Local Update for PEC Supporters in Charlottesville & Albemarle County
Grazing and Invasives
1. Farming Systems Native
Ecosystem
Pasture Ecosystem
Grazing and Invasives
Sue Ellen Johnson PhD. Director of Agriculture and Rural Economy
Piedmont Environmental Council
2. 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…
3. 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
4. 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?
5. 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
6. Pastures not the “native” Piedmont landscape
Mostly naturalized European plant species
maintained through human action (?)
Most pastures have diverse mixtures of plant species
Persistent perennials and naturally reseeding annuals
Warm and cool season plant species
7. Piedmont Forages
Warm season Cool season
Grasses Grasses
Bermudagrass Tall fescue
NWSG Orchardgrass
Kentucky bluegrass
Perennials 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
9. Managing grazing to manage weeds and invasives
Basic good grazing management helps desirable plants
thrive and minimizes undesirable weeds and invasives
in 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
10. 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.
11. IF mowing pastures
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 periods
Stress= drought or wet
12. Invasives (seed or vegetation)
1. Land in favorable site
2. Germinate or root
3. Outcompete other plants in that site
4. Reproduce
16. Buttercup Ranunculus spp
Native and exotic spp.
R. pennsylvanicus is threatened
All are weeds in pasture: unpalatable, toxic
Colonizes open, disturbed sites VT
Likes wet, compacted soils, low pH
Avoid grazing wet areas-hoof niches
Limit by maintaining dense 4” pastures
Shades out if shaded early in the season…
j. riley stewart photo
17. 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.
18. AVOID creating microsites - opportunities for invasives to invade
Avoid “overgrazing”
Do NOT graze below 3-4 inches
Use pasture rotation or exclosure
19. 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
20. 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.
21. Controlling undesirables/invasives in pasture
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.
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
Time and manage fertilization, seeding, grazing and
mowing to favor desirables.
Change soil (root) conditions:
temperature and moisture
fertility: nitrogen pH
22. Controlling undesirables/invasives in pasture
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
45. 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…
46. How desirtbale plants disapper form pastures
How undeairtbale palnts apread in pstures
Baic graing management
Warm season and cool season plants.. Two plant canopy populations…
47. What not to plant because of it’s invasive potential…
Careful with hay :
Seeds it may introduce
Hay feeding sites create invasion sites
48. Pasture invasives: are they spreading?
Are they an economic (or health )liability ) visual or ecological problem?
If ypu finmd one
invasive: :
Flame
Herbicides etc
49. In an established forage field
Light: energy for photosynthesis
Plants
Leaves: site of photosynthesis
Stems: 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
51. A 30-50% stand is a good legume stand.
20% stand
WI
70% stand
WI
52. Regrowth from
leaf blade
Pre-graze Post-graze
3”
Regrowth
from stolon
53. In addition to photosynthesis, canopy is important for
managing soil cover and consequently soil temperature
and soil water which effect which species grow in the pasture.
54. Growth Stages and Growth Rates
New shoots
or seedlings Vegetative Reproductive
Rapid
growth
Slower
Slow growth
growth
Time or age
56. Grazing and invasives
How to think about pasture plants and weeds
Ecological Niche
Opportunities
Displacement
Replacement
SEEDBANK
57. Nimblewill,
stiltgrass, goosegrass
Fescue orchard grass alfalfa red clover white clover ryegrass
Sericea
Tolerable
Purpletop.. Johnsongrass
Undesirabkels…
Mint (s)
Buttercup, burrs,
Burr clover, hop clover
thistles problems beyond the pasture
Pastures as invasive reservoir
Natives for pastures
Invasives as pasture indicators
NWSG summer grazing
Natives that are problematic in pastures
Yellow crownbeard - wing-stem…
Do ck(s)
58. Undesirable natives?
Tolerable?
Sericea Mints
Clovers Lespedeza’s Stickweed
Vetches
Species useful; or tolerable in a “native friendly” pasture…
59. 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
61. Don’t plant invasive problems; don’t create niches
Prevention of invasives:
What grazing systems result/favor invasives?
Control and eradication of invasives