The results of this study support the practice of not applying nitrogen at planting time even if the soil N level is low. Highest yields were obtained if the nitrogen that would have been applied at planting time was applied at the 5-leaf stage in addition to the N that would normally be applied at this time. If the preplant N application is skipped, the crop nitrogen status must be monitored carefully and N fertilizer should be applied by the 5-leaf stage to avoid a yield reduction. If a large amount of N is applied at the 5-leaf stage, lodging may be encouraged.

Small grain varieties are evaluated each year by University of Arizona personnel. The purpose of these tests is to characterize varieties in terms of yield and other attributes. Variety performance varies greatly from year to year and several site-years are necessary to adequately characterize the yield potential of a variety. A summary of small grain variety trials conducted by the University of Arizona can be found online at http://ag.arizona.edu/pubs/crops/az1265.pdf.

Phosphorus fertilizer represents a significant portion of the cost of producing small grains. Some evidence exists that there are differences in the ability of small grain varieties to take phosphorus up from the soil and utilize this nutrient in the grain. The objective of this study is to determine if barley and wheat varieties grown in Arizona differ in their response to phosphorus fertilizer. A study was initiated at the Maricopa Agricultural Center testing the response of 7 barley and 13 wheat (12 durum wheat and 1 bread wheat) varieties to 2 phosphorus rates (0 and 100 lbs P2O5/acre). The grain yield increase due to phosphorus application averaged across varieties was 474 lbs/acre for barley and 613 lbs/acre for wheat. The barley varieties differed in their grain yield increase due to phosphorus fertilizer and the greatest increase for the commercial varieties tested was 906 lbs and the smallest increase was 245 lbs. We have no statistical evidence that wheat varieties differed in their response to phosphorus fertilizer. The lack of response to phosphorus fertilizer for a particular variety may save production costs if the fertilizer is not applied, but a significant response to phosphorus fertilizer may pay for the fertilizer cost and increase profits. In this study, the higher yielding varieties tended to have a greater response to phosphorus fertilizer, particularly for the barley. This test will be repeated in 2010 to see if the results obtained this year can be duplicated.

Small grain varieties are evaluated each year by University of Arizona personnel. The purpose of these tests is to characterize varieties in terms of yield and other attributes. Variety performance varies greatly from year to year and several site-years are necessary to adequately characterize the yield potential of a variety. A summary of small grain variety trials conducted by the University of Arizona can be found online at http://ag.arizona.edu/pubs/crops/az1265.pdf.

Solum is a barley adapted to one or two irrigations but the grain produced is often low in test weight. Studies were conducted on two commercial farms near Maricopa and Coolidge in an effort to verify data from previous studies suggesting that delaying the first post-emergence irrigation until boot increases test weight compared to earlier irrigation, but does not affect yield. The irrigation treatments consisted of 1) two irrigations – planting and boot, or 2) three irrigations – planting, 5- to 6-leaf stage, and heading (grower standard). The irrigation treatments had no effect on grain yield, test weight, kernel weight, or lodging at either location, but delaying the second irrigation until boot reduced plant height at Coolidge. Despite the lack of positive results from these studies, applying the second irrigation at boot may still be preferable to earlier applications because of reduced plant height and the risk of lodging. We have not been able to measure a benefit from a third irrigation for Solum barley in these or previous studies.

Five herbicides were evaluated for the control of littleseed canarygrass. These herbicides were applied at either the 1-3 leaf stage of the canarygrass or at the 1 leaf to elongating stage of development. All of the herbicides tested except Hoelon, produced excellent control at the early application. Puma, Olympus and the highest rate of F130060 (Aventis) produced good control at the late application. Achieve worked well when applied early but was unacceptable at the late application.

This study was initiated in 2003 in response to a push by one of the grain buying companies to produce more durum wheat for export from Arizona. The export market required a minimum of 13% protein and other quality constraints. A nitrogen timing regime was established by the University to provide the crop with this nutrient according to its physiological development. This study had four nitrogen application treatments addressing different ways to provide the crop with its nitrogen needs. This second year of the study showed statistically different yields from the treatments applied and different inferences from the first year of the study. An economic analysis is included to show the profitability of nitrogen applications for this year and an economic summary for the last four years of nitrogen studies on durum wheat.

Three herbicides, Puma, Achieve and Osprey, have been registered for the control of Littleseed Canarygrass in the last five years. Another, Pinoxaden, is being developed and should be registered in the next few years. These herbicides were compared for weed control and crop safety. All produced very good to excellent levels of control although crop injury, especially when tank mixed with broadleaf herbicides, was significant.

This study is a follow-up on a study initiated three years ago with an emphasis on the timing of application of nitrogen (N) fertilizer. The times targeted in this study were: at planting, at initiation of growth and at boot stage. A nitrogen starter fertilizer at planting increased yields over 100 pounds of grain per acre for both wheat and barley compared with plots which did not receive the added nitrogen at planting. No difference was seen between applying 46 or 92 pounds of N per acre as a starter fertilizer. Amount of N added at boot stage seemed to increase barley yields slightly but had no effect on wheat yield nor protein content. An economic analysis is included to show the profitability of nitrogen applications.

This two year study is a follow-up to a study started in 1999, looking at phosphorus applications at planting on wheat and barley. Treatments applied were 0, 100, 200 and 400 pounds of 16-20-0 planted through the grain drill with the seed. Phosphorus applied at planting improved yields in most replicates, but because of the cost of the fertilizer, the higher yields were not always the most economically profitable.