• Comparison of Three Irrigation Scheduling Methods and Evaluation of Irrigation Leaching Characteristics

      Scherer, T.; Slack, D.; Watson, J.; Fox, F.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Three methods were used to schedule irrigations on replicated plots at the Maricopa Ag Center using DPL 90 cotton. The three methods were: a soil water balance model based on historic consumptive use curves, a soil water balance model based on the Modified Penman Equation and daily weather (AZMET), and infrared thermometry using the C.W.S.I. A potassium-bromide conservative tracer was applied at selected sites in the plots to evaluate leaching characteristics. The irrigation scheduling test was duplicated at the Safford Experiment Station and is presented in another report. Results from the 1988 data indicate that there was no significant difference in yield between the 3 methods. There was a significant difference in water applied; the historic consumptive-use curves was the lowest and the Penman equation method was the highest.
    • Cotton Irrigation Scheduling, Safford Agricultural Center, 1988

      Clark, L. J.; Carpenter, E. W.; Scherer, T.; Slack, D.; Fox, F.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Cotton was grown using historical evapotranspiration data in the Erie method a checkbook method using real-time AZMET weather data, an infrared thermometer, and a faint manager to schedule irrigations. Yields of 4 bales per acre were recorded with no significant differences between the scheduling methods. Differences were seen in the plant growth and maturity. More refining will be done in subsequent investigations.
    • Irrigation Frequency During Fruiting as a Yield Determinant in Upland Cotton

      Radin, J. W.; Mauney, J. R.; French, O. F.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      When cotton is irrigated at long intervals, the root systems become less effective at absorbing water during heavy fruiting, even when the soil is moist. That ineffectiveness, if not counteracted by frequent watering can exaggerate water stress responses during fruiting and promote early cutout. Deltapine 90 cotton was grown at the Maricopa Agricultural Center in 1988 and watered either by daily drip irrigation or by level -basin flooding. In the flood-irrigated plots, various schedules for applying water during fruiting were compared with minimal differences in total water applied. The check treatment (9 postplant irrigations) yielded approximately 2 bales of lint per acre. Small supplemental irrigations on 13 July and 22 July, splitting the normal irrigation cycles, increased yield 45% for only 6% more applied water. Daily drip irrigation in the trials increased yield 63% above the check on 1% more applied water over the season. The results show that flood- irrigated yields can approach drip-irrigated yields without excessive water use, if the irrigation cycle is shortened during fruiting.
    • On Farm Cotton Irrigation Scheduling Management Using Infrared Thermometers in Arizona

      Garrot, D. J. Jr.; Fangmeier, D. D.; Husman, S. H.; Stedman, S.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
    • Scheduling Pima Cotton Irrigations Using Infrared Thermometers

      Garrot, D. J. Jr.; Fangmeier, D. D.; Husman, S. H.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)
      Plots of pima S-6 cotton were scheduled for irrigation using the Crop Water Stress Index (CWSI). Irrigations were applied when CWSI levels reached 0.08 (wet), 0.34 (medium), and 0.68 (dry) units. The medium treatment had significantly higher lint yield. Preliminary test results indicate the CWSI can be useful in irrigation-management decisions regarding pima cotton production.
    • Tierra Prospera Farms CWSI Irrigation Scheduling Demonstration Test

      Garrot, D. J. Jr.; Stedman, S.; Benedict, D. B.; Silvertooth, Jeff; Isbell, Joan (College of Agriculture, University of Arizona (Tucson, AZ), 1989-03)