Mid‐Atlantic Dairy Grazing Conference
Grass‐Legume Mixtures:
Dairy grazing is high value grazing.
Persistence (seedbank or root system), Quality (digestibility)
Productivity per acre and per animal
Warm season Grasses Bermudagrass Dallisgrass NWSG
Legumes Lespedeza
Grasses Crabgrass*
Sorghum and Millet Legumes
Lespedeza Forage Soybeans Cowpeas
Arrowleaf Clover Perennials
Annuals
North Carolina Forages
Cool season Grasses Tall fescue Orchardgrass Kentucky bluegrass Legumes
Alfalfa
White clover(s) Red clover Birdsfoot Trefoil Grasses
Annual ryegrass*
Prairie grass (Matua)*
Small grains: Oats, wheat, triticale, rye Legumes
Crimson clover
* = naturally reseeding annual
Perennials, annuals grasses, legumes, forbs…….
persistent and transient species
Most pastures and hayfields have mixtures of species.
Mixtures are the “natural order” of nature. Mixtures should be managed as a diverse competitive community of desirable plants to provide year‐round pasture. Three‐six species dominate most mixtures.
late summer early fall
late fall
early spring
late spring early summer
Stored Forages
Pasture
early winter Multiple seasons
Photosynthesis as many days of the year as possible
Pasture Weed Contamination
Forage Diversity (# of forage types in the pasture)
*Averaged over two years
2 SP 3 SP 6 SP 9 SP 0
2 4 6 8 10 12 14 16
% weeds
Soder et al. 2005
inflorescence peduncle
stipule
nodule
stolon
taproot node
internodes
stem leaflets
petiole leaf
node
stipule
Lateral roots Adventitious roots
Forage Legume
Nitrogen
:N fertilizer costs Organic N source
Soil organic matter
“Biodiversity“‐ pollinator habitat
Legumes contribute to high value grazing dairies
N as amines moves directly from nodule
into the roots
NC: 120 lbs/acre/yr
Good nodulation is the result of roots finding the correct rhizobia bacteria. Using inoculants is insurance that legume roots will come into contact with the correct nodule forming bacteria.
What limits nitrogen fixation?
• Acid soils (low pH)
• Poor fertility‐ lack of P, K, Mo, B, S
• Compaction‐ poor aeration (no pore space)
• Absence of live inoculating rhizobia bacteria‐ no root nodules
• Wrong type of rhizobia – inactive root nodules
• Flooded or droughted or overheated soils
• Nitrogen fertilizer
INOCULATE
Nodulation apparent 3‐6 weeks after planting/green‐up Check for effective nodulation
Active nitrogen‐fixing nodules are “pink” inside [muddy brickyard pink]
Check at least 3 sites in every field.
Dig, do not pull roots!
A good number is 20 nodules per plant.
Healthy plants are not proof of nodulation!
Check nodulation every season.
Source?
Correct Soil Fertility:
LIME to reduce soil acidity as measured by “pH”
minimum = 6 maximum = 7.2 target = 6.5
Lime effects complicated, but lime is best insurance that 9 Soil nutrients will be available
9 Legume nodulation will be successful
Good clover stands possible (old dry lots) where nutrients And organic matter have accumulated over years‐ even if pH below 6, but above 5.2
P‐K‐S‐Mg as recommended
Species N Fixed N Value in $/acre/year
lb/A/year N cost =
45 cents /lb
N cost = 60 cents /lb
Alfalfa 150-250 68-113 90-150
Red Clover 75-200 34-90 45-120 White Clover 75-150 34-68 45-90
Economics: N fertilizer price vs. seed cost vs. lbs forage/acre Carrying capacity: Cash flow constraints
Forage quality: Digestibility Æ Milk
Digestibility ÆIntakeÆ Milk
Legumes contribute to high value grazing dairies
Beef steer performance as affected by white clover in KY-31 tall fescue.
(Hoveland et al., 1981).
Average daily gain, lbs. Gain/Acre, lbs.
Tall fescue 1.06 374
Tall fescue + clover 1.53 582
Table 2. Potential milk production per acre of pasture from monoculture grasses and mixtures with kuraclover or birdsfoottrefoil.
Nitrogen fertilizer Grass
or legume Kentucky bluegrass Smooth bromegrass Orchardgrass
pounds milk / acre
100 lbs/acre N 2,166 3,234 3,361
300 lbs/acre N 3,708 4,534 4,363
Kura clover 5,507 5,095 4,318
Birdsfoot trefoil 4,751 5,435 4,467
Milk production per acre was estimated from forage yield and quality with the MILK90 spreadsheet (Undersander, et al., 1993). Values are means from data collected over 3 years at Arlington and Lancaster, WI.
The neutral detergent fiber (NDF), acid detergent fiber (ADF), and Net Energy Lactation (NEL) content of pastures in the Northeast (average + standard deviation) (adapted from Rayburn 1994 and Sirois 1995).
Pasture NDF ADF TDN NEL NEM
Grass1 53±10 28±4 70±5 0.67±0.08 0.74±0.09
Mixed mostly grass2 48±10 27±4 69±5 0.69±0.08 0.73±0.09 Mixed mostly legume3 44±10 28±4 69±5 0.68±0.08 0.73±0.09
Legume4 31±10 23±4 70±5 0.76±0.08 0.74±0.09
Corn 46±6 26±4 70±3 0.73±0.03 0.68±0.06
1 Grass= less than 15% legume
2Mostly grass= 15-49% legume
3Mostly legume = 50-85% legume
4Legume= Greater than 85% legume
NCSU Budget Forage Costs, $/ton of DM
GEOFF BENSON, ARE, NCSU
Crop $2006 $2008
Perennial cool season grass ‐ clover pasture 45 53
Rye/ryegrass 60 69
Perennial cool season grass pasture 60 71
Corn silage 67 74
Small grain silage 101 112
Hay, cool season grass 124 139
NOTE: Costs based on DM lbs ‐ not quality [protein and digestibility]
Digestible DM is important to high value dairy grazing
Managing Grass‐Legume Mixtures
Nutrient intake is the goal Water available
Pasture palatability Species mix
mix‐match diets Rotations
Search time; bite size weeds?
Fresh un‐fouled pasture
Fertility?
WI A 30‐50% stand is a good legume stand.
WI
20% stand
70% stand
Blaser VPI 1986
Grazing heights: Initiation and residual stubble heights
3”
Pre‐graze Post‐graze
Regrowth from stolon Regrowth from
leaf blade
Jim Green
Two species mixtures not as effective as more diverse mixtures
Botanical composition of organic and conventional alfalfa with and without prairiegrass
Seasonal surpluses and shortfalls
?
? ?
Steve Washburn
Selecting, designing and evaluating a grass‐legume mix:
Adding a legume to an established grass stand:
1. More grazing, protein, digestibility, intake, nitrogen, cover?
2. Fill forage gap or shortfall 3. Other species in the mix
4. Management level or skill and inputs
Pasture micro‐sites
Mixtures of plants (forages and weeds) fit into the micro‐sites
above and below ground.
Overseeding, spot seeding drill or broadcast most economic.
Remove herbage prior to seeding.
Arkansas [Jennings group] “concentrated overseeding”
Usual drill or broadcast Seed concentrated in strips on 25% of total field area
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Better stands of legume; equal nitrogen contribution and distribution
Spot seed, Interseed, Overseed whenever possible
MINIMIZE TILLAGE
Which legumes?
Perennials ?
White, Red Clovers or alfalfa or BFT Annuals?
Clovers, Soybeans, Cowpea, Lespedeza
W PT RS RG O D BFT F
F RS O BFT RG W D PT
PT O W D RS BFT RG F
BFT PT O F RG D W RS
BFT W RG PT O D RS F
PT RS F RG BFT W O D
BFT W D PT O RS RG F
W BFT RG O D PT F RS
F D RS W O BFT PT RG
Cool Season Legume Overseed of Established Grasses 2008 Replication 1
Lane
Superintendent Home
Offices
Spring Planted Plots
Waynesville, NC Prairie
Orch1 Orch 2 TF KY31 KYBG Mix1 Mix 2 Natrl
Testing pasture mixtures on your farm:
Testing in an established perennial forage field:
Leave most of the field in the established forage as “background”
for comparison. Test overseeding : Overseed 3‐to‐6 strips through the established forage.
Established forage Established forage Established forage Established forage
Test strip Test StripTest Strip Test Strip
MINIMUM TEST :
Repeat strips of each mixture or variety at least three times; not in same order across the field. At least two strips are of each mixture are needed; 4‐
to‐6 strips of each mixture is ideal.
Comparing more than 3 mixtures or species or varieties is complicated.
MIX 1 MIX 2 MIX 3 Mix 1
Mix 2 Mix3
What Doesn’t Work: Using one area of the field for each variety or practice.
Why: Each third of the field will have a different yield even if the same mix or legume is planted.
Mix 1 Mix 2 Mix 3
What Doesn’t Work: Using one field for each variation.
Why: Each field will have a different yield even with the same practice.
Better to put half of each field into each mix or overseeded variety.
PRACTICE or MIXTURE ONE PRACTICE or MIXTURE TWO
Field A Field B
What Doesn’t Work:
Testing one practice one year and another variety the next year.
Comparing different years is comparing different years, not practices.
Whether in the same or different fields not a useful comparison.
WHY: Each year will have different management and weather.
A fair comparison is NOT possible, unless you have detailed historic records for the field and repeat multiple years and fields
Year 2011 Year
2012
Clover 1 Clover 1 Mix 1 Mix 1
Clover 1 Mix 1
Testing new options: Side‐by‐side comparisons Use at least two fields for an honest evaluation!
Examples:
Overseeded white clover
Five species mix: orchard, prairiegrass, crabgrass, two white clovers and an BFT Commercial mixture
Variety 1 Variety 3 Variety 2 Variety 1 Variety 2 Variety 3
Variety 3 Variety 2 Variety 1
Variety 2 Variety 1 Variety 3
Map: Using two or more permanent points in or near the field.
Measure actual distances to fixed points. Markers in the field alone are not as reliable.
