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Fluid Journal : Late Spring 2012
Late Spring 2012 The Fluid Journal 02 Summary: Across both locations no evident trends in grain yields developed but trends were found in grain protein results. Lack of response in yield due to late-season applications of N is not unexpected, especially considering the environment. Extreme heat and drought during the spring and summer drew soil moisture from depth, likely contributing a great deal of additional NO3 during periods of stem elongation through grain fill. As is often the case in field experiments, no final conclusions can be drawn from a single year’s worth of data. Initial trials evaluated on winter wheat at two stages. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Late Spring 2012 • Vol. 20, No. 3, Issue# 77 Dr. D . Brian Arnall, Mr. Jeremiah Mullock, and Dr. Brad Seabourn Can Protein Levels Be Economically Increased? One result from the 2010 hard red winter wheat harvest was an increase of discussions on protein values across the southern great plains. The crop garnered relatively low protein values for several reasons, many of which were directly related to the weather patterns and environmental conditions. The question that many in industry and production were asking was whether protein levels could be economically increased. It has been documented that late-season nitrogen (N) application (pre- and post-anthesis) can indeed increase protein, a practice that is common in the production of spring wheat. 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. Agricultural producers are regularly presented with a multitude of products that boast improved yields, protein, or efficiency. One such product is the low-salt, controlled- release specialty N fertilizer. This product is sold in large volume to be applied at flag leaf with a fungicide in an effort to increase yield, but is also used elsewhere to increase grain protein. The work performed in 2002 did not evaluate N applications prior to pre-anthesis nor did the experiment evaluate N rates as low as what is being recommended. It showed increased protein values using traditional fertilizer sources, resulting in minimal to no tissue damage. However, treatments were applied in the cool of the morning to ensure minimum burn. This is not practical on a large scale, and reduced leaf burn is one of the selling points of the low- salt products. In addition, there has been a great deal of recent discussion about the functionality of the additional N present in the grain as a result of post-anthesis applications. Trial specifics This trial evaluated the use of foliar N applications on winter wheat at two stages: flag leaf and post-flowering, using both a traditional and specialty source. Nitrogen rate also was evaluated to determine impact of N on yield and quality. This is important, as the 2002 study mentioned above reported there was a linear response to N rate up to 34 kg N ha-1 , while also cautioning that most low salt N fertilizers are not being recommended at rates of more than18Lha-1or7.6kgNha-1 . Liquid UAN was used in this study as the traditional N source, a caveat, however, in that both N sources were applied mixed with water to achieve a flow rate of 93.8 l/ha. This was done in an effort to reduce the potential for tissue damage when N is applied midday. The low-salt product used was a controlled released liquid fertilizer produced for agricultural use, containing only N and readily available in Oklahoma, in this case as CoRoN 25-0 -0 . The trials were established at two locations, Lahoma and LCB, and consisted of 14 treatments arranged in a RCBD. Table 1 shows treatment structure. At harvest, a sub-sample of grain was collected from each plot and sent to the USDA ARS Baking and Milling Lab in Manhattan, KS for evaluation of treatment impact on quality. Lahoma Yields. The Lahoma location had been fallowed the previous season, which helps explain the extremely high yields, compared to the rest of the region. At this location treatment mean yields ranged from 4,000 to
Early Spring 2012