• Irrigation Timing Effects of Soil Trigger Applications of Alfalfa Hay Yield

      Rethwisch, Michael D.; Torres, Miguel; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      The plant growth regulator Soil Trigger was applied in basin flood irrigation water to the first (following previous cutting) and last irrigations of a third year stand of CUF 101 alfalfa before a late June 1995 harvest. Effect of product on yield may have been limited by pH as irrigation water pH was approximately 7.9. An increase in yield was noted with product usage, with a greater yield increase noted when applied earlier in crop cycle (first irrigation = 136 lbs hay /acre) rather than later in crop development cycle (last irrigation = 34 lbs hay /acre) when compared with the untreated check Yield from the next (July) harvest was not obtained Yield differences were not statistically different or economic for a single harvest in this experiment. Alfalfa quality was not obtained.
    • Kenaf Varietal Evaluation in the High Desert of Southeastern Arizona

      Clark, L. J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Several Kenaf varieties have been grown at the Safford Agricultural Center over a period of 5 years. Plants harvested green have produced yields in excess of 40 tons per acre. Air dried stems that would be useful for commercial products have yielded as high as 9.5 tons per acre and two varieties, Tainung 2 and Everglades 71, have averaged nearly 7 tons per acre. In addition to yields and other agronomic values of the varieties tested, an economical discussion is made on the feasibility of Kenaf production on southeastern Arizona.
    • The Last Irrigation in Durum at Buckey, Casa Grande, and Marana, 1996-97

      Ottman, M. J.; Husman, S. H.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Based on consumptive use, the last irrigation in wheat may be applied by the soft dough stage on the average sandy loam soil without loss of yield or shriveled grain. In two of the three locations reported here, this was the case although one of the soils was a clay loam. At the Buckeye location, applying the last irrigation at the soft dough stage resulted in a yield loss of 406 lbs /acre, but this yield loss was not statistically significant at conventional probability levels. Nevertheless, terminating irrigation at the soft dough stage is somewhat risky, and a less risky time to terminate irrigations may be between soft dough and hard dough for a sandy loam soil. The problem with this generalized recommendation is that neither soft dough nor hard dough are well -defined crop growth stages and sandy loam soils may vary greatly in their water -holding capacity. Also, it may be profitable to apply a final irrigation to carry late, green tillers to maturity. Assuming a water cost of $15 per irrigation and a grain value of $8 /cwt, a yield increase of 190 lbs /acre would pay for a final irrigation. Therefore, if water is inexpensive, terminating wheat irrigations unnecessarily early is not worth the risk of decreased revenue. Once the heads have turned color from green to brown, the crop has reached maturity and additional irrigations at this time will not affect yield even if other parts of the plant are green.
    • 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.
    • National Dry Bean Nursery Summary, 1992-95

      Clark, L. J.; Carpenter, E. W.; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      A yield summary of selected varieties from the National Dry Bean Nursery from 1992 to 1995 are contained in this paper. Average and individual yields vary from year to year depending on the planting dates and the weather of the given year. Looking at a four year average for a variety gives a better estimate of its yield potential than any single year study.
    • Overview of Alfalfa Production and Market Trends in La Paz County

      Knowles, Tim C.; Winans, S. Sherwood; Ottman, Michael (College of Agriculture, University of Arizona (Tucson, AZ), 1997-10)
      Alfalfa producers in the Colorado River region of La Paz County have experienced some shifting trends in markets and production over the last 15 years. Acreage has increased steadily from a low of 25,000 acres in the early 1980's to a high of nearly 45,000 acres in 1997. Average annual alfalfa hay yields in La Paz County have maintained a fairly flat trend ranging from 7.5 to 8.5 tons per acre during this time. Alfalfa hay prices were severely depressed during the summer of 1986, from summer of 1991 through winter of 1992, and during the summer of 1995. In contrast, La Paz County alfalfa hay producers experienced the strongest markets during the winters of 1984, 1990, and 1995. More recently, since the winter of 1996, producers have experienced the strongest alfalfa hay market in the history of La Paz County with on farm prices reaching an all time high of $136 per ton.
    • 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)