Finding the best fit cover crops in
organic farming systems
Dr. Joel Gruver
WIU – Agriculture
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!
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