Please share your cover
crop experiences with all of us.
What are your experiences with cover crops?
Which ones provide good biomass in your soils?
What system do you use to calculate the nitrogen return or
credit?
Here are some experiences from Mary Howard
and Klaus Martin (great diverse sustainable farmers in NY) (From SANET-MG
listserv)
I
have used red clover as my main nitrogen source for many years. When I first
converted to organic, clover grew rampantly producing more than 400#/acre of N
on the best fields including the growth that took place in the wheat or spelt
crops that the clover had been seeded into. As soil nitrogen increased, the
growth of clover has slowed until now we get between 50# and 100# in the fall
and up to 150# in the spring depending on when it is plowed. Not all of this
nitrogen is from recent fixation. Legumes respond to high levels of soil
nitrogen by fixing less new nitrogen. I think much of the spring growth may
have reused nitrogen that had been fixed in the previous fall and incorporated
into the new spring growth.
Our
challenge in the Northeast is to get the nitrogen to mineralize at the time the
crop needs it. We have had so much cold wet weather in May and early June of
the past 7 years that nitrogen is not mineralized fast enough to meet the needs
of both the crop and the residue breakdown until the soil becomes warmer. I
used a small amount of Chilean nitrate last year (12#
N/acre)
in the starter to help the early corn and it seemed to make a big difference.
Yields were up to 40 bushels per acre higher where I used the extra N. If your
P index allows it or where it is low enough so that extra P is needed, manure
could also supply part of your N requirement. Be careful if you use layer
manure. It contains a large amount of calcium and lime must be reduced to
account for that.
The
big challenge with organic N is timing mineralization to coincide with crop
demand. If N is very deficient, grow crop that needs less and wait until you
have enough to produce corn unless you have a lot of cheap manure.
>
Date: Tue, 30 Jan 2007 17:16:32 +0000
>
From: craig mcsparran <[log in to unmask]>
>
Subject: clover nitrogen contributions to corn
>
>
<html><div style='background-color:'><P> </P>
>
<P>Sanet</P>
>
<P>I have a question regarding the amount of nitrogen that can be
>
contributed from a winter annual crimson clover, grown prior to corn.
>
I believe a standard contribution would be between 50-100#
>
of nitrogen from a good stand of crimson clover plowed down prior to
planting corn in the mid-Atlantic area.
>
However if the clover was chopped for forage and only the root mass of
>
the clover was left, would a substantial amount of the nitrogen still
>
be available for the following crop or was most of the available
>
nitrogen removed in the above ground biomass?</P> <P>If anybody has
>
had experience using Chilean nitrate as a supplemental source of N for
>
organic corn I would like to hear your thoughts on this practice.</P>
>
<P>Craig McSparran</P>
Vicki Morrone
Organic Vegetable and Crop Outreach Specialist
Michigan State University
C.S. Mott Sustainable Food Systems
303 Natural Resources Bldg.
East Lansing, MI 48824
517-353-3542
517-282-3557 (cell)
517-353-3834 (fax)
http://safs.msu.edu/
http://www.mottgroup.msu.edu/
