Irrigation in grassland is one of the easiest things to accomplish.  In all but the driest of climates, all the rain needed falls on the property.  It’s just a matter of capturing it either in the soil, or in storage basins and ponds.  A system of range management call Keyline Design was pioneered by an Australian visionary in the 40’s named P.A.Yeomans.  It solves many of the problems faced in range management today.

In the Keyline method, one digs a slightly off-level swale at the highest possible point.  The swale is perpendicular to the slope of the land therefore it intercepts runoff as it runs downhill.  Making it slightly off level means that once runoff is captured, the water will begin to move towards a desired point such as a pond, but without enough velocity to cause erosion. 

Ponds are usually located behind earthen dams in the small draws or valleys between ridges.  One generally does not dam a perennial stream, but some do siphon water from the system out of them.  A series of swales then connect this dam to other dams in adjacent valleys.  In this way, any excess runoff simply moves laterally around the ridge to the next storage area.

In extreme precipitation events, overflow is directed to ridgelines where it spreads over a broad area, preventing erosion.  Usually the water does not travel far before then being captured by another series of swales and dams below the first.  If this is not possible then water may be directed back into permanent waterways if available.

In the areas between swales, chisel plows are often employed off contour sloping out towards ridgelines.  These plow shanks do not turn soil over as in conventional agriculture but merely create narrow slits in the soil.  These channels allow water penetrate and move it underground towards the ridges, which are generally far drier than the valley bottoms.  Chisel plows also allow lower levels of mineral soil to be inoculated by organic matter from above.  Since the earth is not turned over, organic matter does not gas off into the atmosphere as it does with conventional agriculture.  Carbon levels remain intact or are augmented.

In times of drought or dry seasons, baffles located within the walls of the earthen dams allow water to be released at a desired time.  The released water is then captured by lower swale systems where it overflows into designated areas.  Use of a flag (temporary cloth dam) is used to dam the channel causing overflow at desired points along a given swale.

In simpler systems one may chose to use perfectly level swales in closer succession. In this case the swales infiltrate water instead of moving it.  Since water naturally moves through the soil on its own, the chisel plow may not be necessary.  One can still use dams in conjunction with this method and have great success.

In this way one has all the water they need without pumping ground water or damming permanent water ways.  Emphasis is put on storing water in the soil and using the resources at hand rather than extracting from other areas.  With an initial investment, one can create a system which has great longevity and requires very little maintenance.  P.A.Yeomans original property has been around for decades and still operates perfectly.

The true magic in this method is the long term benefits it has on the surrounding ecosystems.  This may take years to be truly realized but the results can be quite profound.  Water is kept in the soil where it belongs.  Groundwater is recharged and surrounding wells generally show higher levels for longer periods of time.  Streams suffering low or seasonal flow show higher volume for longer periods, less silt, and lower levels of flooding.  Pollution downstream is decreased and utilization of nutrients onsite is increased.  Erosion is decreased or eliminated.  Springs which normally run dry last longer and new ones may form both on the property in question and on surrounding properties.  Life is restored to riparian areas and the local ecology is augmented.

Notable Practitioners of Ecosystems based Grassland Farming/Management:

Joel Salatin: http://www.polyfacefarms.com/

Darren Doherty: http://www.youtube.com/watch?v=oDMg6W95-2s

Geoff Lawton: http://www.taranakifarm.com.au/

           

Web resources:

http://www.fao.org/docrep/008/y8344e/y8344e0d.htm

http://www.farmingmagazine.com/article-2817.aspx

https://sites.google.com/site/onseedballs/native-grassland-restoration-using-seedballs

http://plainshumanities.unl.edu/encyclopedia/doc/egp.pe.030 grass species

http://plainshumanities.unl.edu/encyclopedia/doc/egp.pe.025.xml fire ecology

http://plainshumanities.unl.edu/encyclopedia/doc/egp.pe.034.xml insects

Water for Every Farm:

http://www.keyline.com.au/