Managing Cover Crops Profitably - Valley Crops Home
Managing Cover Crops Profitably - Valley Crops Home
Managing Cover Crops Profitably - Valley Crops Home
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eplace the cover crop before beans, in a threecrop,<br />
two-year rotation (corn>wheat>doublecrop<br />
beans). In all cases, another legume or a<br />
grass/legume mixture can be used instead of a single<br />
species cover crop. Where it is adapted, you<br />
can use crimson clover or a crimson/grass mixture<br />
instead of vetch.<br />
In cooler areas, plant rye as soon as possible<br />
after corn harvest. If you need more time in the<br />
fall, try overseeding in rowed beans at drydown<br />
“yellow leaf”stage in early fall, or in early summer<br />
at the last cultivation of corn. Seeding options<br />
include aerial application where the service is<br />
economical, using a specialty high-body tractor<br />
with narrow tires,or attaching a broadcast seeder,<br />
air seeder or seed boxes to a<br />
cultivator.<br />
Kill the rye once it is about<br />
knee-high, or let it go a bit<br />
longer, killing it a couple of<br />
weeks before planting beans.<br />
Killing the rye with herbicides<br />
and no-tilling beans in narrow rows allows<br />
more time for cover crop growth, since you don’t<br />
have to work the ground. If soil moisture is low,<br />
consider killing the rye earlier. Follow the beans<br />
with hairy vetch or a vetch/small grain mixture.<br />
Legumes must be seeded at least 6 weeks before<br />
hard frost to ensure winter survival. Seed by<br />
drilling after soybean harvest, or by overseeding<br />
before leaf drop. Allow the vetch (or mixture) to<br />
grow as long as possible in spring for maximum N<br />
fixation.<br />
Worried about planting your corn a bit<br />
late because you’re waiting for your cover crop to<br />
mature Research in Maryland, Illinois and elsewhere<br />
suggests that planting corn towards the<br />
end of the usual window when using a legume<br />
cover crop has its rewards. The delay can result<br />
in greater yields than earlier planting, due to<br />
greater moisture conservation and more N produced<br />
by the cover crop, or due to the timing of<br />
summer drought (62, 64, 243, 338). Check your<br />
state variety trial data for a shorter season corn<br />
hybrid that yields nearly as well as slightly longer<br />
season corn.The cover crop benefit should overcome<br />
many yield differences.<br />
Growers are looking to add<br />
a small grain to their<br />
corn>soybean rotation.<br />
Worried about soil moisture There’s no<br />
question that growing cover crops may consume<br />
soil moisture needed by the next crop. In humid<br />
regions, this is a problem only in an unusually dry<br />
spring.Time permitting, allow 2 to 3 weeks after<br />
killing the cover crop to alleviate this problem.<br />
While spring rainfall may compensate for the<br />
moisture demand of most cover crops by normal<br />
planting dates, rye can quickly dry out a field.<br />
Later in the season, killed cover crop residues<br />
in minimum tillage systems can conserve<br />
moisture and increase yields.<br />
In dryland areas of the Southern Great Plains,<br />
lack of water limits cover crop use. (See Dryland<br />
Cereal Cropping Systems, p. 40).<br />
In any system where you<br />
are using accumulated soil<br />
moisture to grow your cash<br />
crop, you need to be extra<br />
careful. However, as noted in<br />
this section and elsewhere<br />
in the book, farmers and<br />
researchers are finding that water-thrifty cover<br />
crops may be able to replace even a fallow year<br />
without adversely affecting the cash crop.<br />
Corn>Rye>Soybeans>Small Grain>Hairy<br />
Vetch. This rotation is similar to the<br />
corn>rye>soybeans rotation described above,<br />
except you add a year of small grains following<br />
the beans. This is the standard rotation in the<br />
grain-growing regions of Paraguay and Brazil,<br />
where it is critical to maintain soil organic matter.<br />
In crop rotation research from different areas,<br />
many benefits accrue as the rotation becomes<br />
longer. This is because weed, disease and insect<br />
pest problems generally decrease with an<br />
increase in years between repeat plantings of the<br />
same crop.<br />
Residue from small grains provides good organic<br />
matter for soil building, and in the case of winter<br />
grains, the plants help to prevent erosion over<br />
winter after soybeans loosen up the soil. If seeding<br />
with small grains, select cover crops that will<br />
stand shade and some traffic.<br />
The length of the growing season will determine<br />
how you fit in cover crops after full-season<br />
CROP ROTATION WITH COVER CROPS 35
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