Finding the best fit cover crops in

organic farming systems

Dr. Joel Gruver

WIU – Agriculture

j-gruver@wiu.edu

A typical view 50 years ago

Typical rural landscape

in IA and IL today

>90% of landsurface

in corn or soybeans

This is not

going to work

for organic

farming

systems!

What do modern organic farming systems look like?

Where do cover crops fit in modern organic farming systems?

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

Cover crops are not the missing puzzle piece(s)

in current crop rotations!

• 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

• 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

Excellent information on integrating cover crops with agronomic crops

http://ohioline.osu.edu/sag-fact/pdf/0009.pdf

3 broad goals of

ecological

management

Activation

Augmentation Conservation

& deactivation

underpin effective organic

farming systems

Organic farm in NW Missouri

More “conservation” is needed!

Terminating spring planted oats with a soil finisher

~ 3 weeks before planting corn

biological activation (enhanced nutrient cycling)

& deactivation (weed suppression)

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

performance Suppress

crop growth

Tie up N

Add cost

Cover

Crops

Adapted from Magdoff and Weil (2004)

Not all are positive

Avoid haphazard use of cover crops

What am I

supposed to do

now?

Develop a plan to increase beneficial effects

while minimizing negative effects

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

Nutrient scavenging/cycling

brassicas, small grains, annual ryegrass

Bio-drilling

brassicas, 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

Weed suppression

brassicas, sorghum-sudan, cereal rye, buckwheat

Matching specific objectives with species

Hunter

Ethiopian

cabbage Winfred

Have you tried any forage brassicas?

http://www.jennifermackenzie.co.uk/2005/12/brassicas.html

#1

opportunity to

make cover

crops pay

crop rotations Historically

revolved around LEGUMES

Soybean seeds

often contain

>25% more N than

was fixed within

their nodules

Do all legumes add N to the soil?

Typical amounts of nitrogen

fixed by legumes

Alfalfa 150-300+

Soybeans 150-250

Hairy vetch 75-200

Red clover 75-150

Other annual forage

legumes 50-150

(lbs/ac/yr)

Hairy Vetch 3,260 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

Only legumes ―fix‖ nitrogen

All cover crops capture and recycle plant essential nutrients

Best single source of info on cover crops is FREE!

Best collection of information on cover cropping in the Midwest

• 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

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?

Additional considerations

Start planning now for next fall!

Effective multi-tasking or cover crop chaos???

Mixes can add

both performance

and challenges!

Do you see any cover crops??

Frost seeded

red clover

the most tried

and true

cover cropping

system

in the Midwest

region

There are lots of opportunities following small grains!

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.

Sweet

clover

Mustard is not the only

option for frost

seeding

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

Pacific Gold

slower to mature but

more biomass

IdaGold

matures faster but

less biomass

Mustard variety trial at the WIU Organic Research farm

(Spring 2011)

Mustards (and other brassicas) are very

responsive to N availability

Mustards (and other brassicas) are easy to

kill and decompose rapidly

Sunflowers perform well planted mid-summer

following spring planted cover crops

July 17 planting

July 29 planting Not recommended

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 :-<

Are you familiar with the fence post principle?

Zone of maximum biological

activity and rapid residue decay

Deeper burial does not optimize decay but sends weed

seeds into deep dormancy and brings deeply dormant

weed seeds to the surface where they germinate slowly

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

JD 730 Air-Disk drill on Jack Erisman’s farm in Pana, IL

Jack uses this rig to drill soybeans on 6" rows (~ 280,000/ac)

while also dropping about 2 bushel of rye and some

micronutrients

Dramatic impact of timing and weather on weed pressure

Planted 1 week later after a heavy rain

Lots of weeds but very few

towering monsters of maternity :->

provided some weed

suppression and no yield

loss for 2 reps

40 lbs/a of cereal rye seeded over

soybean rows at planting

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

About 1 month ago

Soybean health experiment – 6 locations across IL

Mustard

Rapeseed

Canola

Cereal rye

November 2010

Does anyone recognize this cover crop?

A different approach to organic no-till beans

Soybeans no-till drilled

into pasture after scalping

with a flail mower

Bio-strip till

September 2008

Attempt #2 September 2009

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

November 2009

Radish planted on 30‖ rows (~ 2.5 lbs/a)

using milo plates in mid-August 2010

Close up of wide row radishes in fall 2010

Cultivating wide row radishes in fall 2010

Ridged radishes in spring 2011

Planting popcorn on radish

ridges in spring 2011

Field appearance after 1 round

Ontario, Canada

Recently cultivated radishes in fall 2011

Annual ryegrass variety trial

November 2010

A. ryegrass roots

grow deep even

on poorly drained

soils

A. ryegrass is

hard to kill with

tillage

Wheat + radish trial

November 2010

1lb/a of radish - > 2.5 bu yield gain

Cover crops generally require more management

than manure or purchased nutrient amendments

Updated in 2010!

Successful organic

farming takes a high

level of skill and will!