• Nitrate Leaching Potential from a Single Border-Flood Irrigation

      Ottman, M. J.; Watson, J. E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Groundwater contamination by nitrate and other chemicals is a public concern and has subjected agriculture to scrutiny. Field studies were conducted at the Maricopa and Marana Agricultural Centers in 1989 to 1990 to document nitrate leaching potential with border flood irrigation. Calcium nitrate fertilizer was applied at various rates along with potassium bromide, which serves as an additional indicator of nitrate movement. Approximately 8.55 inches of irrigation water was applied at the Maricopa site on a sandy loam soil and 4.0 inches of irrigation water was applied at the Marana site on a clay loam soil. At the Maricopa site, only 64% of the nitrate could be accounted for in the top 6.7 ft. while most of the nitrate was found in the top 4 to 5 ft. at Marana. The water and nitrate moved 3 to 4 times deeper than predicted in the absence of preferential flow.
    • Grain Sorghum Variety Trials in Greenlee County, 1990

      Clark, Lee J.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Seven grain sorghum hybrids were compared in replicated tests where full season hybrids were compared against each other and with mid full season hybrids. The full season hybrids yielded from 600 to greater than 1000 pounds per acre more than the mid full season hybrids. DeKalb 69 was the highest yielding hybrid with a yield of 8784 lbs/ac, but all three full season hybrids yielded greater than 4 tons per acre.
    • Revegetation of Retired Farmland: Response of Range Grasses to Establishment Irrigations and Microcatchment Water Harvesting

      Thacker, Gary W.; Cox, Jerry R.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      In July 1987, we began an experiment to evaluate the effects of water harvesting and establishment irrigations on range grasses on retired farmland In the first two years since establishment, we measured significantly higher forage production where we applied establishment irrigations. After three years, the difference from irrigation was no longer significant. We have not detected any significant differences in forage production due to water harvesting treatments.
    • Double Crop Corn Variety Trial, Graham County, 1990

      Clark, Lee J.; Cluff, Ronald E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Eight corn hybrids, including one white hybrid, were grown in the lower end of the Safford valley as a double crop following wheat. A tornado came through the valley flattening the field where the test was located. The crop recovered and was harvestable, but the resulting yields were undoubtedly lower than they would have been. Nevertheless, the top hybrid yielded nearly three tons and the production and crop value were about the same as a nearby field of double crop milo. It is felt that lack of corn harvesting and drying equipment in the area will likely slow the development of this crop in the area.
    • Pinto Bean Variety Demonstration in Bonita, Graham County, 1990

      Clark, L. J.; Marcarian, V.; Cluff, R. E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Nine pinto bean varieties were tested in the Bonita area of Graham county as a follow up to the tests the previous two years. The top yield in 1990 was nearly 1700 pounds per acre compared with 3200 to 3000 for 1989 and 1988, respectively. Late planting early frost and bean rust all figured into the reduced yields. Additionally, a replicated, small plot test was planted to eleven different species of beans as diverse as garbanzo, lima and kidneys. Yield results and comments on these beans adaptability to the area are included in this report.
    • Row Spacing Effects on Small Grain Varieties at Maricopa

      Ottman, M. J.; Sheedy, M. D.; Ramage, R. T.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      A 12-inch row spacing is commonly used to evaluate small grain varieties at the Maricopa Agricultural Center and other experiment stations. The objective of this study was to document the interactions of varieties and row spacings. Sir barley, durum, and wheat varieties were planted in the 1989 and 1990 growing seasons at the Maricopa Agricultural Center at four planting dates (November, December, January, February) and 6 and 12-inch row spacings. At the December planting date, which is near optimum, WestBred 881 and Topaz performed best at a 6-inch row spacing while Gustoe, Aldura, Klasic, and WestBred 911 performed best at a 12-inch row spacing. Caution must be exercised when interpreting variety trials planted in 12-inch rows anti, in addition, conducted under growing conditions different from commercial practice.
    • Spring Alfalfa Insecticide Trial

      Rethwisch, Michael D.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
    • Arizona Russian Wheat Aphid Survey and Beneficial Release Report, 1990

      Clark, Lee J.; Moore, Leon; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      During 1990 the emphasis on surveying was placed in the southeastern corner of the state, where damage was found to be most severe in previous years. Estimates of the incidence of and damage caused by the Russian Wheat Aphid (RWA) were made for the entire state. These estimates indicate that small grain producers in the state lost $212,000 due to this pest in 1990.
    • Corn Hybrid Evaluations in Cochise and Southern Graham Counties, 1990

      Clark, L. J.; Schwennesen, E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      1990 was a good year for corn yields. Favorable weather and a new yellow corn hybrid have combined to produce over 13,000 pounds of corn per acre. Pioneer 3162 was the highest producer. Two other hybrids, a new entry from Northrup King (N8318) and a new entry from Germain's (GC 5247) produced yields greater than 12,000 pounds per acre and all of the entries yielded over 10,000 pounds per acre. The white corn trial in Elfrida also showed good production with three of the ten entries yielding over 9,000 pounds per acre. DeKalb 703W yielded highest with Conlee 113W and DeKalb 77W following closely.
    • Nitrogen Fertilizer Rates for Barley Bred for Reduced Water Use

      Ottman, M. J.; Doerge, T. A.; Sheedy, M. D.; Ramage, R. T.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Barley lines have been developed for one-irrigation conditions. The purpose of these studies is to provide information required to develop recommendations for nitrogen fertilizer practices for one - irrigation barley. A total of nine field studies were conducted at the Marana and Maricopa Agricultural Centers testing six nitrogen rates ranging from 0 to 200 lbs N/A under a variety of conditions. The optimum nitrogen fertilizer rate ranged from 0 to 40 lbs N /A. No relationship was established between optimum nitrogen fertilizer rate and preplant soil nitrate, previous crop, planting date, or number of irrigations (1 vs. 2). Based on the results of this and other studies, a nitrogen rate of 40 to 50 lbs N/A is usually adequate for one-irrigation barley, and nitrogen rates greater than 80 to 100 lbs N/A is considered excessive.
    • Timing of the First Irrigation in Corna nd Moisture Stress Conditioning

      Ottman, M. J.; Jama, A. O.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Delaying the first irrigation is thought to encourage root growth and condition crops for stress later in the season. Our objective was to test this common practice using corn. Field studies were conducted in Tucson, Arizona in 1989 and 1990 in which the first irrigation was applied at the Z 4, or 8 -leaf stages, and then either irrigated or stressed at anthesis. Delaying the first irrigation either restricted or did not influence root growth. Water use during anthesis was increased if the first irrigation was delayed, especially at the 2 to 3-foot depth. Delaying the first irrigation delayed silking by approximately 3 days and decreased the rate of dry matter accumulation. Grain yield was decreased 20% and total plant yield was decreased 14% in 1990 where the first irrigation was delayed past the 2 -leaf stage and the crop was well- watered at anthesis. Timing of the first irrigation did not affect yield if irrigations were withheld at anthesis. Delaying the first irrigation does not appear to condition corn for moisture stress later in the season, and may substantially decrease yield in certain situations.
    • Revegetation of Retired Farmland: Evaluation of Six Range Grasses under Three Irrigation Regimes

      Thacker, Gary W.; Cox, Jerry R.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      In July of 1986, we seeded buffelgrass, klein grass, "Catalina" lovegrass, "Cochise" lovegrass, bottlebrush, and sideoats grama grass on retired farmland in the Avra Valley west of Tucson. We seeded these grasses under three irrigation regimes: no establishment irrigation, two establishment irrigations, and four establishment irrigations. In measurements of the standing forage in 1987 -90, four establishment irrigations significantly increased the standing forage over the unirrigated treatments. However, the two irrigation treatment was not significantly different from either four irrigations or no irrigations. Buffelgrass, klein grass, and the lovegrasses appear to be promising species for vegetative cover for this site. We have also measured significant increases in the standing forage over the last four years.
    • Alfalfa Variety Demonstration at the Safford Agricultural Center, 1990

      Clark, L. J.; Carpenter, E. W.; Cluff, R. E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Yields are given for 22 varieties of alfalfa grown at the Safford Agricultural Center. Yields were 2 to 3 tons lighter than those in 1989. Mecca retained its number one position with a yield of 8.86 tons per acre and a total of five varieties had yields above 8 tons per acre. It is of interest to note that three of the top five varieties were developed by the Plant Genetics group in California.
    • Describing the Tradeoffs Between Persistence and Productivity in Alfalfa

      Hotchkiss, Jay R.; Smith, Steven E.; Conta, Debra M.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Substantial plant loss is a commonly accepted phenomenon in commercial alfalfa production. Frequently less than 2% of the seeds originally sown are present in productive mature stands. Optimum yields may not be achieved if the small proportion of plants that survive do not represent the most productive individuals in the original population. We began a study in 1989 to describe the relationships between survival (persistence) and productivity in alfalfa. Sixty 5 yr-old plants were dug from a field of CUF -101 in Pinal Co. (= "Persistent population "). Field performance of progenies of these plants were compared with those of 60 greenhouse -grown CUF-101 plants (= "Random population ") in a 2-yr study in Tucson. In the second year of production spring and fall forage yield and average rate of stem elongation were significantly lower in the Persistent population than in the Random population. These data suggest that plants that are able to persist for the average life of a stand may represent a subset of the original sown population which exhibit more conservative growth patterns. This indicates that simultaneous selection for traits associated with productivity and persistence may be necessary in alfalfa breeding.
    • Wheat Yields Following Layby Herbicide Applications to Cotton Grown with Reduced Tillage

      Thacker, Gary W.; Coates, Wayne E.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      This experiment was conducted to quantify herbicide carry -over effects on wheat, after plowing the cotton down with conventional and reduced tillage systems. Cotton layby applications of cyanizine, diuron, and prometryne at 1.5 lbs/Ac active ingredient did not result in wheat yields that were significantly different from the untreated checks within any of the tillage systems.
    • Improved Late Season Nitrogen Fertilizer Management with Irrigated Durum Wheat Using Stem Nitrate Analyses

      Doerge, T. A.; Ottman, M. J.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      A field experiment was conducted on a Trix clay loam at the Maricopa Agricultural Center to 1) determine the optimum rates of late season N needed to achieve optimum yield and quality of irrigated durum wheat in conjunction with varying rates of early season N, and 2) to evaluate the usefulness of stem NO₃⁻N analysis in predicting the late season N rates which optimize grain production but minimize the potential for nitrate pollution of groundwater. The application of 75, 150 and 300 lbs. N/a during vegetative growth resulted in wheat with highly deficient, slightly deficient and excessive N status at the boot stage as indicated by stem NO₃⁻N analysis. The application of 60 lbs. N/a at heading to highly N-deficient and slightly N-deficient wheat resulted in grain protein levels of 12.7 and 14.3 % respectively but had little effect on grain yield. Applications from 0 to 60 lbs. N /acre at heading to wheat which had previously received excessive N did not affect grain yield but did increase grain protein levels from 15.2 to 17.4 %. The use of stem NO₃⁻N analysis appears to be a useful tool in predicting the minimum N rate to be applied during the early reproductive period to insure acceptable levels of grain protein at harvest in cases where N status during the vegetative period was not highly deficient.
    • Alfalfa Variety Trials in Greenlee County, 1986-90

      Clark, L. J.; Schneider, M. A.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Ten alfalfa varieties, ranging from very non - dormant to moderately dormant cultivars, have been grown and yields compared over a five year period. The yields decreased dramatically this last year, to 5.3 tons per acre down from 10 tons per acre during the second season. Differences in production between the top and bottom varieties was 4.75 tons per acre. Figuring hay values at $100 per ton, this difference would mean a loss of $19,000 over the 5 year period on a 40 acre field.
    • Small Grain Variety Comparisons at the Maricopa Agricultural Center 1991

      Sheedy, M.; Ottman, M.; Ramage, T.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Yield trials were conducted at the Maricopa Agricultural Center during the 1990 -91 growing season. Barley, Durum and Wheat varieties as well as experimental lines from various seed companies were tested for yield performance. Gustoe and Sunbar 409 barleys, Turbo and Aldura durum wheats; and 911 and Klasic bread wheats were the highest yielding commercial varieties in this yield trial.
    • Russian Wheat Aphid Survey in Southeastern Arizona, 1990

      Clark, Lee J.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      Fifteen small grain fields, including eight wheat fields, two barley fields and five oat fields, throughout the grain growing areas of Graham, Greenlee and Cochise counties were surveyed weekly from the third week in March through the second week in June, to document the presence of Russian wheat aphid (RWA), other aphid, parasites and predators. RWA were found in all three counties and in all three grains. Presence of RWA caused chemical pest control applications in approximately 19%, 33% and 90% of the small grain fields in Graham, Greenlee and Cochise counties, respectively. Thirty three percent of the fields had beneficial parasites and predators were found 93% of the fields. Presence of parasites reduced the RWA populations in 80% of the cases and presence of predators had a dramatic effect on other aphids and was felt to be beneficial in controlling RWA.
    • The Use of AZSCHED to Schedule Irrigations on Wheat

      Clark, Lee J.; Carpenter, Eddie W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1991-09)
      AZSCHED irrigation software was used to schedule irrigation on Aldura wheat on the Safford Agricultural Center with very good results. Irrigations were scheduled at 40%, 50% and 60% calculated soil water depletion throughout the critical part of the growing season. The plots being irrigated at 40% depletion yielded the most and had the highest water use efficiency and showed the least plant stress. Comparing data with previous experiments, it was noted that increased inputs of higher seeding rate and higher nitrogen rate also increased the water use efficiency.