• Evaluation of a Feedback Approach to Nitrogen and Pix Application

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      A single field experiment was conducted in 1995 at Maricopa, AZ to compare a scheduled approach (based on stage of growth) versus a feedback approach (based on vegetative status) to both nitrogen (N) and mepiquat chloride (PIX™) applications on Upland cotton (Gossypium hirsutum L.). PIX feedback treatments were based upon fruit retention (FR) levels and height to node ratios (HNRs) according to established baselines. Scheduled and feedback PIX applications were made for a total of 1.0 pt./acre over two applications, with the scheduled treatments-taking place earlier in the fruiting cycle (early and peak bloom). Feedback PIX treatments began with a single 0.5 pt. /acre application near peak bloom (approx. 2200 heat units after planting (HUAP), 86/55 °F threshold) and followed with a second 0.5 pt. /acre application in late bloom. Scheduled applications of fertilizer N totaled 200 lbs. N/acre from three applications and feedback N treatments received a total of 100 lbs. N/acre from two applications. Treatments consisted of all combinations of scheduled or feedback applications of both N and FIX. The highest lint yields were from a treatment receiving feedback N and FIX, but all treatment yields were not significantly different (P ≥ 0.05) from one another. From a practical (economic) standpoint, however, these treatments were different in terms of the differences of fertilizer N and the timing of the PIX applications required to produce comparable yields. Results from 1995 are consistent with 1993 and 1994 results from the same study.
    • Evaluation of Soil Conditioners and Water Treatments for Cotton Production Systems

      Silvertooth, J. C.; Sanchez, C. A.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Advanced technologies to produce synthetic polymers such as polyacrylamide (PAM, and polymaleic anhydride (PMA) have produced products which may be economically feasible alternatives to traditional treatments such as gypsum in the desert Southwest. In 1995 a single field study was conducted at Paloma Ranch, west of Gila Bend in Maricopa County Arizona Upland Nucoton 35, DPL' was dry planted and watered -up on 10 and 11 April. Treatments consisted of various rates and times of applications of Sper Sal™, which included a check (no Sper Sal), 1 and 2 qts. /acre with the water-up irrigation; 1 and 2 qts./acre with a mid - season irrigation; and 1 qt. /acre mid-season following 1 or 2 qts./acre with the water -up irrigation. No differences among treatments were detected among any treatments in terms of plant growth and development or final lint yields. There were no early-season differences in soil crusting among the various soil amendment treatments in 1995, as opposed to 1994 when a severe rain occurred immediately following planting.
    • Nitrogen Management Experiments for Upland and Pima Cotton, 1995

      Silvertooth, J. C.; Norton, E. R.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Three field experiments were conducted in Arizona in 1995 at three locations (Maricopa, Marana, and Safford). The Maricopa and Safford experiments have been conducted for seven consecutive seasons, the Marana site was initiated in 1994. The purposes of the experiments were to validate and refine nitrogen (N) fertilization recommendations for both Upland and Pima cotton. The experiments each utilized N management tools such as pre -season soil tests for NO₃⁻-N, in- season plant tissue testing (petioles) for N fertility status, and crop monitoring to ascertain crop fruiting patterns and crop N needs. At each location, treatments varied from a conservative to a more aggressive approach of N management. Results at each location revealed a strong relationship between the crop fruit retention levels and N needs for the crop. This pattern was further reflected in final yield analysis as a response to the N fertilization regimes used. The higher, more aggressive, N application regimes did not benefit yields at any location. The effects of N fertility levels have also been consistently evident in crop maturity and its relationship to lint yields.
    • Potassium Fertilization of Pima and Upland Cotton at Three Arizona Locations

      Galadima, A.; Silvertooth, J. C.; Norton, E. R.; Husman, S. H.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Three field trials were conducted in Arizona in 1995 at three locations (Safford, Maricopa and Buckeye) to evaluate yield benefits associated with potassium (K) fertilization. The 1995 and previous years studies were aimed at assessing the agronomic necessity of K fertilization in Arizona cotton (Gossvpium spp.) production. At the Safford Agriculture center (Pima clay loam), both Upland (G hirsutum L., var. DPL 90) and Pima (G. barbadense L., var. S-7) cotton included treatments of both soil and foliar K applications. The trial at Maricopa Agricultural Center (Casa Grande sandy loam) included four foliar K applications over the growing season on Pima (G barbadense L., var. S-7) cotton. The third trial was at the Buckeye location (Superstition silty loam) where a single foliar application over split plots preceded by soil application on Pima (G. barbadense L, var. S-7) cotton was undertaken. The results of the experiments at the Safford and Maricopa locations indicated no lint yield responses to K fertilization by either Upland or Pima cotton; however, at the Buckeye location, the result indicated a significant difference between the means of the soil-only and the soil-plus-foliar treatments. There were however no significant differences among soil-only treatments as well as the soil-plus-foliar treated plots when compared to their respective controls.
    • Reduced Tillage Systems for Airzona Cotton Growers

      Coates, Wayne E.; Thacker, Gary W.; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Four alternative tillage systems were compared to a conventional system at The University of Arizona Agricultural Centers in Marana and Yuma. The alternative tillage systems offer significant savings in energy, time, and cost. None of the reduced tillage systems were associated with a reduction in cotton yield.
    • Tillage Energy Savings from Zone Burial of Shredded and Whole Cotton Stalks

      Carter, Lyle; Chesson, Joe; Thacker, Gary; Penner, Vic; Silvertooth, Jeff (College of Agriculture, University of Arizona (Tucson, AZ), 1996-03)
      Two prototypes of a stalk burial implement were tested for energy requirements at the University of California, Shaffer Research Station. Both versions of the implement are designed to bury the cotton stalks in a concentrated zone and reform the bed in the same location. To plow under shredded stalks, both versions of the implement required less energy than a conventional tillage systems typical of the San Joaquin Valley of California. Both stalk burial implements were also used to plow under whole cotton stalks. This offers additional energy savings by eliminating the stalk shredding operation.