Carmen Fernholz operates a 360 acre farm near Madison, Minnesota.
His 300 tillable acres, primarily silty clay soil, are almost entirely
organic certified with the exception of some experimental acres.
Fernholz grows oats, flax, corn, barley, rye, soybeans, wheat, hairy vetch,
alfalfa, nitro alfalfa, red clover, berseem clover, and yellow sweet clover.
He also raises feeder to finish hogs, not certified organic.
Fernholz' weed management practices include tillage, crop rotation,
and monitoring of soil conditions. With over a quarter century of
experience in farming without chemicals, he has developed a system of mechanical
weed management using a rotary hoe, a front mounted cultivator, and careful
observation of weeds and their response to moisture and temperature.
Fernholz says his soybean fields are "invariably spotless." (Frazeur,
1997) He estimates he saves at least $10 per acre over the use of
chemical herbicides.
Rotary Hoe
Fernholz usually rotary hoes within 5 days of planting corn or soybeans.
When determining whether it's time to hoe, he scratches the soil surface
to a depth of an inch or more. If white, hair-like foxtail grass
roots are visible, he considers it the most opportune time to hoe.
He keeps his tractor speed between 8 and 10 miles per hour. Rotary
hoeing can be repeated several days to a week later, but it must be managed
carefully to limit damage to the emerged crop.
Side View of a Rotary Hoe
Close-up of Rotary Hoe Tines Showing the Operating Depth
Spring Tooth Harrow
The spring tooth harrow has 14" long, spring-loaded teeth that remove the
early emerging weeds in both corn and soybeans. Fernholz travels
down the crop rows at about 6 mph prior to crop emergence but much slower
after the crop has emerged. The harrow seems much more effective
in dry top soils than in moist soils. Because of this characteristic,
the spring tooth harrow complements the rotary hoe, which is a bit more
effective if the soils are on the wetter side. Given the brief period
each Spring during which the harrow may be used, the farmer can expect
to need several years to learn to use it effectively.
Spring Tooth Harrowing Before Corn Emergence
Close Up of Spring Tooth Harrow
The Front/Rear Mount Cultivator
The front/rear mount cultivator is a Fernholz original. Using the
front mount enables Fernholz to drive more accurately and maneuver the
cultivator more precisely for a finer job of cultivating. He sets
the front mount shovels to run close to the rows, but that can cause weeds
to be missed in 30" rows. He considered adding more shovels, but since
there is a minimum of space with which to work, more shovels between the
rows would make it difficult for old crop residue to pass through freely.
Consequently, Fernholz added the rear mounted cultivator. The rear
cultivator removes the weeds missed by the front cultivator and eliminates
the tracks from the drivers. It needs little attention because its
shovels are spaced farther from the rows and Fernholz is already driving
quite straight because of the front mount.
Front and Rear Row Crop Cultivators
Rear View of Row Crop Cultivators
For further details of Fernholz' weed management techniques, see the
publication, Steel
in the Field.
Sources
MOFIE, 2001. "MOFIE Network," Minnesota Organic Farmers' Information
Exchange Network, Southwest Research and Outreach Center, Lamberton, MN,
May 2001.
Frazeur, Andrea. "Spreading the Sustainable Story," AURI AG Innovation
News, July 1997.
SAN, 1997. Steel in the Field: A Farmers Guide to Weed Management
Tools, Greg Bowman, ed., Sustainable Agriculture Network, 1997.
All photos courtesy of Carmen Fernholz.
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