Cover Crops Terry E. Poole Extension Agent Frederick County, MD
Defining Your Purpose Cover species selected should have many of the following traits: *fast germination & emergence *competitiveness *tolerance to adverse climatic and soil conditions *ease of suppression *fertility benefits *low-cost establishment
What is a Cover Crop? • A crop whose main purpose is to benefit the soil or other crops in one or more ways, but is not intended to be harvested for feed or sale.
Benefits of Cover Crops • Cuts fertilizer bill - “fixed” nitrogen - recycles nutrients • Reduces soil erosion • Reduces water pollution • Improves soil tilth - physical properties of soil favorable to plant growth
Benefits of Cover Crops • Cuts herbicide costs - mulch - alleopathy • Reduces insect pests • Reduces disease organisms and nematodes • Provides wildlife forage and habitat
N Furnished by Cover Crops alfalfa, alone 80 lb alfalfa/grass 60 lb ladino clover 80 lb crimson clover 80 lb red clover, alone 80 lb red clover/grass 40 lb common vetch 50 lb lespedeza 30 lb hairy vetch 100 lb winter peas 90 lb cowpeas 40 lb soybeans 35 lb mostly grass 0 lb
Disadvantages of Cover Crops • Can be expensive to establish • Can be difficult to eliminate • Can become a weed • Can compete with your crop • Not a cash crop; lose income from crop - benefits are more indirect • Some cover crops are more flexible than others with seeding times
What are the goals for your Cover Crop? • How long do you need it? • Is it for erosion control, or other environmental protection function? • Will wildlife need it for forage, or cover? • Is there a need for weed suppression? • Does the soil need organic matter? • Are there pest suppression needs? What? • Be sure to allow the cover crop time to do what it is supposed to do.
Cover Crops and Trees A couple of notes: • Shade from trees may stunt cover crop growth. • Some cover crops may compete with trees for moisture. • Tillage to establish cover crops can damage tree roots and also cause soil compaction.
Cover Crop Establishment • No till seeding - no till drill - broadcast into a standing crop - frost seeding • Conventional seeding - plow/disk - broadcast/drill
Cover Crop Establishment • Inoculate legumes - fresh, species specific inoculant • Match species to goals and soil type/conditions • Soil test and follow recommendations • Use good, live seed • Control weeds as much as possible
Soil Conditions Affect Plants • Droughty Yes: alfalfa, tall fescue, reed canary, orchardgrass, red clover, etc. No: kentucky bluegrass, ryegrass, small grains, ladino clover, etc. • Wet Yes: tall fescue, reed canarygrass, timothy, p. ryegrass, b. trefoil, and red clover No: all the rest
Soil Conditions Affect Plants • Low fertility Yes: tall fescue, reed canarygrass, orchardgrass, timothy, lespedeza, red clover, b. trefoil No: alfalfa, k. bluegrass, ladino clover • Very acid (below 5.5) Yes: birdsfoot trefoil, lespedeza No: the rest
Herbicide Carryover • Sites containing row crops pose a potential threat with herbicide carryover that could damage a new planting, or cover crop. • Investigate, learn what herbicides were used; if you can’t, use a cover crop tolerant of carryover. • Chemicals such as atrazine, Treflan, simazine, Command, Pinnacle, Pursuit, and Sinbar all have long residual periods.
Alfalfa • Perennial legume • High nitrogen producer, over 80 lb/A • Expensive to establish - high fertility requirements • Deep taproot, can be hard to kill • Does not tolerate acidic, or wet soils • Seedlings are not competitive • Has some pest problems
Annual Sweetclover • Annual legume • Poor tolerance to cold • Deep taproot • Tremendous summer growth (6 ft. July) • Seed in early May, rate 15 to 25 lb/A • Needs pH above 6.0 • Excellent bee pasture (honey)
Austrian Winter Pea • Winter annual legume • Vine-like growth, similar to vetch • High nitrogen producer, producing as much as 90-150 lb/A • Has some disease problems • Seed at rate of 60-90 lb/A
Buckwheat • Summer annual (broadleaf plant) • Has no frost tolerance • Tolerates wide range of soil conditions • Grows rapidly, chokes out weeds • Seed at a rate of 1 bushel/ A. from late May - August • Bushel weight 48 lb
Cowpea • Summer annual legume • Good short season green manure crop • Good nitrogen “fixer”, 40 lb/A • Seed at a rate of 30 - 40 lb/A • Sow after the danger of frost has passed • Cowpea mixed with sorghum
Crimson Clover • Winter annual Legume • Adapted to light, well drained soils with adequate pH (above 6.0) • Beautiful color • Good nitrogen producer 80 lb/A • Seed 12 - 20 lb/A in late Aug. to mid-Sept. • Susceptible to disease,especially if too much fall growth accumulates • Will winter kill if planted too late in fall
Flatpea • Long-lived perennial legume • Released as a conservation crop • Not recommended as a forage • Forms dense mat that is very competitive that could suppress young trees and shrubs • Needs well drained soils and pH above 6.0 • May need 2 - 3 years to become established • Requires specific inoculant; however garden pea, sweetpea, and hairy vetch inoculant has worked • Seed 20 - 30 lb/A with perennial grass in spring or late summer
Hairy Vetch • Winter annual legume • Thick vines, climbing growth • Great nitrogen producer, 100 lb/A • Best suited to well drained soils • Tolerates a wide range of pH • Seed 25 - 40 lb/A in August
Hairy Vetch Mix with crimson clover Mix with an annual cool season tall-growing grass
Mammoth Red Clover • Biennial legume • Very good nitrogen producer, 80 lb/A • Tolerant of moderate drainage conditions, heavy soils, & pH above 5.5 • Tolerates competition • Seed 8 - 15 lb/A, best seeded in spring (late March to early May) • Best grown for 1 year
Medium Red Clover • Short-lived perennial legume • Most common perennial legume in N.E. • Very good nitrogen producer, 80 lb/A • Seeding rate 10 - 15 lb/A • Seed late March to early May, or mid-August to early September
White Clover • Perennial legume • Ladino clover is a medium to tall variety • Common clover is more low growing • Widely adapted, prefers higher pH 6.4 • Long-lived with little maintenance • Not very competitive with grasses unless managed • Seed 5 - 7 lb/A, late March to early May
Yellow-Blossom Sweetclover • Biennial legume • Blooms in late spring • Excellent bee pasture (honey) • Deep, strong taproot • Provides good weed control (alleopathic) • Will over-winter • Seed 12 - 15 lb/A, in late April to early May
Annual Ryegrass • Winter annual grass (can establish itself through reseeding) • Germinates quickly • Vigorous, competitive • Tolerates acidity (above 5.5), low fertility, and poor drainage • Forms dense cover, sod can create short term planting problems • Seed 25 - 32 lb/A, mid-Aug. to mid-Sept.
Barley • Winter annual grass (small grain) • Not as tall as other small grains, but does produce an abundance of growth • Not tolerant of wet soils, or late planting (past mid-Oct. depending on the season) • Seed 48 - 96 lb/A, mid-Sept. to early Oct. • Bushel weight 48 lb
Cereal Rye • Winter annual grass • Grows rapidly in spring, deep rooted • Very tolerant of low fertility and pH, does respond to fertility • Used as weed suppressing mulch • Reported to have some alleopathy, could be a problem with some small-seeded crops • Most winter hardy of annual grasses • Tall, stemmy, slow to breakdown • Best at recovering (recycling nutrients) • Seed 60 -120 lb/A, in late Sept. - late Nov.
Orchardgrass • Long-lived perennial grass • Competes will in mixture with other grasses and legumes • Excellent cover for wildlife • Preferred conservation cover for fallow fields, helps to keep weeds out of field • Easy to establish • Seed 25 - 35 lb/A alone, late Aug. to early Sept., or mid-March to late April
Sorghum and Sudangrass • Summer annual grasses • Includes Sudex, sorghum x sudangrass • Tall growing, living mulch • Produces an abundance of dry matter • Growth can be tough to deal with • Has some alleopathic properties • Seed can contain some johnsongrass hybrids • Seed 30 - 40 lb/A after the danger of frost has passed
Spring Oats • Summer annual grass • Used primarily as a companion crop • Will out-compete weeds • Great for quick growth • Fall plantings have survived mild winter • Seed 32 - 64 lb/A mid-March thru April • Bushel weight 32 lb
Timothy • Perennial grass • Least competitive of grasses, easily choked out by competition • Tolerant of low fertility, low pH, and poorly drained soils • Seed is very small, can easily be planted too deep • Seed 12 - 22 lb/A alone, late Aug. to early October. Spring seeding risky.
Winter Wheat • Winter annual grass • Tall growing, living mulch • Can produce an abundance of dry matter • Seed at a rate of 60 - 120 lb/A, from October 5 to early November • Bushel weight 60 lb
Grass/Legume Mixtures • Perennial Seeding medium red clover, or white clover + annual or perennial ryegrass, or orchardgrass, or timothy
Grass/Legume Mixtures • Seeding for annual cover spring oats + mammoth red clover small grain + crimson clover small grain + hairy vetch barley + crimson clover
Agencies Who Can Help With Cover Crops • Maryland Department of Natural Resources - MD DNR • Natural Resources Conservation Services - NRCS • Maryland Department of Agriculture - MDA • Maryland Cooperative Extension - MCE
Resource Publication • Managing Cover Crops Profitablyto order write: Cover Crops Handbook Sustainable Agriculture Publications USDA 342 Aerospace Center Washington, D.C. 20250-2200