Irrigation Efficiencies, Nitrogen Applications, and Lint Yields of Upland Cotton Grown at the Marcopa Agricultural Center, 1991

The computer program AZSched, with weather data obtained from AzMet, was used to schedule irrigation for a yield trial of Upland Cotton (DPL 90) at the Maricopa Agricultural Center in 1991. Cotton lint yields were compared between plots from four treatments involving the combination of two irrigation efficiencies (70% and 90 %) and two nitrogen fertilizer applications (broadcast and sidedress). The amount of nitrogen fertilizer applied to the broadcast plots was 145# N /A. One hundred thirty pounds NIA was applied to the sidedressed plots. A potassium bromide tracer was applied to select areas in each plot at the time of initial fertilization. Soil samples from each plot were taken to a depth of 10' for analysis of bromide and nitrate to determine the depth of water movement through the soil profile. Irrigation amounts averaged 42.8" for 70% efficiency and 36.7" for 90% efficiency. No significant difference in lint yield was noticed between the two nitrogen fertilizer applications, but significant differences existed between the two irrigation efficiencies