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

Shallow flood depth decreases the amount of water
required and increases yield if grass and weeds are controlled.
Land leveling, or grading, makes it possible to
maintain uniform, shallow flood depth; improve uniformity
of water distribution when the field is flushed; and improve
surface drainage.
Temporary shallow flooding
An adequate water supply and timely flushing (temporary
shallow flooding) are essential for maximum yields.
Early season water management is important, but often
overlooked. The planting method largely determines appropriate
early season water management practices.
Flushing encourages uniform, rapid emergence with
the broadcast, dry seeded method of planting. Flushing is
normally not used to obtain emergence when rice is drilled
into coarse textured soils because these soils are prone to
crusting, thus impeding seedling emergence.
Flushing may be necessary if there is not enough
moisture available for germination and/or if emergence is
hindered by soil crusting following a rain. Do not allow
the soil to dry or a soil crust to form on shallow planted,
semidwarf varieties.
Research indicates that much of the irrigation water
applied in flushing leaves the field as runoff. Improved
management in the flushing operation could reduce the
amount of water required and reduce irrigation pumping
costs. Introducing exactly the right amount of water to
accomplish the desired flushing with little or no runoff from
the bottom of the field is difficult with single inlet irrigation
systems.
A multiple inlet system, which introduces irrigation
water to each individual cut, makes efficient flushing much
easier to accomplish and also makes it possible to maintain
freeboard on each levee for storage of rainfall. An inflow
meter also allows you to precisely control the amount of
inflow.
Water seeded rice on heavy soils
When rice is water seeded on heavy soils, establish a
2- to 4-inch flood as soon as possible after land preparation.
The rice should be planted immediately to minimize seed
midge damage and ensure a good stand. When seed has
sprouted, drain the water to a low level or drain it completely
to enable rice seedlings to become well anchored.
If cuts (the areas between levees) are completely drained,
flushing will eventually be necessary to prevent soils from
drying out and reducing seedling stand. Floods that last longer
than 7 to 10 days may lead to seed midge damage.
Early season water management
Early season water management should provide soil
moisture for growth of the rice seedlings, discourage germination
of weed seeds and maintain high nitrogen fertilizer
efficiency. Young rice plants grow well under alternating
moist and dry soil conditions, but denitrification can seriously
reduce the soil’s nitrogen level under these conditions.
If possible, keep the soil moist to increase nitrogen
efficiency, decrease germination of weed seed and reduce
salt damage in areas subject to such damage. Keeping the
soil moist appears to be especially important for semidwarf
varieties.
Delay flushing until 24 hours after propanil is applied
(alone or in combination with a preemergence herbicide).
Flushing immediately after propanil application washes off
the propanil.
Flood Establishment
Do not put on flood until plants are actively tillering,
assuming continuous flood culture is not being used. To
maintain the flood, apply additional water to replace that
lost by evaporation, transpiration, seepage and runoff.
The flood may be drained during mid-season only when
the rice is subject to straighthead. If you need to apply a
mid-season herbicide, lower the flood level to obtain better
exposure of broadleaved weeds. To ensure availability
of water during the reproductive stage, the rice must be
reflooded at least 7 to 10 days before anticipated panicle
differentiation.
Maintaining a flood is critical during panicle development.
The rice plant uses water at a high rate during
this period, and moisture stress reduces yield. Maintain a
constant flood to provide adequate water for normal plant
growth and development.
Maintain the flood at the minimum depth necessary to
control weeds. Shallow flood depth minimizes the quantity
of water required and increases yield if weeds are controlled.
Field storage of rainfall can also reduce the amount of
irrigation water required. However, rainfall can be stored in
the field only if some freeboard is available on each levee
gate.
Fertilization
L. Tarpley and M. F. Jund
Research and experience have shown that there is a great
deal of flexibility in how farmers can manage their fertilizer
programs, provided that the basic nutrient requirements are
met. These suggestions provide basic information on which
a farmer can build an economic rice fertilizer program and
make adjustments to fit particular situations.
Fertilizer can profoundly influence rice yield, and it is a
major cost for rice production. Therefore, a critical review
of fertilizer practices can mean increased income without
sacrificing yields.
For maximum net profit, apply only those fertilizer
materials needed for maximum economic yields. If your soil
has been tested accurately to predict fertilizer needs, you
can have confidence in the fertilizer recommendations and it
will help you develop an economical fertilizer management
program.
Of the three primary nutrients (nitrogen, phosphorus
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