Success with Organic Grains: Seedbed Preparation


[ background music ] Success with Organic Grains: Seedbed Preparation>>Narrator: Produced by
University of Georgia Extension, North Carolina Extension, and the United States
Agricultural Research Service in Tifton, GA and
Beltsville, MD. With funding by Southern Sustainable Agriculture
Research and Education program. Agronomists often say that
your highest yield potential is the day the seed
goes in the ground. There are many things
a farmer can’t control over the growing season,
but getting your crop started off right with
a good seedbed is one thing you can do to
maximize yields. Although each farm may take
slightly different approaches depending on the equipment
available, soils, and weather, there are key things
to strive for when preparing a good
seedbed for planting.>>Mr. Carroll Johnson:
Conditions of influence, crop stand, and uniformity
of crop stand are essential in order to achieve maximum
crop yield potential. This can be achieved by simply
striving for good soil-seed contact which is a
function of soil tilth, equipment configuration, and
the overall sum total of what the seedbed
preparation practices are. One of the real benefits–
understated benefits– of uniform crop stand is the fact that’s a
form of cultural weed control. The crop is ahead of the weeds. When this is the case,
every subsequent weed control practice stands to be
success which is essential in organic crop production.>>Narrator: Tillage may
be necessary to prepare good seedbeds and
to manage weeds. This is particularly true with
crops like wheat and canola. It may also be true for
corn and soybeans if the cover crop has
not produced enough biomass to suppress weeds
to use a no-till system. Cover crops are an essential
part of organic production. They improve the soil organic
matter, reduce erosion, suppress weeds, and in the case
of legumes, provide nitrogen. Unless you’re using
a heavy residue cover crop in a no-till system,
your cover crop needs to be tilled in before
planting your cash crop. This process needs to start a
month before planting to make sure the cover crop has
time to properly decompose. If you plant before the
cover crop is decomposed, you can have higher stand
losses due to disease, poor seed-soil contact
and other issues. Timing can be tricky. Of course, you don’t want
to have equipment in the field when the
soil is too wet. So you will need to plan ahead
and look for dry weather. Cover crops can be
incorporated directly or mowed. If you have a large amount
of cover crop biomass, let’s say cover crops
taller than 2 to 3 feet, mowing the cover crop before
it is incorporated will make it easier to incorporate and
help speed its decomposition. You can use a rotary mower,
but rotary mowers tend to throw all the cover crop to one
side and leave it in clumps. Many growers also use a flail
mower that tends to leave a more even distribution of
cover crop over the ground. Incorporating cover crop
is part of the primary
tillage operation. Tillage needs to be
performed when the soils
are not too wet or too dry. Test your soils moisture
conditions by taking a handful of soils and
squeezing it into a ball. If your soil ball breaks
under gentle pressure or when you drop it on the ground,
it is not too wet to till. If it is totally dry
and shatters to dust, it is too dry to till. Tilling when the soil
is too wet or too dry destroys soil structure. Tilling when the soil is too wet
also creates soil compaction. Moldboard or switch plows,
chisel plows, and heavy disc
harrows can be used. Each has its own advantages
and disadvantages. Moldboard and switch plows
completely turn the soil over burying the cover crop and any
weed seeds on the soil surface. Although this can
be an advantage, it also presents
some disadvantages. This is most aggressive
tillage and accelerates the decomposition of
soil organic matter. Soils in the Southeast
naturally have fairly low soil organic matter
due to the hot humid conditions that
generally prevail. Tillage breaks down soil
structure and adds oxygen, creating a burst of growth
from soil microorganisms which decompose
the organic matter. The carbon that is the primary
building block of soil organic matter is lost to the atmosphere
as carbon dioxide. Because building and maintaining
soil organic matter is critical for organic production systems,
tillage should always be used wisely and reduced
when possible. Many farmers use chisel
plows for primary tillage. These tend not work as well
for incorporating cover crops. Chisel plows work best for
breaking up compaction layers in the soils without
completely inverting the soil. A heavy tandem disc harrow does
a good job with cover crops. It partially chops and
then buries the cover crop, but does not totally
invert the soil. The disadvantage here is that
multiple passes will need to be made to incorporate residue
and surface weed seeds can be left on the surface
to germinate. Many farmers use a
combination of tillage. They might use a disc
harrow for a first pass, then a switch plow. Other may make several
passes over the field with a disc harrow. Once primary the cover crop
is incorporated with primary tillage, a good seedbed
still needs to be prepared. In general, at least two tillage
operations will need to be performed to break up clods, further incorporate cover
crop residue and kill weeds. A light harrow or
a field cultivator is a good choice for
seedbed preparation. The goal at this stage is
preparing the soil surface so shallower tillage with less
soil disturbance is the goal. Use the lightest implement
possible for the soil conditions. The second pass should be
4 days to 1 week after
the first primary tillage. This allows weed seeds to begin
to germinate, but kills them in the thread stage before they are
able to establish themselves. Thread stage weeds
are very small. So shallow tillage
should be done BEFORE you can
really see the weeds. Once you can see them,
shallow tillage doesn’t work. Shallow tillage also won’t
work with perennial weeds. If possible, till in the
morning of a sunny day. This should leave the tiny
weeds on the soil surface exposed to the
sun to dry out. You may need to conduct
a third tillage pass about 1 week after the second
to continue weed management and to continue
preparing the soil. If some of the cover crop
residue on or near the surface or there are still clods,
another pass with the harrow or field
cultivator will help. If the soil surface
looks relatively clean, a tine weeder or similar tillage
tool is a better option. The tine weeder will kill small
weeds at the thread stage and help create a weed free soil
surface as long as you don’t bring up new weed seeds
by deeper tillage. It will also help preserve
soil organic matter by minimizing the amount of
soil disturbed while still creating a friable
soil surface. Depending on conditions, you may make several passes
with the tine weeder. Making these passes at right
angles to each other helps ensure all the ground
is well covered and as many weeds as
possible are killed. And remember,
don’t wait! Get those weeds
before you see them. You should make a
final pass with the tine weeder or
lightest tillage tool. Ideally, this is
the day of planting. Making this final pass
as close as possible to planting will give you crop
a head start on weeds and contribute to
ultimate success. This is particularly important
for crops like wheat or canola. With drilled wheat, the narrow
rows preclude any further weed management, so you need to
get it right at planting. For crops like corn,
soybeans and sunflowers, you’ll have one more opportunity
with a blind cultivation. A good seedbed gets you
off to the right start with the capacity to
get good seed-soil contact and a good stand. Proper seedbed preparation
also helps you get ahead of the weeds so they don’t
get ahead of you! Remember: Plan ahead and incorporate
your cover crop at least one month before planting; Only work the soil under
right moisture conditions; Use the lightest tillage
option possible to get the cover crop incorporated
and the bed prepared with minimal
soil disturbance; Plan on making several
passes to kill germinating weeds
in the thread stage; Do a light cultivation as
close to planting as possible; If the crop will allow,
try a blind cultivation after planting to help
control in-row weeds. Now that that we’ve
discussed some good seedbed preparation practices,
be sure to download “Steel in the Field – A Farmer’s
Guide to Weed Management Tools” from the SARE Learning Center at
the address listed on the screen. For additional questions
specific to your area, contact your local
Extension office. Find your local Extension
office by using the address
listed on the screen. [ background music ] Captioning provided by:
2014 University of Georgia
College of Agricultural and
Environmental Sciences
UGA Extension
Crop & Soil Sciences Dept.

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