2007 - Texas A&M AgriLIFE Research Center at Beaumont - Texas ...

Land and Seedbed
Preparation
G. N. McCauley
Leveling and drainage considerations
Fields for growing rice should be relatively level
but gently sloping toward drainage ditches. Ideally, land
leveling for a uniform grade of 0.2 percent slope or less
provides:
• Necessary early drainage in the spring for early soil
preparation, which permits early seeding;
• Uniform flood depth, which reduces the amount of
water needed for irrigation; and
• The need for fewer levees.
Importance of early land preparation
Successful rice production requires timely land preparation.
Therefore, fields should be plowed in the summer
or early fall. Early land preparation is particularly critical
when high-residue crops such as grain sorghum or corn
are planted the year before rice. If the land has been out of
production and is grown up in weeds and brush, prepare it
as early as possible.
Early land preparation allows several stands of grass and
red rice to be killed by surface cultivation before planting.
It also incorporates the crop residue to assure good decomposition
of plant material to prevent early-season nitrogen
deficiency.
If it is not possible to prepare the land early, plant
material decomposition will not be at advanced stages at the
time of planting. The soil’s microorganisms (bacteria, fungi,
etc.) that decompose crop residue will compete with rice
plants for nutrients, particularly nitrogen, causing the rice
plant to be nitrogen deficient. If this situation arises, you
may need to add 10 to 20 more units of nitrogen when the
base fertilizer is applied at or near planting.
Land preparation for rice
after soybean production
Less land preparation is needed when rice is planted
after soybeans because the soil is normally left in fairly good
condition. In water-seeded areas where the land is weed-free
and firm, it may even be feasible to plant rice after reduced
tillage (one or two cultivations) of the crop land.
Seedbed preparation
Seedbed preparation is particularly critical in coarse-textured
soils. The seedbed should be firm and well pulverized
to maintain proper moisture conditions for drilling. This
will ensure rapid germination and emergence of the rice
plant.
Although seedbed preparation is less critical in areas
where rice is not drilled, it is still important to ensure that
the desired soil condition is achieved and to allow rapid
emergence of the rice plant. In all situations it is important
to have a weed-free seedbed.
To reduce costs, minimize the number of times a field
is cultivated before planting. Avoid “recreational” passes
over the field. Research has shown that fields cultivated five
times have about the same average yields as those more
intensely cultivated.
The cost of operating large tractors for rice production
means that one cultivation can cost up to $5 per acre.
Therefore, some farmers are adding as much as $30 per acre
to the cost of land preparation and may not be realizing a
corresponding yield increase.
Reduced tillage
Reduced tillage refers to any effort to reduce the number
of land-preparation trips across a field. The discussion here
will be restricted to spring and fall stale seedbed techniques.
Spring stale seedbed provides less reduction in cultivation
than does the fall stale seedbed technique. The spring
system involves normal fall land preparation with early
spring seedbed preparation. The seedbed is allowed to set
and weeds germinate. The weeds are controlled chemically
right up to planting. With the spring system, the rice can be
drill- or water-seeded. For satisfactory stand establishment,
you must use a minimum- or no-till drill.
The major benefit of the spring system is the management
of red rice. For more details on the spring stale seedbed
technique, see the section on Red Rice Control.
The fall stale seedbed technique entails cultivation and
seedbed preparation in late summer or early fall. Vegetation
is chemically controlled through the fall, winter and
spring up to planting. The last burn-down application can
be applied with a preplant herbicide application just before
planting.
The major advantage of fall stale seedbed is that it
ensures optimum early planting, particularly in a wet year
when conventional spring field preparation is delayed
because of wet field conditions. Equipment and labor costs
can be reduced because fields are not cultivated as often
with reduced tillage; however, using burn-down herbicides
can increase the total herbicide cost.
In a conventional cultivation system, the condition of the
seedbed is often unknown until planting. This may make it
difficult to select seed rate and to plant. With the fall stale
seedbed technique when vegetation is managed properly,
the seedbed condition is known for weeks or months before
planting. Seeding rate selection and seed booking can be
completed well before planting.
In a fall stale seedbed system, the seeding rate can generally
be reduced 10 to 20 percent when drilling to moisture.
Use a higher seeding rate if a germination flush will be
required. This is critical if a preplant herbicide is used.
Planting methods are limited to drill- or water-seeding
because broadcast seeding requires tillage equipment for
seed incorporation. Because the use of a minimum- or
no-till drill is essential, it may be necessary to invest in
additional equipment. There is also the potential for extra
herbicide use.
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