Dear
Jeff,
How can I manage weeds in a no-till farming system without
herbicides?
Carlos Brigard
Colombia
Dear Carlos,
Thanks for the question on weeds in no-till and for reading
New Farm. The question you ask is really the most important
one of all and gets to the heart of why we till the soil in
the first place. We till the soil for two main reasons: first,
to get good seed-to-soil contact; second, to help us manage
competition from weeds.
As conventional ag has moved in the direction of reduced
tillage, it has increased its reliance on herbicides to help
manage weed pressure. As organic farmers consider reducing
or eliminating tillage from their system, they need to think
about increasing their use and management of cover crops.
These cover crops will really be the key to the success or
failure of the no-till system.
In order to be successful, you'll need to select cover crops
that match up in timing with your cash crops. An example of
this would be using a legume like hairy vetch as a cover crop
to plant corn into. As the vetch matures and flowers in late
spring, it can be killed mechanically with a
tool like the one we designed here at The Rodale Institute,
and the corn can be planted directly into the rolled mat of
vetch. In this example the vetch needs to be planted the fall
before the corn, it needs to be a thick stand, and it needs
to be established with the same care you would expect to give
any cash crop. This cover crop will then supply all the nitrogen
for the corn and suppress the weeds through a smothering and
mulching effect.
Weeds are very opportunistic. They will not grow when a dense
stand of an established crop is in place. They are also generally
small-seeded, need access to light to stimulate their germination
and will have trouble breaking through the thick mat of the
rolled cover crop. Keep in mind that any place in the field
where bare soil is exposed, weeds will germinate and break
through the protective layer of mulch.
You can read much more about this on our No-Till
Plus page or in our no-till
forum section. Also checkout the FAQ
section to get more insight into how this system works.
Jeff
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