IRRIGATING LATE SUMMER CORN USING CHANNEL CATFISH Ictalurus punctatus PRODUCTION POND WATER IN WESTERN KENTUCKY: DEMNONSTRATION PROJECT RESULTS.

Late summer corn was planted following the harvest of a winter wheat crop during late June 2014.  Irrigation water was drawn from a 1.71 ha commercial catfish pond and applied to a 13.9 ha corn field using a 247 m center pivot system equipped with a terminal spray gun.  This system was calibrated to deliver 1.5 cm of water per ha on the corn field beginning the first week of July.  Each water application was calculated as approximately 7% (2,117,443 L) of the pond water volume.   Replacement water was pumped a short distance to the irrigation pond from a nearby well.  Depending on rainfall, corn was watered about every 6 days during the eight week growing season. A nearby 1.6 ha catfish pond was used as a control.  Weekly water samples were collected from the two ponds and irrigation water suitability tests were analyzed by a commercial laboratory.

Channel catfish, Ictalurus punctatus ponds were stocked with approximately 14,800 fish per ha and were harvested and restocked in a multiple batch production scenario. Fish in both ponds were fed 84 kg/ha of 28% protein commercial catfish feed daily.  Catfish harvested were 4,672 kg for the irrigation pond and 6,539 kg for the control pond during the irrigation season.  Total fish harvested in the irrigation pond was 10,954 kg and 9,895 kg for the control pond from March through September 2014. .   Magnesium, potassium, sodium and sodium absorption ratio were statistically different (P < 0.05) in the samples taken from the irrigation and control ponds.  It is unlikely that the small differences in these water quality parameters affected catfish production.

Yellow corn was harvested during late October, 2014.   Corn production for the 13.9 ha irrigated field was 8,047 bushels with an average yield of 579 bushels per ha.  During each irrigation trip, small amounts of nitrogen (754 g), phosphorus (42 g) and potassium (1.24 kg) were delivered to the corn per ha.  Irrigation provided water essential to corn production during periods with little rainfall. However, the small amount of nutrients provided by the catfish pond water was probably of little benefit to the corn crop.