• Barley and Durum Response to Phosphorus at Buckey, Maricopa, and Yuma, 1997

      Ottman, M. J.; Husman, S. H.; Tickes, B. R.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Soil tests were developed in the 1930's as a guideline for phosphorus fertilizer application. The phosphorus soil test for the calcareous soils in the Western U.S. is based on bicarbonate extraction and is often called the Olsen P method. Phosphorus fertilizer recommendations for small grains based on this test are remarkably similar across the Western states. Despite the availability of this test, its proven accuracy (93% in California), and its low cost ($1 /acre), most farmers in Arizona apply phosphorus fertilizer to their small grains crops without the benefit of a preplant soil test. The purpose of this study was to demonstrate the effectiveness of the soil test in predicting a response to phosphorus fertilizer. At Maricopa, the soil test P was 8.1 ppm, a variable response to P fertilizer was expected, and a variable response to P fertilizer was obtained. We were able to detect a response to P fertilizer at this site with only 1 out of 4 varieties, and the response averaged across varieties was 336 lbs /acre or a 6% increase. No response to P fertilizer was obtained on a commercial farm in Buckeye where the soil test P was 22 ppm and a response was not expected. At the Yuma-Mesa site, the preplant P level was also 22 ppm, and a yield increase of29% (1442 lbs /acre) was measured on barley even though a response was not expected. The soil on the Yuma -Mesa is 95% sand and perhaps the soil test for P needs to be adjusted for this soil type, but at the other sites tested, the current soil test recommendations for P seem to be accurate.
    • Barley and Durum Response to Seeding Rate at Maricopa and Yuma, 1996-97

      Ottman, M. J.; Tickes, B. R.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      A poor stand as a result of a low seeding rate can cost the grower due to decreased yield potential. A seeding rate higher than optimum can also cost the grower not only due to increased seed cost but also due to increased susceptibility to water and nitrogen stress and frost damage. Seeding rates in small grains are usually expressed on a pound per acre basis, but since varieties differ in seed size, different amounts of seed can be planted at equivalent seeding rates. Defining optimum seeding rates are also complicated by the fact that the number of seeds that actually emerge can vary depending on planting conditions. In our studies, emergence varied from 50 to 100% emergence. At the Maricopa location, the optimum seeding rate was obtained with 12 seedlings per square foot, which corresponded to a seeding rate of 75 lbs /A for the small seeded Brooks wheat and 125 lbs seed /A for the large seeded Kronos durum. No differences in yield were detected at the Yuma Mesa location for barley seeding rates ranging from 75 to 150 lbs seed/A or at the Yuma - Valley location for durum seeding rates from 200 to 250 lbs seed/A. Growers generally seed at rates higher than the optimum suggested by this and other studies, but current commercial seeding rates are seen as cheap insurance against stand establishment problems and may or may not be warranted depending on seedbed conditions and percent emergence.
    • Barley Variety Trial on the Safford Agricultural Center, 1997

      Clark, L. J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Sixteen varieties of barley were tested at the Safford Agricultural Center in 1997. Nebula, a new variety from Western Plant Breeders, was the highest yielding variety in the trial with a yield over 5100 pounds per acre. Nebula also had the highest bushel weight of the varieties tested.
    • Intensive Cereal Management for Durum Production, Buckeye and Yuma, 1996-97

      Ottman, M. J.; Husman, S. H.; Tickes, B. R.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      The highest wheat yields in the world are obtained using a growing system called intensive cereal management (ICM). High yielding varieties are planted at high seeding rates, treated with foliar fungicides, plant growth regulators are applied to control lodging, and high nitrogen fertilizer rates are used to obtain high yields. The ICM system adapted to Arizona does not include fungicide treatments due to our lack of leaf diseases. We tested the effect of ICM on yield, grain protein, and other characteristics at three commercial farms in Arizona. ICM resulted in higher protein in one case due to increased nitrogen application and reduced height in another case due to the plant growth regulator. However, in most cases, we were not able to detect an affect of ICM on the crop, and the increased input cost was not paid for by increased crop performance. Intensive cereal management does not appear to hold much promise under our conditions except perhaps in cases where lodging is predictable or yields do not reach their potential.
    • Irrigation Scheduling on Barley at the Safford Ag Center, 1997

      Clark, L. J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      An irrigation study on barley was made to determine the economical consequences of irrigating the crop when an irrigation scheduling program called for an irrigation compared to waiting 3 to 6 days for a water turn, from the ditch. The plots irrigated when the soil moisture depletion level reached 40% produced the highest yield. Yields were decreased 700 and 1000 pounds respectively for waiting 3-4 days and 6-7 days, respectively. The economics of using the pump are discussed and a chart is given to help determine a break - even point.
    • Late Season Nitrogen Fertilizer for Durum at Buckey, Casa Grande, and Vicksburg, 1996-97

      Ottman, M. J.; Knowles, T. C.; Husman, S. H.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Research conducted recently suggested that application of nitrogen fertilizer from flowering until the dough stage could increase grain protein concentration in durum even if nitrogen applications earlier in the season were adequate for optimum yield. We tested the ability of late season nitrogen application to increase protein at commercial farms in Buckeye, Casa Grande, and Vicksburg. Late season nitrogen increased protein by nearly two percentage points in two out of the three locations. No response was measured at the third location possibly due to high rates or nitrogen earlier in the season. The cost of the late season fertilizer at 35 to 50 lbs N /acre was about $15 /acre. The fertilizer was paid for at the two location where a response was obtained by 1) the slight yield increase of 310 lbs /acre which was worth about $23 /acre and 2) the difference in dockage or premiums paid for protein which was worth about $38 /acre. It is possible that lower stem nitrate levels could be used to determine whether or late applications of nitrogen will increase protein, but we currently do not have a method to determine if protein will be over the critical level of 13% or if HVAC will be over the critical level of 90 %.
    • Late Season Water and Nitrogen Effects on Durum Quality, 1996

      Ottman, M. J.; Doerge, T. A.; Martin, E. C.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Durum grain quality is affected by many factors, but water and nitrogen are factors that the grower can control. The purpose of this research was to determine 1) the nitrogen application rate required at pollen shed to maintain adequate grain protein levels if irrigation is excessive or deficient during grain fill and 2) if nitrogen applications during grain fill can elevate grain protein. Field research was conducted at the Maricopa Agricultural Center using the durum varieties Duraking, Minos, and Turbo. The field was treated uniformly until pollen shed when nitrogen was applied at rates of 0, 30, and 60 lbs /acre. During grain fill, the plots were irrigated based on 30, 50, or 70% moisture depletion. In a separate experiment, nitrogen fertilizer was applied at a rate of 30 lbs N /acre at pollen shed only, pollen shed and the first irrigation after pollen shed, and pollen shed and the first and second irrigation after pollen shed. Increased irrigation frequency during grain fill decreased HVAC from 93 to 81%. Increasing nitrogen rate at pollen shed from 0 to 30 and 30 to 60 lbs N /acre increased protein from 11.6 to 12.5% and 12.5 to 13.3% and increased HVAC from 79 to 89% and 89 to 94 %. Nitrogen fertilizer application at the first irrigation after pollen shed increased grain protein content from 12.9 to 13.6% and application at the first and second irrigation after pollen shed increased grain protein content further to 14.1% averaged over varieties. Nitrogen fertilizer application during grain fill may not be too late to increase grain protein content.
    • Quick Tests for Sap Nitrate in Small Grains, Maricopa, 1997

      Ottman, M. J.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Nitrate content of the lower stem tissue of small grains is used as a guideline for nitrogen fertilization. The turnaround time for nitrate analysis in a commercial lab is usually 1 to 3 days. Nitrate quick tests have been suggested as a means of obtaining results on a more timely basis. The quick tests analyze nitrate in the sap or juice squeezed out of the tissue. A nitrate test conducted by a commercial lab is performed on the dried and ground tissue. In this study, I found that the quick tests on plant sap are not as accurate as conventional tests on dried tissue since the moisture content of the fresh plant tissue varies depending on its nitrate content and the growth stage of the plant. We compared the following quick test methods: nitrate test strips, a colorimetric procedure, and a hand held nitrate electrode. Nitrate test strips were not sensitive enough to be useful and were difficult to compare to the color charts. An electronic strip reader could alleviate this difficulty and make the strips a viable option. Colorimetric procedures, or those that rely on nitrate producing a colored solution with certain chemicals added, are not adapted to analyzing plant sap since the green color and organics in the sap interfer with the color produced by the nitrate. The hand held nitrate electrode, or Cardi meter, was the simplest and most accurate method we experimented tested. Quick tests for nitrate in the sap have the following disadvantages: 1) It is not easy to squeeze the sap out of the plant tissue, 2) The sap needs to be diluted to fit into the analytical range of the test, and 3) The moisture content of the tissue needs to be accounted for somehow for the results to be most accurate.
    • Small Grains Variety Evaluation at Marana, Maricopa, Paloma, and Yuma, 1997

      Ottman, M. J.; Husman, S. H.; Lindahl, D. A.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Small grain varieties are evaluated each year by University of Arizona personnel at one or more locations. The purpose of these tests is to characterize varieties in terms in terms of yield and other attributes. Variety performance varies greatly from year to year and several site years are necessary to adequate characterize the yield potential of a variety. The results contained in this report will be combined with results from previous years in a summary available from Arizona Cooperative Extension.
    • Use of Agrotain to Prevent Urea Volotilization in Irrigated Wheat Production, Casa Grande 1996

      Ottman, M. J.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)