Pasture Ecosystem
Farming Systems Native Ecosystem
Grazing and Invasives
Sue Ellen Johnson PhD. Director of Agriculture and Rural Economy Piedmont Environmental Council
Pastures are communities of individual plants Usually mixtures of herbaceous perennials and annuals
Pasture plant communities Seasonally dynamic (warm and cool season) Competitive
Aboveground: compete for light, space Below-ground: compete for water, nutrients, soil
Plant 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 Plants
Desirable : 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 Exotics
Undesirable: 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 landscape Mostly naturalized European plant species maintained through human action (?)
Warm and cool season plant species
Most pastures have diverse mixtures of plant speciesPersistent perennials and naturally reseeding annuals
Warm season GrassesBermudagrassNWSG
LegumesLespedeza
GrassesCrabgrass*Sorghum and Millet
LegumesLespedeza
Perennials
Annuals
Piedmont Forages
Cool season GrassesTall fescue OrchardgrassKentucky bluegrassPerennial RyegrassLegumesAlfalfa White and Red clover(s)
GrassesAnnual ryegrass*BromegrassesSmall grains: Oats, wheat, triticale, rye
LegumesCrimson clover
* = naturally reseeding annual
Fescue
Orchardgrass
Bluegrass
Soil level
Crabgrass
Basic good grazing management helps desirable plants thrive and minimizes undesirable weeds and invasivesin Northern Piedmont pastures while increasing productivity and profitability of a pasture enterprise
Desirable 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 moisture
Maintain 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
Managing grazing to manage weeds and invasives
For a competitive canopy: need 4x the leaf surface area relative to soil surface area
For 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.
Set 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 seeds
Have a “sacrifice” pasture (or drylot) during high stress periodsStress= drought or wet
IF mowing pastures
Invasives (seed or vegetation) 1. Land in favorable site2. Germinate or root3. Outcompete other plants in that site4. Reproduce
Blaser VPI 1986
Grazing (mowing) heights affect pasture species composition
“Pioneer” species. Invades open, disturbed spaces.Limit by maintaining dense 4” minimum pastures.
Spotted knapweed Centaurea maculosa
j. riley stewart photo
VT
Buttercup Ranunculus spp
Native and exotic spp. R. pennsylvanicus is threatened All are weeds in pasture: unpalatable, toxic
Colonizes open, disturbed sitesLikes wet, compacted soils, low pH
Avoid grazing wet areas-hoof nichesLimit by maintaining dense 4” pasturesShades out if shaded early in the season…
Pasture micro-sitesPlants (forages or weeds) fit into the micro-sitesabove 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
Forage Diversity (# of forage types in the pasture)*Averaged over two years
2 SP 3 SP 6 SP 9 SP02468
10121416
% w
eeds
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 toxicand is not spreading is tolerable in an average pasture.
Use plant competition to (shading and crowding, allelopathy) limit undesirable plants. Overseed an annual forage: sorghum, millet, rye, annual ryegrass to reduce the vigor of some undesirables
Scout [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.
Change soil (root) conditions: temperature and moisture
fertility: nitrogen pH
Controlling undesirables/invasives in pasture
Time and manage fertilization, seeding, grazing and mowing to favor desirables.
Make sure a desirable species will “replace” what you are controlling (load the seedbank).
MUST change grazing/pasture management that resulted in weed invasion in the first place to prevent recurrence!
WI
Controlling undesirables/invasives in pasture
Desirable vs undesirable pasture species
What plants are we talking about?
Nimblewill Mulhenbergia schreberi
YES NO MebbeNative?Invasive?Good pasture?
Stiltgrass: Microstegium vimineum
YES NO MebbeNative?Invasive?Good pasture?
Eastern gamagrass Tripsacum dactyloides
YES NO MebbeNative?Invasive?Good pasture?
Eastern gamagrass
Switchgrass
NWSG Pastures- designated for warm seasonNOT grazed during winter monthsrotationally grazing May-September Attentive management: 4-6” residualBig bluestem, Indiangrass, Eastern Gamagrass, Switchgrass,Buffalo grass
Johnsongrass Sorghum halepense
YES NO MebbeNative?Invasive?Good pasture?Locally invasive?
To eliminate palatable species: continuously grazeAllow unrestricted access.
Crabgrass
YES NO MebbeNative?Invasive?Good pasture?
Digitaria sanguinalis
Stickweed or Wingstem or Yellow Crownbeard: Verbesina occidentalis
YES NO MebbeNative?Invasive?Good pasture?Locally invasive?
YES NO MebbeNative?Invasive?Good pasture?
Foxtail (Setaria spp. )
Kentucky BluegrassPoa pratensis
Goosegrass Eleusine indica
Broomsedge Andropogon virginicus
Weeds = management problems
Undesirable: low yielding, marginal palatability;indicates compaction
Undesirable: unpalatable; indicates low pH
Lespedeza cuneata“Sericea”
http://www.cottoncrc.org.au/files/ed326f7a-15f4-4f74-9c8f-994401342942/Burr%20medic.jpg
Hop clover Trifolium campestre
YES NO MebbeNative?Invasive?Good pasture?
Burr clover
RyegrassLolium perenneLolium multiflorum
J. Koivisto
Crown vetch Coronilla varia
Hairy vetch Vicia villosa
YES NO MebbeNative?Invasive?Good pasture?
Tall fescue Festuca arudinacea
YES NO MebbeNative?Invasive?Good pasture?
Grazing as a means to control invasives
Mixed species grazing and invasives
7:30 am
Pigweed stems stripped bare of leaves after 20 hours high density goat stocking
Diverse pasture mixtures more competitive with weeds
Henbit (Lamium amplexicaule)
X
www.anr.ext.vt.edu/lawnandgarden/turfandgardentips/pdfs/nimblewill_bermuda_id.pdf
http://www.caf.wvu.edu/~forage/tutorial/
www.fcps.edu/islandcreekes/ecology/
www.extension.umn.edu/forages/pdfs/Native_Legumes.pdf
http://www.gardenorganic.org.uk/organicweeds/weed_management/show_wman.php?id=10 pigs
Extras
Pastures that are also hayed: Invasives may be more challenging.. because
Hay Market is Less tolerant of species diversity-mixed hays More opportunities for invasives…
How desirtbale plants disapper form pasturesHow undeairtbale palnts apread in pstures Baic graing management
Warm 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 introduceHay 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: :FlameHerbicides etc
In an established forage field
Light: energy for photosynthesis
PlantsLeaves: site of photosynthesisStems: support and position the leaves to capture sunlight Roots: 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
Managing Grass-Legume Mixtures
WI
A 30-50% stand is a good legume stand.
WI
20% stand
70% stand
3”
Pre-graze Post-graze
Regrowth from stolon
Regrowth from leaf blade
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.
Time or age
Slowgrowth
Rapidgrowth
Rela
tive
Gr o
wt h
Rat
e
Growth Stages and Growth Rates
New shootsor seedlings Vegetative Reproductive
Slowergrowth
Different livestock species Different grazing objectives…
Minimum heifht
Minimum leaf area…..
Grazing and invasives How to think about pasture plants and weeds
Ecological Niche
OpportunitiesDisplacementReplacementSEEDBANK
Nimblewill, stiltgrass, goosegrassFescue orchard grass alfalfa red clover white clover ryegrassSericea
Tolerable Purpletop.. Johnsongrass
Undesirabkels…Mint (s)Buttercup, burrs, Burr clover, hop cloverthistles
Natives that are problematic in pastures Yellow crownbeard - wing-stem…Do ck(s)
Natives for pasturesNWSG summer grazing Invasives as pasture indicators
problems beyond the pasturePastures as invasive reservoir
Clovers Mints Stickweed
Undesirable natives? Tolerable?
SericeaLespedeza’s
Vetches
Species 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
Prevention of invasives: What grazing systems result/favor invasives?
Control and eradication of invasives
Don’t plant invasive problems; don’t create niches
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