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Fluid Journal : Fall 2014
11 The Fluid Journal Fall 2014 Mr. He and Dr. Presley are in the Department of Agronomy, Kansas State University, Manhattan, KS and Dr.Tatarko is in USDA-ARS, Manhattan, KS energy from the samples taken in Hays. The specific energy of wheat straw from spring application plots is significantly lower than from fall application plots. One reason to cause this may be attributed to the strong winds. Apparently, highly decomposed residues are more easily blown away from some plots than others due to the weaker structure and lighter mass. Therefore, less decomposed residue may have a higher chance of remaining in the field. Thus, there was a higher possibility of collecting less decomposed samples from the field that gave higher specific energy. For the shear stress of summer 2012, the Hays sample Urea60, with a fall 2011 application treatment, had significantly lower shear stress (Figure 9). It indicates a longer reaction period and a higher N rate can increase the decomposition speed. Similar to the specific energy, ATS seems to have no effect on the decomposition rate of wheat straw. Colby. For samples from the Colby site in the summer of 2012, fall treatment plots had less aboveground biomass than spring treatment plots, indicating that a longer fertilizer application period can decompose more crop residue. Also, from the current results, specific energy seems more sensitive to fertilizer application timing and shear stress is more affected by fertilizer rates. Looking ahead We are going to conduct more detailed statistical analyses for better understanding of the effect of different N rates and S rates on wheat-straw decomposition. Meanwhile, chemical analyses are also in process. Total carbon and total N will be reported. We strongly favor chamber studies for better control on environmental variables such as wind, moisture, soil type, temperature, and solar radiation. Figure 7. Effects of different treatments on specific energy of samples from Hays with spring 2012 fertilizer application. Figure 8. Timing effect on specific energy of samples from summer 2012, Hays. Figure 9. Effects of different treatments on shear stress of samples from Hays with fall 2011 fertilizer application..