Farming Systems Native Ecosystem Pasture Ecosystem Grazing and InvasivesSue Ellen Johnson PhD. Director of Agriculture and Rural Economy Piedmont Environmental Council
Pastures are communities of individual plants Usually mixtures of herbaceous perennials and annualsPasture plant communities Seasonally dynamic (warm and cool season) Competitive Aboveground: compete for light, space Below-ground: compete for water, nutrients, soilPlant community affected by: Livestock grazing, treading, manure and urine Human mowing, chemical application…
Goals for pasture: Fresh green (affordable) quality feed for livestock/horses Green space for animals to derive some nutrition and exercise Beautiful “pastoral” “bucolic” landscape Economic contribution to Piedmont farming systems
GRAZING GOALS ???Productivity per acre fenced?Productivity per unit of fertilizer?Productivity per unit labor? Gain per animal? Gain per acre?Profit per acre?Profit per year ?Profit per hour of labor?Hobby and recreation?Tax status?Pretty pasture?
In pastures: Desirable and Undesirable PlantsDesirable : Palatable, non-toxic, nutritious, high yielding, competitive plants that can tolerate trampling and repeated defoliation (and regrow) Ideally persistent, resilient, easy to establish Naturalized non-natives Natives ExoticsUndesirable: compete with desirables Limit animal performance and land productivity or adversely affect the environment Native and non-native weeds some of which are invasive
Pastures not the “native” Piedmont landscapeMostly naturalized European plant speciesmaintained through human action (?)Most pastures have diverse mixtures of plant speciesPersistent perennials and naturally reseeding annuals Warm and cool season plant species
Piedmont Forages Warm season Cool season Grasses Grasses Bermudagrass Tall fescue NWSG Orchardgrass Kentucky bluegrassPerennials Legumes Perennial Ryegrass Lespedeza Legumes Alfalfa White and Red clover(s) Grasses Grasses Annual ryegrass* Crabgrass* Bromegrasses Sorghum and Millet Small grains: Oats, Annuals wheat, triticale, rye Legumes Lespedeza Legumes Crimson clover * = naturally reseeding annual
Managing grazing to manage weeds and invasivesBasic good grazing management helps desirable plantsthrive and minimizes undesirable weeds and invasivesin Northern Piedmont pastures while increasing productivityand profitability of a pasture enterpriseDesirable plants must thrive and compete, not simply survive:Keep good, desired plants species competitive…Maintain canopy between 4-8” to keep light from reaching the ground keep soil covered to manage soil temperature and moistureMaintain canopy between 4-8” by Rotating livestock to new pastures – every 3 days once a plant is grazed allow it time to regrow Do not overstock or overgraze
For a competitive canopy: need 4x the leaf surface area relative to soil surface areaFor each square foot of soil surface: 4 square feet of leaf surface area In pastures, leaves (not stems) should make up most of the canopy most of the time.
IF mowing pasturesSet mowers at 4” (minimum)Maintain canopy between 4 and 8” Time mowing to rainfall Mow when desirable plants will rapidly regrow (before budding) Dragging? Equipment and tires transport weed seedsHave a “sacrifice” pasture (or drylot) during high stress periodsStress= drought or wet
Invasives (seed or vegetation)1. Land in favorable site2. Germinate or root3. Outcompete other plants in that site4. Reproduce
Buttercup Ranunculus sppNative and exotic spp.R. pennsylvanicus is threatenedAll are weeds in pasture: unpalatable, toxicColonizes open, disturbed sites VTLikes wet, compacted soils, low pHAvoid grazing wet areas-hoof nichesLimit by maintaining dense 4” pasturesShades out if shaded early in the season… j. riley stewart photo
Pasture micro-sites Plants (forages or weeds) fit into the micro-sites above and below ground. Depends on what seed is there.Do NOT control a pasture weed without seeding something desirable in its place.Time control to favor the desirable species as well as to eradicate the problem.
AVOID creating microsites - opportunities for invasives to invade Avoid “overgrazing” Do NOT graze below 3-4 inches Use pasture rotation or exclosure
Pasture Weeds and Forage Diversity 16 14 12 10% weeds 8 6 4 2 0 2 SP 3 SP 6 SP 9 SP Forage Diversity (# of forage types in the pasture) *Averaged over two years Soder et al. 2005
What makes a plant a pasture weed/undesirable? • Poor palatability • Poor yield • Propensity to spread- crowds out other species • Toxicity Think carefully before eliminating anything that is grazed. Any plant that is grazed (palatable) and is not toxic and is not spreading is tolerable in an average pasture.
Controlling undesirables/invasives in pastureScout [Know desirables from undesirables]Control weeds at early growth stages- before they “take over”Spray, burn, dig, mow, overseed, shade, graze…Use spot control when possible.Use plant competition to (shading and crowding, allelopathy)limit undesirable plants.Overseed an annual forage: sorghum, millet, rye, annualryegrass to reduce the vigor of some undesirablesTime and manage fertilization, seeding, grazing andmowing to favor desirables.Change soil (root) conditions: temperature and moisture fertility: nitrogen pH
Controlling undesirables/invasives in pastureMake sure a desirable species will “replace” what you arecontrolling (load the seedbank).MUST change grazing/pasture management that resulted inweed invasion in the first place to prevent recurrence! WI
Desirable vs undesirable pasture species What plants are we talking about?
YES NO Mebbe Native? Invasive? Good pasture?Nimblewill Mulhenbergia schreberi
YES NO Mebbe Native? Invasive? Good pasture?Stiltgrass: Microstegium vimineum
YES NO Mebbe Native? Invasive? Good pasture?Eastern gamagrass Tripsacum dactyloides
Pastures that are also hayed: Invasives may be more challenging.. becauseHay Market is Less tolerant of species diversity-mixed hays More opportunities for invasives…
How desirtbale plants disapper form pastures How undeairtbale palnts apread in pstures Baic graing managementWarm season and cool season plants.. Two plant canopy populations…
What not to plant because of it’s invasive potential…Careful with hay : Seeds it may introduce Hay feeding sites create invasion sites
Pasture invasives: are they spreading?Are they an economic (or health )liability ) visual or ecological problem? If ypu finmd one invasive: : Flame Herbicides etc
In an established forage field Light: energy for photosynthesisPlantsLeaves: site of photosynthesisStems: support and position the leaves to capture sunlightRoots: anchor the plant, move water and nutrients into the plant Water: carries the nutrients to the plant roots and into the plants forage plant at max growth rate is 90% water (10% DM) Soil: physically support the plant and hold nutrients and water Nutrients: combined with carbon from photosynthesis to build plant tissues, move into the plant with water
A 30-50% stand is a good legume stand. 20% stand WI 70% stand WI
Regrowth from leaf blade Pre-graze Post-graze3” Regrowth from stolon
In addition to photosynthesis, canopy is important formanaging soil cover and consequently soil temperature and soil water which effect which species grow in the pasture.
Growth Stages and Growth RatesNew shootsor seedlings Vegetative Reproductive Rapid growth SlowerSlow growthgrowth Time or age
Different livestock species Different grazing objectives…Minimumh Minimum leaf area…..eifht
Grazing and invasivesHow to think about pasture plants and weeds Ecological Niche Opportunities Displacement Replacement SEEDBANK
Nimblewill,stiltgrass, goosegrassFescue orchard grass alfalfa red clover white clover ryegrassSericeaTolerablePurpletop.. Johnsongrass Undesirabkels…Mint (s)Buttercup, burrs,Burr clover, hop cloverthistles problems beyond the pasture Pastures as invasive reservoirNatives for pastures Invasives as pasture indicatorsNWSG summer grazingNatives that are problematic in pasturesYellow crownbeard - wing-stem…Do ck(s)
Undesirable natives? Tolerable? Sericea MintsClovers Lespedeza’s Stickweed VetchesSpecies useful; or tolerable in a “native friendly” pasture…
Grazing and invasives How to think about pasture and pasture plants What are undesirable or invasive pasture species (weeds) How to manage grazing to prevent/avoid undesirable or invasive pasture species How to control undesirable or invasive plants in pastures with grazing WI
Don’t plant invasive problems; don’t create niches Prevention of invasives: What grazing systems result/favor invasives? Control and eradication of invasives