I didn't want to overload you with information, but as the discussion
continues on cover crop management and incorporation, I am compelled to
refer you to another SAN publication: Steel in the Field: A Farmer's Guide
to Weed Management Tools. 1997. From the index,
(http://www.sare.org/steel/item7.htm) cover crops are mentioned on at
least 35 of the 128 pages in the book.
Steel in the Field addresses 37 tillage tools in enough detail that you will
know when and how to use each one to manage weeds AND to manage cover crops
in many cases! The book includes case studies of 22 U.S. farmers, most of
whom use various combinations of tillage, cover crops, and agri-chemicals to
manage weeds while improving their soil.
I excerpt from one farmer case study below.
Other excerpts from the book are available on the web at
To order the $18 book--and what a deal for 128 pages of in-the-field,
down-to-earth information--see http://www.sare.org/steel/item8.htm
CREDIT CARD ORDERS NOW ACCEPTED--despite what some of our literature still
says. Call 802-656-0494 to order by credit card.
Really, I'm not a salesperson, but an agronomist and technical information
specialist for sustainable agriculture, coordinating the Sustainable
Agriculture Network, the outreach arm of the USDA SARE program and the
sponsor of sanet-mg. My role and objective is to produce and disseminate
practical information about sustainable agriculture to farmers and
Excerpt from Steel in the Field: A Farmer's Guide to Weed Management Tools
Copyright 1997 by the Sustainable Agriculture Network
A sustainable transition takes the right metal
* 1,800 acres (all certified organic) * 80-cow, cow/calf beef herd *
legumes: sweet clover, red clover, alfalfa * row crops:
corn, edible soybeans * orchardgrass/clover/alfalfa pasture mix * mulch
tillage with disking * cover crops: rye, buckwheat,
hairy vetch * small grains: oats, wheat, canola, rye, triticale
Weed management highlights
Strategies: Minimum tillage... cover crops... seven-year, flexible crop
rotation... mechanical cultivation
Tools: Flexible-chain harrow... high-residue rotary hoe... three cultivators
(low-residue, high-residue, maximum
residue)... heavy and light tandem disks
Jack Erisman uses both conventional and unconventional practices to protect
his soil resources and production
potential. Terraces he built long ago now seem less important to him than
thick-rooted cover crops for erosion
control. He has a wide inventory of tillage and cultivation tools not
because he likes to use them, but so he can use
each one as little as possible to its best advantage.
Building his soil's biological quality and its loose, crumbly structure are
his primary goals and serve as the foundation
for successful integrated systems of non-chemical weed control and crop
production. His on-farm research is geared
to finding the tillage-cutting building blocks of organic, no-till systems
for soybeans and other cash crops.
Erisman has been practicing conservation tillage for more than 25 years,
having used a modified ridge-till system in
the late '60s and early '70s. He began testing organic management methods in
'88 and quit using synthetic fertilizers
and herbicides in '90.
He's kept his farming herbicide-free since then and completely organic since
'93. He credits a flexible rotation for
part of his success. For a typical seven-year rotation he plants an
overwintering rye cover crop followed by soybeans;
a fall-planted small grain; a legume/grass mix "frost-seeded" into the grain
in late winter; several years of hay or
pasture; corn; another rye cover-soybeans sequence; cereal grain
frost-seeded with a legume/grass mix; finishing
with a fallow year when the forage mix growth is clipped but left to
replenish soil organic matter.
The seventh year's "crop" is enrichment and regeneration of soil biological
life. Erisman calculates that the soil
benefits which improve and protect succeeding crops easily offset his
opportunity cost plus clipping and $20 per acre
in taxes. A late seeding of buckwheat for grain in the seventh summer and
then a fall seeding of rye to restart the
rotation combine to provide a needed break in the legume cycle that prevents
a buildup of soil disease organisms.
To fit fields and control weeds for his broad crop mix, Erisman has an array
of cultivation equipment.
Wants Fewer Passes
Erisman's shift to organic crop production systems increases overall tillage
due to crop rotation and mechanical
cultivation. Rather than an adverse impact on the soil, he's seen changes
for the better. "Green manure crops
cushion the tillage impact," he says. "Our soil structure has improved-it's
more granular and friable than it was."
Hand digging and visual observations by researchers from the USDA National
Soil Tilth Lab showed significant
differences in soil tilth structure on his farm compared with neighboring
farms. Erisman credits the distinction partly
to his use of deep-penetrating legumes, such as alfalfa and sweetclovers,
and minimal use of deep tillage.
Erisman has fields in different stages of organic transition and many crop
sequences to juggle. Critical management
Rye to soybeans. His main rye-killing tool is a John Deere 32-foot offset
disk. In wet years, he starts with a flail
mower to stop growth and buy time until field conditions permit disking.
Final preplant weed control and soil
conditioning comes from his 36-foot field cultivator. Rye requires careful
management to coax out all its benefits.
"Rye residue can keep ground cold, and its allelopathic (weed suppressing)
effects are gone after about three
weeks," says Erisman.
Rye needs to be killed before it puts on explosive growth just before it
heads out. Rampant growth can dry out the
soil in moisture-deficient years, or present too much biomass to easily
incorporate or plant through, depending on a
farm's equipment. Mowing after flowering stage is a no-herbicide, no-till
End excerpt from Steel in the Field: A Farmer's Guide to Weed Management
Copyright 1997 by the Sustainable Agriculture Network
Andy Clark, Ph.D.
c/o AFSIC, Room 304
National Agricultural Library
10301 Baltimore Ave.
Beltsville, MD 20705-2351
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