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Fluid Journal : Spring 2015
11 The Fluid Journal Spring 2015 In the fall of 2010 the Kansas Board of Trade proposed and passed quality standards on No. 2 Hard Red Winter Wheat, in which any wheat that fell below 10.5 percent would be considered undeliverable. This new standard significantly increased the interest of late- season N applications to increase grain protein in the Southern Great Plains. It has been a practice widely used and accepted in the Northwest and Eastern US, relative to spring wheat production. However, in the Southern Great Plains, late-season N applications are not widely used. Average yield levels of the region often do not support additional trips over the field. In a 2002 field study by Woolfolk, et al., it was reported that when UAN and ammonium sulfate were applied to winter wheat pre- and post-flowering, grain N concentration was increased. However, producers in the region are commonly making fungicide applications during flag leaf stage. This presents an opportunity to apply fertilizer N with no additional application cost. To this point, many producers are putting one to two gallons of low salt N products in with the flag leaf fungicide application in hopes of either improved yield or increased grain protein levels. Trial specifics Evaluation. This trial was established to evaluate the use of two N sources applied The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Spring 2015 • Vol. 23, No. 2, Issue #88 Drs. Brian Arnall, Brad Seaborn, Jeremiah Mullock, and Mr. Brandon Burgess Post flag leaf has been too variable to draw conclusions. Summary: In our studies across the six site years, late-season foliar nitrogen (N) never impacted yield in either a positive or negative manner when compared to the standard fertility treatment. The response to overall measured variables, which included protein, mix tolerance, and loaf volume, was very variable and not consistent. Oklahoma’s post-flag leaf environment may be too variable to say, conclusively, that late-season foliar application would improve the baking and milling qualities of hard red winter wheat. flag leaf (FL) and post anthesis (PA) to improve Great Plains hard red winter wheat grain yield, protein, and milling and baking characteristics. Sources. The two sources evaluated were UAN 28-0-0 and CoRoN 25-0- 0. CoRoN (which is labeled as being derived from urea, methylene diurea, and methylene urea) was selected due to its low salt level and wide availability within the region. Rates. Protein levels were maximized at a rate of 34 kg N ha-1 (Woolfolk et al., 2000). However, the greatest majority of the low salt N fertilizers is not being recommended at a rate above 18 L ha-1 or as, in the case of CoRoN, 7.6 hg N ha-1 . Therefore, it was important to evaluate rates below that which Woolfolk looked at. Both N sources were applied at three rates (6.7, 13.4, and 26.8 kg N ha-1) at the two timings FL and PA. Applications were made using a CO2 pressurized backpack sprayer. All treatments were supplied at a flow rate of 93.8 L ha-1 with water as the carrier. Typically, FL applications occurred in mid-April while PA applications were made in mid to late May. The constant flow rate was chosen to ensure uniform application of the fertilizer. All treatments, excluding the non-fertilized check, received 45 kg N ha-1 pre-plant and 45 kg N ha-1 at top- dress. Unlike the Woolfolk work, where treatments were applied in the cool of the morning to reduce the likelihood of tissue burn, the treatments for this study were all applied mid-day. However, the use of water as a carrier likely reduced tissue burn, at least for the lower N rates. Location. The trials were established at two locations: Lahoma and Lake Carl Blackwell (LCB). Figures 1, 2, and 3 document the deviation in plant-available water, average daily temperature, and relative humidity from the long-term average values for each year of the study at the Lahoma site. Treatments. Our study consisted of 14 treatments, which included a non-fertilized and a fertilized control arranged in a RCBD. Plot size measured 3m by 6m. Harvest. At maturity, the grain was harvested from the center 1.5 m of each plot with a Massey 8XP combine. Evaluation. All grain from each plot was retained and sent to the USDA ARS Baking and Milling lab in Manhattan KS for evaluation of milling and baking qualities. Samples. It should be noted that all samples from the 2013 harvest were lost when packaging was damaged during the shipping process. Therefore, for the 2013 crop year, only yield data are available. Baking, milling variables Recommended Quality Targets (RQT) are set by the HWW Quality Target What About Late Season Application of Foliar N? ▼ DOWNLOAD