Hi I'm Erin Silva, associate professor and state extension specialist in organic agriculture at the
University Wisconsin Madison. Hi I'm Daniel Smith, southwest regional agronomist for the nutrient
pest management program at the University of Wisconsin-Madison. Erin, it's getting about time
to interseed cover crops into corn. What are some things that you've learned in your organic cover
crop interseeding work? It is time where farmers are considering interseeding cover crops into
their organic corn crops, and there's multiple reasons why organic farmers might consider this.
Cover crops can help suppress weeds and offer an additional weed management tool. Cover crops
can help build soil health, and potentially cover crops could add an option for grazing
after the corn is harvested. So organic farmers have multiple goals that they might consider
when thinking about interseeding cover crops and what species they might want to select.
We've been working with interseeding cover crops for about the last five years now. When we started
this work, we took recommendations primarily from the east coast in terms of what species to plant
and when to plant those cover crops. We found that there is some adaptation needed as we
bring interseeding cover crops into Wisconsin, into our cropping systems and into our climate.
So what are some things that farmers should consider if they're going to be interseeding this
year? One of the things that we've found, is that potentially interseeding cover crops
a little bit earlier than what is the typical recommendation can be beneficial. Oftentimes we
see recommendations where interseeding cover crops occurs around the V5 stage of corn.
And what we found in Wisconsin is that if we interseede in that stage, it's a bit too late.
We see what we call a disappearing cover crop phenomenon, where those cover crops might emerge
but by the end of the season they have not really established and the growth is minimal.
So what we've been experimenting with in our plots here at Arlington is pushing that seeding
date a bit earlier. So instead of waiting till the V5 stage, we've been interseeding cover
crops around the V3 stage of corn, which takes a little bit of adaptation with respect to our
weed management strategies in that organic corn crop. What are some of those strategies Erin,
to manage the weeds and also establish cover crop in organic systems? It's definitely a balance!
So when we're thinking about interseeding cover crops and having as clean of a field as possible,
one of the things we consider is starting off clean. So we don't want to interseed cover crops
into a field where there's already existing weed pressure, particularly with perennial weeds. So we
want to go into a field where we know the history, we know the source of weed species, and we know
that there's not excessive weed pressure. The second thing a farmer might consider is planting
a little bit later. Typically with organic corn we're planting later anyway, often times not until
the third week of May. And planting later allows us to do a technique we call "false seed bedding",
where the weeds will already emerge and then we're able to go through and do a field cultivation pass
to knock back those weeds and do some depletion of the weed seed bank. And then the third thing
a farmer has to adapt is their cultivation. So if we're planting around the V3 we're really relying
on a lot of our blind cultivation techniques, tine weeding and rotary hoeing. So we want to be
as efficient and ineffective with those blind weeding techniques to knock back weed populations.
Because if we're planting at the V3 stage, we're likely then skipping a row cultivation.
So getting really diligent initial weed management is critical with with respect to interseeding,
and coming in at those early stages we're going to be more apt to get a good cover crop stand.
Great. Where can producers learn more information? You can go to our website Ograin,
if you google "Ograin University Wisconsin Madison" you'll see the url,
and we have more information there-- videos and fact sheets. Perfect, thanks Erin.
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