Ecology ofHigh Density or Mob Grazing Ed Rayburn Appalachian Grazing Conference March 4-5, 2011 Morgantown, WV
Pasture-Based Livestock Producers• In business harvesting solar energy.• Converting solar energy into food and fiber products for people.• Manage – plants to optimize harvest of solar energy, – animals to transfer that energy into livestock products, – cycling of mineral nutrients in the landscape – to make business socially, economically, and environmentally sustainable.• Are pasture ecosystem managers.
What we will cover• Pasture Ecosystem• Ecological principles/tools – Light interception with height and date – Tolerance to shading – Selective grazing – Stocking density• Management Goals – Toxic tall fescue management – Legume establishment – Developing soil organic matter – Substitution for bush-hogging – Animal performance (now vs. long term)
Pasture Ecosystem• Plants – producers harvest sunlight fix nitrogen cycle nutrients – forage quality & anti-quality – plant morphology grass, legume, forb, shrub, tree (succession) tall vs. short rhizome vs. bunch fibrous vs. tap root “plastic” growth habit – plant life history; perennial vs. annual
Pasture Ecosystem• Grazing animals – primary consumers (cows, sheep, goats, others) – age, production rate (maintenance, milk, finishing)• Grazing preferences – animal species vs. learned behavior – ability to selectively graze – rumen size : body size and forage preference or tolerance• Movement while grazing; cows walk 4 ways – in file / cow-path – grazing “front” at low stock densities – quite, tight “mob” at high stock density – stampede
Management Goals• Toxic tall fescue management• Legume establishment• Developing soil organic matter• Substitution for bush-hogging• Animal performance (now vs. long term)
Application to toxic tall fescue management• Establish a long regowth period to open tall fescue stand through self-shading• Over-seed forage species that tolerate long regrowth periods (may already be in stand)• Use high stock density grazing to utilize the forage, walk-in the seed or just open the stand for the desired species needed to reduce the toxic tall fescue
Species Differ in Tolerance to Long Regrowth Periods/ShadingTolerant (hay type) Intolerant (pasture type) – Smooth bromegrass – Tall fescue – Timothy – Orchardgrass – Reed canarygrass – Perennial rye grass – Quackgrass – Kentucky bluegrass – Red clover – White clover – Alfalfa – Birdsfoot trefoil – Native WS grasses
Application to legume establishment• Establish a long regowth period to open forage stand at soil level through shadingOr• Use normal rotation cycle• Overseed legume species adapted to soil and planned long-term management (at “proper” time of year)• Use high stock density grazing to utilize the forage and walk the seed into the soil
Why Is SOM Important? 50Avail. Water Holding Capacity% 45 40 35 30 25 20 15 10 5 0 0 2 4 6 8 10 SOM%
Soil Organic Matter Affected by:• Past management (fertility and grazing) – Adequate fertility (applied, recycled) stimulates plant growth – Rotational grazing to proper height stimulates SOM• Local environment (temperature rainfall) – High elevations (further north) have low temperature high rainfall beneficial to development of SOM – Low elevations (further south) have higher temperatures more SOM loss hard to keep high SOM.
What in the soil do we want to feed? (feed them and they will come)• Night crawlers for • Bacteria and fungus aeration and bacteria for soil structure – Legumes – Grass – Young grass – Older high fiber – Roots material – Roots
Application to developing SOM• Establish an appropriate regowth period to maximize root health and optimize forage growth and quality for the local environment• Use high stock density grazing at density appropriate for livestock production goals to utilize the forage, compress thatch to the ground, and distribute manure and urine evenly over landscape
Application to bush-hogging• Use high stock density grazing at heavy stocking density to utilize the forage, walk thatch and seed heads into the ground, and distribute manure and urine evenly over landscape• Know life history of plants being worked with• Consider multispecies grazing
Animal performance (now vs. long term)• Increasing nutrient requirement – Dry cow mid-trimester – Dry cow last-trimester – Early lactation cow – Stocker steer – Backgrounding calf – Dairy cow• First 4 can be made to work at times• Make animals work strategically to develop better forage for the future
Stocking Density and Time vs. Grazing Pressure/Utilization• 31 animals at 1450 lbs avg. wt.• ~45,000 lbs LW on 1.25 acres• ~36,000 lbs LW/acre• 900 lbs DMI / 24 hr at 2.5%BW DMI• 1800 lbs DMI / 48 hrs• Entry ht 10” or 2754 lbs/a• Exit FM 954 lbs/a or 2.6”
Stock Density for 24 Hours at 2.5% DMI on 10” Tall Pasture (2750 lbs DM/acre) and its Affect on Utilization and Residual Forage Height Residual Residual forage Stocking forage heightForage Ht density mass Utilization est. 10 40000 1750 0.36 5.2 10 50000 1500 0.45 4.4 10 60000 1250 0.55 3.5 10 70000 1000 0.64 2.8 10 80000 750 0.73 2.0
Healthy Soil Ecology Balance of• Food supply (organic matter with adequate macro- and micro mineral nutrients)• Physical environment above and below ground (cover and habitat at all scales)• Healthy consumers, omnivores, predators, and predators of predators (diversity)• Chemical environment (soil oxygen, pH, fertility)• Thermal and moisture environment
Management Needed to Help the System (a)• Soil pH 6.0-7.0 depending on the legume• Adequate not excessive soil P and K• Inoculate legume seed with proper bacteria• Manage nutrients on the farm – (recycle manure, urine, and organic residues)• Proper grazing management – timing and intensity suitable for the forage mixture• Proper fall grazing – develop tillers in grasses and stolons of white clovers – reduce adult clover root curculio activity
Take Home• Above ground we manage plants with animals to capture solar energy, convert it into marketable livestock products, cycle nutrients so that our pasture system can be sustainable.• This management influences soil organic matter to feed macro- and microorganisms in the soil.• This affects the soil’s physical condition, availability of macro- and micronutrients and soil moisture to plants.• Understanding how management affects the soil community assists us in our management of the entire pasture ecosystem.
High Density or Mob Grazing Can Be a Useful Management Tool• To accomplish management goals – Toxic tall fescue management – Legume establishment – Developing soil organic matter – Substitution for bush-hogging• Keep in mind animal performance (now vs. long term)• Using ecological principles/tools – Light interception with height and date – Tolerance to shading – Selective grazing – Stocking density and hoof action/treading• Stock density, utilization, and regrowth period are independent management practices with their own outcome.