Cover CropsCover Crops

Terry E. PooleTerry E. Poole

Extension AgentExtension Agent

Frederick County, MDFrederick County, MD

* Cover crops are a * Cover crops are a valuable tool in valuable tool in agricultural productionagricultural production

Defining Your PurposeDefining Your PurposeCover species selected should have many of Cover species selected should have many of

the following traits:the following traits:

*fast germination & emergence*fast germination & emergence

*competitiveness*competitiveness

*tolerance to adverse climatic and *tolerance to adverse climatic and soil conditions soil conditions

*ease of suppression*ease of suppression

*fertility benefits*fertility benefits

*low-cost establishment*low-cost establishment

What is a Cover Crop?

• A crop whose main purpose is to A crop whose main purpose is to benefit the soil or other crops in benefit the soil or other crops in one or more ways, but is not one or more ways, but is not intended to be harvested for feed intended to be harvested for feed or sale.or sale.

Benefits of Cover CropsBenefits of Cover Crops

• Cuts fertilizer billCuts fertilizer bill- “fixed” nitrogen- “fixed” nitrogen

- recycles nutrients- recycles nutrients• Reduces soil erosionReduces soil erosion• Reduces water pollutionReduces water pollution• Improves soil tilthImproves soil tilth

- physical properties of - physical properties of soil favorable soil favorable to plant growth to plant growth

Benefits of Cover CropsBenefits of Cover Crops

• Cuts herbicide costsCuts herbicide costs- mulch- mulch

- alleopathy- alleopathy• Reduces insect pestsReduces insect pests• Reduces disease organisms and Reduces disease organisms and

nematodesnematodes• Provides wildlife forage and habitatProvides wildlife forage and habitat

N Furnished by Cover N Furnished by Cover CropsCrops

alfalfa, alonealfalfa, alone 80 lb80 lb alfalfa/grass alfalfa/grass 60 lb 60 lb

ladino cloverladino clover 80 lb80 lb crimson clover crimson clover 80 lb 80 lb

red clover, alone 80 lb red clover/grass 40 lbred clover, alone 80 lb red clover/grass 40 lb

common vetchcommon vetch 50 lb lespedeza50 lb lespedeza 30 lb 30 lb

hairy vetchhairy vetch 100 lb winter peas 90 lb 100 lb winter peas 90 lb

cowpeascowpeas 40 lb soybeans40 lb soybeans 35 lb 35 lb

mostly grassmostly grass 0 lb 0 lb

Disadvantages of Cover Disadvantages of Cover CropsCrops

• Can be expensive to establishCan be expensive to establish• Can be difficult to eliminateCan be difficult to eliminate• Can become a weedCan become a weed• Can compete with your cropCan compete with your crop• Not a cash crop; lose income from Not a cash crop; lose income from

cropcrop- benefits are more indirect- benefits are more indirect• Some cover crops are more flexible Some cover crops are more flexible

than others with seeding timesthan others with seeding times

What are the goals for your Cover What are the goals for your Cover Crop?Crop?

• How long do you need it?How long do you need it?• Is it for erosion control, or other Is it for erosion control, or other

environmental protection function?environmental protection function?• Will wildlife need it for forage, or cover?Will wildlife need it for forage, or cover?• Is there a need for weed suppression?Is there a need for weed suppression?• Does the soil need organic matter?Does the soil need organic matter?• Are there pest suppression needs? What?Are there pest suppression needs? What?• Be sure to allow the cover crop time to do Be sure to allow the cover crop time to do

what it is supposed to do.what it is supposed to do.

Cover Crops and TreesCover Crops and Trees

A couple of notes:A couple of notes:� Shade from trees may stunt cover Shade from trees may stunt cover

crop growth.crop growth.� Some cover crops may compete Some cover crops may compete

with trees for moisture.with trees for moisture.� Tillage to establish cover crops can Tillage to establish cover crops can

damage tree roots and also cause damage tree roots and also cause soil compaction.soil compaction.

Cover Crop EstablishmentCover Crop Establishment

• No till seedingNo till seeding

- no till drill- no till drill

- broadcast into a standing crop- broadcast into a standing crop

- frost seeding- frost seeding• Conventional seedingConventional seeding

- plow/disk- plow/disk

- broadcast/drill- broadcast/drill

Cover Crop EstablishmentCover Crop Establishment

• Inoculate legumes Inoculate legumes

- fresh, species specific inoculant- fresh, species specific inoculant• Match species to goals and soil Match species to goals and soil

type/conditionstype/conditions• Soil test and follow recommendationsSoil test and follow recommendations• Use good, live seedUse good, live seed• Control weeds as much as possibleControl weeds as much as possible

pH Effect on Soil NutrientspH Effect on Soil Nutrients

Soil Conditions Affect Soil Conditions Affect PlantsPlants

• DroughtyDroughtyYes: alfalfa, tall fescue, reed canary, Yes: alfalfa, tall fescue, reed canary,

orchardgrass, red clover, etc. orchardgrass, red clover, etc.No: kentucky bluegrass, ryegrass, No: kentucky bluegrass, ryegrass, small grains, ladino clover, small grains, ladino clover,

etc.etc.• WetWet

Yes: tall fescue, reed canarygrass, Yes: tall fescue, reed canarygrass, timothy, p. ryegrass, b. trefoil, timothy, p. ryegrass, b. trefoil,

and and red clover red cloverNo: all the restNo: all the rest

Soil Conditions Affect Soil Conditions Affect PlantsPlants

• Low fertilityLow fertility

Yes: tall fescue, reed canarygrass, Yes: tall fescue, reed canarygrass, orchardgrass, timothy, orchardgrass, timothy,

lespedeza, red clover, lespedeza, red clover, b. trefoilb. trefoil

No: alfalfa, k. bluegrass, ladino cloverNo: alfalfa, k. bluegrass, ladino clover• Very acid (below 5.5)Very acid (below 5.5)

Yes: birdsfoot trefoil, lespedezaYes: birdsfoot trefoil, lespedeza

No: the restNo: the rest

Herbicide CarryoverHerbicide Carryover

• Sites containing row crops pose a potential Sites containing row crops pose a potential threat with herbicide carryover that could threat with herbicide carryover that could damage a new planting, or cover crop.damage a new planting, or cover crop.

• Investigate, learn what herbicides were Investigate, learn what herbicides were used; if you can’t, use a cover crop used; if you can’t, use a cover crop tolerant of carryover.tolerant of carryover.

• Chemicals such as atrazine, Treflan, Chemicals such as atrazine, Treflan, simazine, Command, Pinnacle, Pursuit, and simazine, Command, Pinnacle, Pursuit, and Sinbar all have long residual periods.Sinbar all have long residual periods.

LegumesLegumes

AlfalfaAlfalfa• Perennial legumePerennial legume• High nitrogen producer, over 80 lb/AHigh nitrogen producer, over 80 lb/A• Expensive to establishExpensive to establish- high fertility - high fertility

requirementsrequirements• Deep taproot, can be hard to killDeep taproot, can be hard to kill• Does not tolerate acidic, or wet soilsDoes not tolerate acidic, or wet soils• Seedlings are not competitiveSeedlings are not competitive• Has some pest problemsHas some pest problems

Annual SweetcloverAnnual Sweetclover

• Annual legumeAnnual legume• Poor tolerance to coldPoor tolerance to cold• Deep taprootDeep taproot• Tremendous summer growth (6 ft. Tremendous summer growth (6 ft.

July)July)• Seed in early May, rate 15 to 25 lb/ASeed in early May, rate 15 to 25 lb/A• Needs pH above 6.0Needs pH above 6.0• Excellent bee pasture (honey)Excellent bee pasture (honey)

Austrian Winter PeaAustrian Winter Pea

• Winter annual legumeWinter annual legume• Vine-like growth, similar to vetchVine-like growth, similar to vetch• High nitrogen producer, producing High nitrogen producer, producing

as much as 90-150 lb/Aas much as 90-150 lb/A• Has some disease problemsHas some disease problems• Seed at rate of 60-90 lb/A Seed at rate of 60-90 lb/A

BuckwheatBuckwheat

• Summer annual (broadleaf plant)Summer annual (broadleaf plant)• Has no frost toleranceHas no frost tolerance• Tolerates wide range of soil Tolerates wide range of soil

conditionsconditions• Grows rapidly, chokes out weedsGrows rapidly, chokes out weeds• Seed at a rate of 1 bushel/ A. from Seed at a rate of 1 bushel/ A. from

late May - Augustlate May - August• Bushel weight 48 lbBushel weight 48 lb

CowpeaCowpea

• Summer annual legumeSummer annual legume• Good short season green manure cropGood short season green manure crop• Good nitrogen “fixer”, 40 lb/AGood nitrogen “fixer”, 40 lb/A• Seed at a rate of 30 - 40 lb/ASeed at a rate of 30 - 40 lb/A• Sow after the danger of frost has Sow after the danger of frost has

passedpassed• Cowpea mixed with Cowpea mixed with

sorghumsorghum

Crimson CloverCrimson Clover• Winter annual LegumeWinter annual Legume• Adapted to light, well drained soils with Adapted to light, well drained soils with

adequate pH (above 6.0)adequate pH (above 6.0)• Beautiful colorBeautiful color• Good nitrogen producer 80 lb/AGood nitrogen producer 80 lb/A• Seed 12 - 20 lb/A in late Aug. to mid-Sept.Seed 12 - 20 lb/A in late Aug. to mid-Sept.• Susceptible to disease,especially if too Susceptible to disease,especially if too

much fall growth accumulatesmuch fall growth accumulates• Will winter kill if planted too late in fallWill winter kill if planted too late in fall

FlatpeaFlatpea• Long-lived perennial legumeLong-lived perennial legume• Released as a conservation cropReleased as a conservation crop• Not recommended as a forageNot recommended as a forage• Forms dense mat that is very competitive that Forms dense mat that is very competitive that

could suppress young trees and shrubscould suppress young trees and shrubs• Needs well drained soils and pH above 6.0Needs well drained soils and pH above 6.0• May need 2 - 3 years to become establishedMay need 2 - 3 years to become established• Requires specific inoculant; however garden pea, Requires specific inoculant; however garden pea,

sweetpea, and hairy vetch inoculant has workedsweetpea, and hairy vetch inoculant has worked• Seed 20 - 30 lb/A with perennial grass in spring Seed 20 - 30 lb/A with perennial grass in spring

or late summeror late summer

Hairy VetchHairy Vetch

• Winter annual legumeWinter annual legume• Thick vines, climbing growthThick vines, climbing growth• Great nitrogen producer, 100 lb/AGreat nitrogen producer, 100 lb/A• Best suited to well drained soilsBest suited to well drained soils• Tolerates a wide range of pHTolerates a wide range of pH• Seed 25 - 40 lb/A in AugustSeed 25 - 40 lb/A in August

Hairy VetchHairy Vetch

Mix with Mix with crimson clovercrimson clover

Mix with an annual cool Mix with an annual cool

season tall-growing grassseason tall-growing grass

Mammoth Red CloverMammoth Red Clover• Biennial legumeBiennial legume• Very good nitrogen producer, 80 lb/AVery good nitrogen producer, 80 lb/A• Tolerant of moderate drainage Tolerant of moderate drainage

conditions, heavy soils, & pH above 5.5conditions, heavy soils, & pH above 5.5• Tolerates competitionTolerates competition• Seed 8 - 15 lb/A, best seeded in spring Seed 8 - 15 lb/A, best seeded in spring

(late March to early May)(late March to early May)• Best grown for 1 yearBest grown for 1 year

Medium Red CloverMedium Red Clover• Short-lived perennial legumeShort-lived perennial legume• Most common perennial legume in Most common perennial legume in

N.E.N.E.• Very good nitrogen producer, 80 Very good nitrogen producer, 80

lb/Alb/A• Seeding rate 10 - 15 lb/ASeeding rate 10 - 15 lb/A• Seed late March to early May, or Seed late March to early May, or

mid-August to early Septembermid-August to early September

White CloverWhite Clover

• Perennial legumePerennial legume• Ladino clover is a medium to tall varietyLadino clover is a medium to tall variety• Common clover is more low growingCommon clover is more low growing• Widely adapted, prefers higher pH 6.4Widely adapted, prefers higher pH 6.4• Long-lived with little maintenanceLong-lived with little maintenance• Not very competitive with grasses Not very competitive with grasses

unless managedunless managed• Seed 5 - 7 lb/A, late March to early MaySeed 5 - 7 lb/A, late March to early May

Yellow-Blossom Yellow-Blossom SweetcloverSweetclover

• Biennial legumeBiennial legume• Blooms in late springBlooms in late spring• Excellent bee pasture (honey)Excellent bee pasture (honey)• Deep, strong taprootDeep, strong taproot• Provides good weed control (alleopathic)Provides good weed control (alleopathic)• Will over-winterWill over-winter• Seed 12 - 15 lb/A, in late April to early Seed 12 - 15 lb/A, in late April to early

MayMay

GrassesGrasses

Annual RyegrassAnnual Ryegrass

• Winter annual grass Winter annual grass (can establish itself through (can establish itself through

reseeding)reseeding)• Germinates quicklyGerminates quickly• Vigorous, competitiveVigorous, competitive• Tolerates acidity (above 5.5), low fertility, Tolerates acidity (above 5.5), low fertility,

and poor drainageand poor drainage• Forms dense cover, sod can create short Forms dense cover, sod can create short

term planting problemsterm planting problems• Seed 25 - 32 lb/A, mid-Aug. to mid-Sept.Seed 25 - 32 lb/A, mid-Aug. to mid-Sept.

BarleyBarley• Winter annual grass (small grain)Winter annual grass (small grain)• Not as tall as other small grains, but Not as tall as other small grains, but

does produce an abundance of growthdoes produce an abundance of growth• Not tolerant of wet soils, or late planting Not tolerant of wet soils, or late planting

(past mid-Oct. depending on the (past mid-Oct. depending on the season)season)

• Seed 48 - 96 lb/A, mid-Sept. to early Seed 48 - 96 lb/A, mid-Sept. to early Oct.Oct.

• Bushel weight 48 lbBushel weight 48 lb

Cereal RyeCereal Rye• Winter annual grassWinter annual grass• Grows rapidly in spring, deep rootedGrows rapidly in spring, deep rooted• Very tolerant of low fertility and pH, does Very tolerant of low fertility and pH, does

respond to fertilityrespond to fertility• Used as weed suppressing mulchUsed as weed suppressing mulch• Reported to have some alleopathy, could be a Reported to have some alleopathy, could be a

problem with some small-seeded cropsproblem with some small-seeded crops• Most winter hardy of annual grassesMost winter hardy of annual grasses• Tall, stemmy, slow to breakdownTall, stemmy, slow to breakdown• Best at recovering (recycling nutrients)Best at recovering (recycling nutrients)• Seed 60 -120 lb/A, in late Sept. - late Nov.Seed 60 -120 lb/A, in late Sept. - late Nov.

OrchardgrassOrchardgrass• Long-lived perennial grassLong-lived perennial grass• Competes will in mixture with other Competes will in mixture with other

grasses and legumesgrasses and legumes• Excellent cover for wildlifeExcellent cover for wildlife• Preferred conservation cover for fallow Preferred conservation cover for fallow

fields, helps to keep weeds out of fieldfields, helps to keep weeds out of field• Easy to establishEasy to establish• Seed 25 - 35 lb/A alone, late Aug. to early Seed 25 - 35 lb/A alone, late Aug. to early

Sept., or mid-March to late AprilSept., or mid-March to late April

Sorghum and SudangrassSorghum and Sudangrass• Summer annual grassesSummer annual grasses• Includes Sudex, sorghum x sudangrassIncludes Sudex, sorghum x sudangrass• Tall growing, living mulchTall growing, living mulch• Produces an abundance of dry matterProduces an abundance of dry matter• Growth can be tough to deal withGrowth can be tough to deal with• Has some alleopathic propertiesHas some alleopathic properties• Seed can contain some johnsongrass Seed can contain some johnsongrass

hybridshybrids• Seed 30 - 40 lb/A after the danger of frost Seed 30 - 40 lb/A after the danger of frost

has passedhas passed

Spring OatsSpring Oats• Summer annual grassSummer annual grass• Used primarily as a companion cropUsed primarily as a companion crop• Will out-compete weedsWill out-compete weeds• Great for quick growthGreat for quick growth• Fall plantings have survived mild Fall plantings have survived mild

winterwinter• Seed 32 - 64 lb/A mid-March thru AprilSeed 32 - 64 lb/A mid-March thru April• Bushel weight 32 lbBushel weight 32 lb

TimothyTimothy• Perennial grassPerennial grass• Least competitive of grasses, easily Least competitive of grasses, easily

choked out by competitionchoked out by competition• Tolerant of low fertility, low pH, and Tolerant of low fertility, low pH, and

poorly drained soilspoorly drained soils• Seed is very small, can easily be planted Seed is very small, can easily be planted

too deeptoo deep• Seed 12 - 22 lb/A alone, late Aug. to Seed 12 - 22 lb/A alone, late Aug. to

early October. Spring seeding risky.early October. Spring seeding risky.

Winter WheatWinter Wheat

• Winter annual grassWinter annual grass• Tall growing, living mulchTall growing, living mulch• Can produce an abundance of dry Can produce an abundance of dry

mattermatter• Seed at a rate of 60 - 120 lb/A, Seed at a rate of 60 - 120 lb/A,

from October 5 to early Novemberfrom October 5 to early November• Bushel weight 60 lbBushel weight 60 lb

Grass/Legume MixturesGrass/Legume Mixtures

• Perennial SeedingPerennial Seeding

medium red clover, or white clovermedium red clover, or white clover++

annual or perennial ryegrass, orannual or perennial ryegrass, or

orchardgrass, ororchardgrass, or

timothytimothy

Grass/Legume MixturesGrass/Legume Mixtures

• Seeding for annual coverSeeding for annual cover

spring oats + mammoth red spring oats + mammoth red cloverclover

small grain + crimson cloversmall grain + crimson clover

small grain + hairy vetchsmall grain + hairy vetch

barley + crimson cloverbarley + crimson clover

Agencies Who Can Help Agencies Who Can Help With Cover CropsWith Cover Crops

• Maryland Department of Natural Maryland Department of Natural Resources - MD DNRResources - MD DNR

• Natural Resources Conservation Natural Resources Conservation Services - NRCSServices - NRCS

• Maryland Department of Agriculture Maryland Department of Agriculture - MDA- MDA

• Maryland Cooperative Extension - Maryland Cooperative Extension - MCEMCE

Resource PublicationResource Publication

• Managing Cover Crops ProfitablyManaging Cover Crops Profitably to order write:to order write: Cover Crops Handbook Cover Crops Handbook

Sustainable Agriculture PublicationsSustainable Agriculture PublicationsUSDAUSDA

342 Aerospace Center 342 Aerospace CenterWashington, D.C. Washington, D.C.

20250-220020250-2200

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