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Rice Flooding
By Johnny Saichuk
Louisiana Extension Rice Specialist
Rayne,
Louisiana (May16, 2008) – I have had several calls
regarding rice that has been completely covered by flood waters associated
with the rain of the last few days. Some is under a couple of feet of water
and come is covered by only a few inches. While neither is good for the
crop it may not cause too great a problem. The overcast and cool conditions
are a good thing. If the water is clear that is another good thing. Once
the cloud cover breaks and it warms up conditions begin to deteriorate.
Cold water will contain much more dissolved oxygen than hot and clear water
will let some sunlight penetrate although it will probably filter out most
of the ultraviolet wave lengths. Warm muddy water is lower in oxygen and
shades the plants too much. In either case plants are likely to etiolate,
that is elongate in response to low light intensity. Affected plants can
recover if given a little TLC for a week or so post flooding.
From a management standpoint about the only thing the
farmer can do is exercise some caution in draining. If upon decreasing
water depth rice plants are laying on the water surface it is better to
leave a shallow flood on the field until new leaves or plants begin to hold
themselves upright. Weak, stretched plants if allowed to stick to the soil
surface by completely draining the field will be much more difficult to save
than those that might suffer some from the prolonged flood, but will benefit
from the support the water provides until the plants can support
themselves.
 Fields
to which herbicides have been applied could be slower to recover than those
to which little or nothing has been applied. If fertilizer has not been
applied it is better to drain the field before applying fertilizer rather
than try to “save” water costs and apply fertilizer into the flood. We did
exactly that one year in a verification field that was flooded by 11 inches
of rain over night. It was a mistake. The field stayed yellow a long time
and never completely recovered.
I hope this helps. If you have any other questions
please do not hesitate to call. I will keep my cell phone with me
throughout the weekend if you need to get in touch.
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