Cover crops 101- How

and why to get started

Eileen Kladivko, Agronomy Dept., Purdue Univ.

Tom Kaspar, USDA-ARS, Ames, IA

Barry Fisher, USDA-NRCS, Indianapolis, IN

Cover crops in the Midwest

Why cover crops?

Many potential benefits- soil health, crop

productivity, water quality

Why not used by everyone yet?

Some risks and challenges, learning curve,

time constraints, costs, no short-term

economic gains

Rationale for cover crops

A living, growing plant at times of year

when we normally have nothing

growing.

Capture sunlight, feed soil organisms,

sequester carbon, trap and recycle

nutrients, improve soil health

Make better use of the resources and

time available!

7 Month “Brown Gap” for soybean and corn, fallow period

Cover crop grows and takes up N during

some of that normally fallow season.

This would shrink the “brown gap” and

keep the land green for longer time.

Cover crops are part of a system!

Different potential benefits and

challenges for each type of cover crop

Must adapt cropping system, including

nutrient mgmt, NT (tillage) system,

manure, pest mgmt, crop rotation

Learning curve—need to do homework!

Outline for this morning

Discuss cover crop types and benefits

Considerations and checklist for getting

started in cover crops

Suggest a low-risk introductory

approach to integrating cover crops into

a corn-soybean rotation

How select cover crops?

What is your main purpose?

What is your cropping / tillage system?

Current cash crop and next cash crop?

No-till, strip till, or other systems?

What time windows are available?

How will you seed the cover crop?

Soil types, climate, drought, manure, herbicide

carryover, or other local considerations?

MCCC tool can help with these!—come to next session!

Grasses

Brassicas

Legumes

What are potential benefits?

What is your main purpose?

Nitrogen scavenger (trap N that would

otherwise leach away)

Save N for later use by cash crop

Decrease N loss to drainage water

Nitrogen producer (legume)

Fix atmospheric N2 for use by plants

Benefits and Purpose (2)

Reduce erosion

Improve soil health

Build soil organic matter

Increase biological activity and diversity

Improve aggregation

Build macropores, permeability, deeper

rooting, reduce compaction

Buffer soil from variable weather

Tap root extended another 18+ inches

beyond the end of tuber. These roots

are probably of more benefit for soil

structure and permeability than the

tuber itself.

Benefits and Purpose (3)

Conserve soil moisture

Recycle nutrients

Weed control, pest suppression

Extra forage

Increase crop yields over long term,

and decrease year-to-year variability

Cover crops and N cycling

Legumes—biological N fixation

How much N fixed? and released?

and when?

Non-legumes—How much N trapped?

and released? and when?

N-scavenging crops

Amount of biomass produced is key to

nutrient uptake—good stand, rapid growth

Age/stage of plant when killed, determines

N%, C:N, plant composition, and therefore

decomposition rate (along with weather!)

Huge challenge!

Cereal rye, annual ryegrass, wheat, oats,

barley, triticale

Residue Addition and N AvailabilityA

vail

. S

oil

N

Time

High carbon

residues added

Immobilization (tie-up) Mineralization

(release of N)

Residue Addition and N AvailabilityA

vail

. S

oil

N

Time

Low carbon

residues added

No Immobilization (tie-up) Mineralization

(release of N)

Organic material C:N ratio

Newspaper 120:1

Wheat straw 80:1

Corn stover 57:1

Rye cover crop, anthesis 37:1

Rye cover crop, vegetative 26:1

Hairy vetch cover crop 11:1

Soil microbes (average) 8:1

C:N ratios of common organic residues

C:N ratios wider than 25:1 cause N immobilization for some time

period. If utilizing covers with wide C:N ratios, then should either:

• allow time for decomposition before high N-using crop (corn)

• apply extra starter N

• don’t choose high C:N covers before corn

Resources

www.mccc.msu.edu

2nd Edition now available!

Purdue Extension Education Store

1-888-EXT-INFO

www.the-education-store.com

Cover Crop Selector Tools(link on left sidebar)

Checklist for Cover Crops

• Initial Considerations

– Goals

– Educate yourself

– Current system

– Planning

• Spring / Summer before

• Late Summer / Fall

• Winter / Early Spring

• Spring

Initial Considerations – Goals

• Why do I want to do this?

• Cover crops are a long-term investment.

• More growth, more diversity, and bigger

window are good but don’t push that at first –

don’t go for the home run first time at bat

• Low hanging fruit – erosion control

Initial Considerations – Educate

Yourself

• Talk to other farmers – local is better

• Go to field days, workshops, and meetings

• Judge internet and magazine information

based on where you are and where they are

– newest, most exciting, or most sensational

information probably needs to “season” or

“age” a bit

• Experiment – learn as you go – adapt

Where is Iowa ?

Where does your information

about cover crops come from?

Initial Considerations – What’s

Your Current System?

• Current crop rotation and maturities

• Current tillage system – no-till and strip till

easier and leave more time

• Herbicide and weed control program -

residuals

• Equipment and logistics

http://extension.psu.edu/plants/crops/soil-management/cover-crops/herbicide-

persistence/herbicide-carryover-table

Initial Considerations - Planning

• Start small & easy – be ready ahead of time

• Decide on cover crop species – use

something somebody else has grown – single

species – available/inexpensive

• Planting plan – when/who/how/rate – backup

plan

• Herbicide/termination plan – when/who/how –

backup plan – err on side of caution

• Main crop planting - modifications

• Halftime adjustments – other team is weather

Spring / Summer Before

• Adjust residual herbicide plan if needed

• Plant targeted fields early

• Order cover crop seed well in advance

• Arrange for cover crop seeding services or

equipment

Later Summer / Fall

• Monitor main crop progress

• If aerial seeding before harvest, monitor

weather and soil moisture conditions

• If planting after harvest, harvest as soon as

possible and have cover crop planting

equipment and seed ready to go

• Adjust plan as weather and calendar date

dictate

Winter / Early Spring

• Look at stand, winter survival, and amount of

growth the previous fall

• Consider soil profile water storage

• Consider next summer’s residual herbicide

program for next fall’s cover crop

• Plan or arrange for cover crop termination

Spring

• Consider weather, soil profile water storage,

cover crop growth, and projected planting

times with regard to when to terminate

• Scout fields for insect pests. Consider

chemical control at time of cover crop

termination if necessary. Allow host-free

period if necessary – 2 weeks. Scout again.

• When planting cash crop monitor planting

and make adjustments to ensure proper seed

depth, seed furrow closure, and to prevent

residue pinning.

Midwest Cover Crops Council Website

http://www.mccc.msu.edu/

Cover Crops

…Strategies for a

Corn-Soybean Rotation

Strategically…

CC should complement the following crop

What about Corn?

Strategically…

CC should complement the following crop

…Which is better?

Corn into:

High Carbon

(Corn/Wheat)

…or

High N (Protein)

Cover Crop

(Clover/Peas)

Strategically…

CC should complement the following crop

Corn into:

High Carbon

(Corn/Wheat)

…or

High N (Protein)

Cover Crop

(Clover/Peas)

Strategically…

CC should complement the following crop

To Raise N (Protein)

Add: Clover/Peas

and consider:

Oats, Oilseed

Radish, Rapeseed

Strategically…

CC should complement the following crop

Corn into a mix:

High Carbon (Rye)

Provides Erosion

Control

plus

Moisture Savings

Strategically…

CC should complement the following crop

Corn into a mix:

High Protein

Provides Optimum

Nutrient Release

Strategically…

CC should complement the following crop

Corn into

a Mix of:

High C (carbon)

and

High N (Protein)

Strategically…

What about Soybeans?

Do Soybeans

need N ?

…Sure, but

they

capture

their own!

Strategically…

Soybeans do well into a high carbon Cover Crop.

…Why?

Weed Control, Late Season Water and Nutrient Cycling

Strategically…

CC should match desired C:N Ratio

Material C:N Ratio

rye straw 82:1

wheat straw 80:1

oat straw 70:1

corn stover 57:1

rye cover crop (anthesis) 37:1

rye cover crop (vegetative) 26:1

mature legumes 25:1

Balanced Microbial Diet 24:1

daikon radish 19:1

crimson clover 17:1

ryegrass (vegetative) 15:1

young alfalfa 13:1

hairy vetch cover crop 11:1

soil microbes (average) 8:1

Go

od

fo

r C

orn

Go

od

fo

r S

oyb

ea

n

Strategically…

Planning the system

1. Drill or VT

Cereal Rye into

Corn Stalks

Strategically…

Planning the system

1. Plant a short

season

Soybean into

the Rye

(preferably early

in the season)

Strategically…

Planning the system

3. Plant a low C:N

mix into or after

Soybean

Strategically…

Planning the system

4. NT Corn into a

Biologically

Active

High Function

Soil

Strategically…

Planning the system

5. Enjoy The Rewards of

Soil Health!