Organic weed management in field crops Proven and new approaches
Dr. Joel Gruver Western Illinois University
PRECISION
Currently only available upon request Will soon be downloadable
from our website
http://www.wiu.edu/cbt/agriculture/farms/organic/
High tech precision vs. attention to detail
In 2012, I witnessed a new level of attention to detail
Why is there rapeseed on the edge of this bean field?
Prior to working with Gary, I was under the impression that cultivation had limited ability to control in-row weeds and
wondered if in-row cover crops might be of value
Steel in the Field shows how today's implements and
techniques can control weeds while reducing—or
eliminating—herbicides.
In practical language, Steel in the Field presents what
farmers and researchers have learned in the last 20 years about cutting weed-control
costs through improved cultivation tools, cover crops and new cropping rotations.
Row crop farmer profiles
STEEL in the FIELD
Dryland farmer profiles
The shovels leave soil roughly ridged with some incorporation of residue. The pass exposes roots of fall
growing weeds such as quackgrass and field bindweed to winter’s wrath. He makes a second fall pass if weeds begin to
regrow, or if quackgrass is a problem.
Weed control, however, starts in October. “The last cultivation in fall is our first weed management for
spring,” Jacobson says. He uses 4- inch beavertail shovels (pointed at the bottom, wide at the top) on his chisel plow.
To stimulate weed growth, he harrows in late April as soon as soil dries out.
His Herman stiff-tine harrow has round tines about 5/16ths of an inch in diameter..
He controls the subsequent weed flush with a field cultivator outfitted with 9-inch sweeps. He makes a second pass if weed pressure is heavy and if he can
delay planting.
Terry uses a Seed-Right hoe drill
Crop Rotation on Organic Farms: A Planning Manual provides an
in-depth review of the applications of crop rotation-including
improving soil quality and health, and managing pests, diseases, and
weeds. Consulting with expert organic farmers, the authors share
rotation strategies that can be applied under various field
conditions and with a wide range of crops.
Crop Rotation on Organic Farms is most applicable to farms in the Northeastern United States and
Eastern Canada but is worth a look
3 broad goals of ecological
management
Activation
Augmentation Conservation
Suppression
A nice flush of weeds ready for termination
What can we do to maximize this flush?
Not all tillage operations have the same effect
Terminating spring planted oats with a soil finisher ~ 3 weeks before planting corn
GOAL = biological activation and weed suppression
Planting into poorly digested red clover residues
Corn seed was planted into moisture but ~ 25% of one hybrid and > 50% of another
was lost to seed rot and insect feeding
We had near perfect stands in every other field
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
Who is sleeping in your soils?
Do any of you have experience with flame weeding?
Dennis Leutke in MN and Larry Shrock in MO are experts
Terminating weeds without awakening sleeping seeds
Cropping system strategies vs.
Direct control strategies
Effective strategies disrupt weed life cycles
Cropping system strategies
Crop rotation Tillage rotation Cover cropping
Crop management Fertility management Manure management
Field/equipment/seed sanitation
Optimizing crop growth to maximize crop competitiveness
-Select a well adapted variety (maximum leafiness and rate of canopy closure) -Delay field work (soil must be warm enough for rapid crop emergence) -Prepare a good seed bed (start out clean) -Reduce row spacing and increase populations -Row fertilizer?
Preventive management
• Flush soil seed bank with fallow periods
• Walk crops
• Employ alternative equipment for mowing, pulling weeds
• Weedy crops -> forage or cover crops
Hopefully it doesn’t really take 15 years for preventative management to pay
Well established fall planted small grains are very competitive
against weeds
Do you see a cover crop?
Do you see a cover crop?
Frost seeded clover
the most tried and true cover cropping system in the Midwest region
Sweet clover
Mustard
Frost seeding options
Klaas and Mary Martens, organic innovators in Central
NY State, are reporting excellent results with frost-
seeded confectionary mustard ahead of dry beans
Preceded by radish :-<
Results would probably be opposite during a normal or wet year
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
Pioneering work by Jeff Moyer at the
Rodale Institute
has sparked considerable interest
in organic no-till across the country
Innovation all across the US
Innovative farmers have built lots of
interesting looking rollers
Some times its best to make do with what you already have
Cultimulcher Front mounted Rodale roller
October 2008
Cereal rye drilled at 60 lbs/a in late August
Our experience is that a strong stand of rye is much more important than roller design
Early June 2009
1 week later
~2 weeks after planting
July
August late September
Early November 2009
No-till, bio-strip-till and conventional till plot averages ranged from 51.6 to 58.6 bu/ac
No significant differences between systems
We planned a ridge-till vs. no-till comparison for 2010
May 2010
July 2010
We drilled into standing rye without rolling on 6/7 because of a very narrow window between rains.
We ended up knocking down the ridges and were not able to plant these plots until 7/4 due to excessive wetness
November 2010
Plot yields ranged from 42-52 bu/ac
Significant foxtail pressure but almost no broadleaf weeds
June 2011
August 2011
November 2011
The NT bean plots yielded ~10 bu more than the best
tillage system plots
April 2012
Planting into 5-6’ tall rye on May 11
Double drilled with 4” offset
June 2012
Our 2012 NT bean yields ranged from ~ 30 to ~ 60 bu/a
60-70 bu/a
In July 2012, we undercut several fields of small grain stubble using a Hinniker no-till cultivator and a tractor with RTK guidance
Fallow strip Cover crop cocktail no-till drilled after
undercutting
Triple S mix Sunflowers, Soybeans & Sunn hemp
We started growing sunflowers in 2010 when >300% of normal precip in May, June and July kept us out of
the fields planned for corn
July 17 planting
We could hardly believe it but this field of sunflowers planted on 7/29 actually matured.
Sunflowers are now a weed clean-up crop in our rotations
Precision Mechanization
Vehicle control
Steering (Autosteer)
Steering
(assisted steering)
Implement control
Steering
(passive)
Steering
(active)
Planter row unit control
230 bu/ac in 2010
Strip intercropping
Jacob
Exciting developments are happening but the foundation of successful weed management in organic row crops will continue to be healthy crops and healthy soil