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Fluid Journal : Fluid Journal 2008-2009
16 Fluid Journal WINTER 2008 2004 and 2004-2005 but not in the poor growth season of 2005-2006. Nitrate levels Figure 2 shows soil nitrate levels at three depths averaged across two tillage systems from 2004 through 2006. Differences in nitrate content by depth were significant each year with the 0- to 6-inch depth containing the highest nitrate levels, as expected. In 2006, nitrate content in the upper 6 inches of soil Wheat Grain Protein y = 0.023x2 + 0.1701x + 8.8609 R2 = 0.53 y = 0.062x2 + 0.1351x + 8.1346 R2 = 0.95 7 9 11 03 06 09 01 20 + 1.3204x + 6.8899 y = -0.1246x2 R2 = 0.96 y = -0.004x2 + 0.3815x + 7.7257 R2 = 0.97 7 9 11 03 06 09 01 20 Protein (%) Preplant Nitrogen Application (lbs/A) Texas Agricultural Experiment Station 1/Top-dress 2/Top-dress 1/No Top-dress 2/No Top-dress 2003-2004 2004-2005 Protein in wheat grain for treatments with and without a topdress fertilizer application of 45 lbs per acre of nitrogen 1/Protein found in wheat forage across different preplant nitrogen rates was found significantly different at P<0.05 2/Protein found in wheat forage across different preplant nitrogen rates was not found significantly different at P<0.05 Effect of nitrogen fertilizer on total and soluble protein content in winter wheat forage Vernon, Texas, 2003-04 Date Nov. 03 Dec. 03 Jan. 04 Feb. 04 Mar. 04 Apr. 04 Crude Protein (%DM) 0 10 20 30 40 30N 60N 120 N (Lbs/ac.) Total protein Soluble protein 0.01 0.001 0.001 0.1 Te xas Agricultural Experiment Station 0 10 20 30 40 50 60 1/11/2005 1/18/2005 1/25/2005 2/1/2005 2/8/2005 2/15/2005 2/22/2005 3/1/2005 3/8/2005 3/15/2005 3/22/2005 Perc ent of steers bloated Bloat Dynamics and N-Fertilization Vernon, TX. Jan-Mar 2005 120 N (25 hd) 30N (25 hd) 60N(27hd) Effect of N fertility on bloat dynamics. Te xas Agricultural Experiment Station Grazing Season (mo) Figure 3. Protein in wheat grain treatments with and without a topdress fertilizer application of 45 lbs/A of N. Figure 4. Time-course of N effect on total and soluble plant protein in winter wheat fertilized with 3 preplant N rates (data provided by Dr. W. E. Pinchak, TAES, Vernon). was considerably higher than in the previous two years, reflecting poor use of N due to crop failure. These data point to the fact that not all N is lost from one season to the next when a crop does not fully use applied N. Under these circumstances, producers should not rely on past fertilization experiences but should soil sample to determine the levels of residual N and perhaps save on fertilizer costs for the subsequent crop. Topdressing In 2004 and 2005, there was a general increase in grain protein with increased preplant N application. Topdressing N generally resulted in an additional increase in grain protein but, surprisingly, not over about 1 percent (Figure 3). Unfortunately, grain protein even at the highest levels was not considered sufficient to measurably enhance baking quality. Only one wheat variety was used in the study but early results indicate that in a dual-use system in this region it may not be possible to significantly increase grain protein with high N applications. Bloat Figures 4 and 5 show the time- course correlation between protein increase with three preplant N application rates and the degree of bloat in stocker cattle over the same period. Farmers and ranchers need to be aware of this relationship. Dr. Sij is professor/agronomist, Mrs. Dyer is research technician, and Mr. Belew is research associate at the Texas Agricultural Experiment Station in Vernon, Texas. Figure 5. Time-course of bloat development as influenced by 3 preplant N fertility rates (data provided by Dr. W. E. Pinchak, TAES, Vernon).
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