Finding the best fit cover crops on your

organic farm

Dr. Joel Gruver

WIU – Agriculture

j-gruver@wiu.edu

crop rotationsHistorically

revolved around LEGUMES

A typical view 50 years ago

Typical rural landscape

in IA and IL today

>90% of landsurface

in corn or soybeans

Typical amounts of nitrogen

fixed by legumes

Alfalfa 150-300+

Soybeans 150-250

Red clover 75-200

Hairy vetch 75-200

Other annual forage

legumes50-150

(lbs/ac/yr)

Soybean seeds

normally contain

25-50% more N

than was fixed

within their

nodules

Hairy Vetch3,260 lbs of DM/ac

141 lbs of N/ac

133 lbs of K/ac

18 lbs of P/ac

52 lbs of Ca/ac

18 lbs of Mg/ac

http://www.ncl.ac.uk/tcoa/files/breakcrops_orgagr.pdf

Finding the best fit for CCs within a crop rotation

:

3 broad goals of

ecological

managementActivation

AugmentationConservation

Terminating spring planted oats with a soil finisher

~ 3 weeks before planting corn

GOAL = biological activation

• Problems and opportunities for over 500 crop

sequences

• Characteristics of more than 60 crops and 70 weeds

• Crop diseases hosted by over 80 weed species

• Modes of transmission for 250 diseases of 24 crops

• Thirteen sample four- and five-year vegetable and

grain crop rotations Managing Crop Rotation Chart

with key tasks & steps

•Sample worksheets and calculations

• Step-by-step procedure for determining crop rotation

plans

Overview of book contents

Rotations

should evolve

not revolve

• Fast germination and emergence

• Competitiveness

• Tolerance to adverse climatic & soil

conditions

• Ease of suppression/residue

management

• Fertility/soil quality benefits

• Low-cost

What to Look For in A Cover Crop

Cover

Crops

Adapted from Magdoff and Weil (2004)

Cover crops have many effects!

Feed

livestock

? ?

Increase

management

Host

pests

Become

a weed

Prevent

soil

drying

Dry out soil

excessively

Interfere w/

equipment

performanceSuppress

crop growth

Tie up N

Add cost

Cover

Crops

Adapted from Magdoff and Weil (2004)

Not all are positive

Grazing brassicas, clovers, small grains, ryegrass, sorghum-sudan

Nutrient Cycling brassicas, small grains, annual ryegrass

Bio-drillingbrassicas, sugarbeet, sunflower,

sorghum-sudan sweet clover, alfalfa

N-fixation clovers, vetches, lentil, winter pea, chickling vetch, sun hemp,

cowpea, soybean

Bio-activation/fumigation brassicas, sorghum-sudan, sun hemp, sesame

Matching specific objectives with species

How will I seed the cover crop?

What will soil temperature and moisture conditions be like?

What weather extremes and field traffic must it tolerate?

Will it winterkill in my area?

Should it winterkill to meet my goals?

What kind of regrowth can I expect?

How will I kill it and plant into it?

Will I have the time to make this work?

What’s my contingency plan—and risks—if the

cover crop doesn’t establish or doesn’t die on schedule?

Do I have the needed equipment and labor?

Key considerations

Start planning now for next fall!

Best single source of info on cover crops is FREE!

regularly updated blog on

cover crop management

There are lots of opportunities following small grains!

Hu

nte

r

Have you tried any forage brassicas?

#1

opportunity

to make

cover crops

pay

Hairy vetch can be successfully planted after

wheat harvest. On the two occasions (out of 18

site-years of the WI Cropping System Trial)

when the red clover failed to establish well,

hairy vetch produced an average of 115 lbs N/a

providing an excellent ―back-up plan‖.

July/August plantings of vetch or

other cover crops are riskier than

frost seeding clover.

the most tried and true

cover cropping system

in the Midwest region

Frost-seeded clover

Sweet

clover

Mustard

http://calshort-lamp.cit.cornell.edu/bjorkman/covercrops/spring-mustard.php

Klaas and Mary Martens,

organic innovators in

Central NY State, are

reporting excellent results

with frost-seeded

confectionary mustard

ahead of dry beans

Be realistic about potential

cover crop challenges

Are you equipped to handle a situation like this?

10’ Howard Rotavator tilling ~ 3” deep with C blades

Complete kill after 1 pass

and 2 days of sun

Typical weather in 2009/2010 :-<

Where are the soybeans??

Traditional organic weed management

often comes up short during wet years

A strong stand of cereal rye was incorporated

~ 2 weeks before these soybeans were planted

Organic No-till?

Rodale roller

Cultimulcher

Less

weed seed

germination

…but few

options for

weed

termination

Early July 2009

Early August 2009

Early November 2009

Plot yields ranged from 51.6 to 58.6 bu/ac

No significant differences between systems

November 2010

Plot yields ranged from 42-52 bu/ac

Significant foxtail pressure

but almost no broadleaf weeds

Soybean health experiment – 6 locations across IL

Mustard

Rapeseed

Canola

Cereal rye

November 2010

Bio-strip till

September 2008

Attempt #2September 2009

Tillage radish on 30” rows with oats on 7.5” rows

November 2009

Radish planted on 30‖ rows using milo plates

in mid-August 2010

Ontario, Canada

Radish planted in

volunteer cereal rye

November 2010

Annual ryegrass variety trial

November 2010

Annual ryegrass

w/crimson clover

Wheat + radish trial

November 2010

What is a cover crop cocktail??

Sunflowers + soybeans+ buckwheat

July 17 planting

July 29 planting

Cover crops generally require more management

than manure or purchased nutrient amendments

Many of the 2008

profiles were

updated in 2010!