Cool weather helping harvests

By Eddie Eskew
AgCenter County Agent

The weather in the last couple of weeks has been just beautiful. The cool, dry conditions have made it enjoyable to be outside and has been excellent for soybean harvest, second crop rice harvest, and out last hay harvest.
This weather has also been favorable for crawfish production, as cool weather means cool water, which means good oxygen. With fuel prices still high, it is to your advantage as a crawfish farmer to have cool weather as flood up begins so that you don’t have to exchange too much water.
The October flooding recommendation takes into consideration not only peak crawfish spawning periods, but, just as important, water quality, specifically dissolved oxygen management and the ability and willingness of farmers to manage water quality. Because vegetation type and quantity affects water quality, your forage crop must also be taken into consideration when deciding on an appropriate flooding date.
If rice was planted in the pond for crawfish forage, a shallow, partial flood of several inches in September is sufficient to keep the rice growing, and this shallow flood will not flush out females prematurely that are burrowed above water line. By early October when the daily temperature begins to cool a bit, and the rice is 18 inches or taller, the water level can be raised by 12 to 15 inches (or near full flood) to assist in flushing females with young from their burrows.
Consider flooding to a depth three to four inches below the top of the drain pipes and allow late autumn and early winter rains bring raise the water level gradually to full flood.
Flushing is required only to correct an oxygen deficiency. Because of high pumping costs, water management decisions should be based on oxygen measurements. No benefit to crawfish health and survival is gained by exchanging water if oxygen levels are satisfactory.
Although pond water lacking in oxygen is often clear and dark (the color of tea, coffee or cola) one should not rely on visual observation or smell to determine oxygen concentration. Dissolved oxygen can be measured with a meter or chemical test kit. A dissolved oxygen meter is best if you have many ponds to check. Most producers, however, choose oxygen test kits because the kits are inexpensive and easy to use.
The easiest kit uses a vacuum ampoule that draws in a water sample. The oxygen concentration is determined by matching the color of the sample in the ampoule to a chart. A list of supplier of test kits and meters with advantages and disadvantages of each is available in the publication “Measuring Oxygen in Crawfish Ponds,” available on the LSU AgCenter crawfish web page.
Ideally, dissolved oxygen should be maintained above two parts per million (ppm) for good crawfish production.