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Fluid Journal : Fall 2014
7 The Fluid Journal Fall 2014 Physically Evaluating Wheat Straw Decomposition Via Different Fertilizer Treatments Study samples indicate longer fertilizer application periods can decompose more crop residue. The Fluid Journal • Official Journal of the Fluid Fertilizer Foundation • Fall 2014 • Vol. 22, No. 4, Issue #86 Yuxin He, Drs. DeAnn Presley and John Tatarko Summary: Summer samples from our Colby site fall treatment plots had less aboveground biomass than spring treatment plots, indicating a longer fertilizer application period can decompose crop residue. Specific energy also seems more sensitive to fertilizer application timing and shear stress is more affected by fertilizer rates. Meanwhile, more detailed analyses on the effect of different nitrogen (N) and sulfur (S) rates on wheat- straw decomposition will be conducted. ▼ DOWNLOAD The importance of crop residue to soil quality has been gradually learned and recognized by researchers and farmers, particularly in the semi-arid area, where precipitation is limited. Lacking residue protection, surface soil is vulnerable to negative environmental and anthropogenic influences, such as: • Wind blow • Precipitation strike • Dramatic temperature change due to solar radiation • Animal traffic • Agricultural equipment compaction. In western Kansas, wind erosion might be the most significant soil degradation process due to the local climate characteristics. By removing the most fertile layer of soil, lowering water holding capacity, degrading soil structure, and increasing soil variability, wind erosion can reduce soil productivity significantly in certain areas. Producers adopt no-till farming more and more today owing to fewer disturbances of the soil and better retention of crop residue on the ground. Research has demonstrated that indiscriminate removal of crop residue can drastically reduce the erosion benefit from no-till farming. Therefore, crop residue has largely remained in the field after harvest in order to lower the possibility of wind erosion in some regions today. On the other hand, by having such large amounts of crop residue on the field, farmers usually report problems about establishing a good plant stand in high residue situations. Dry regions have a climate that is not as conducive to residue decomposition as the more humid regions. As a result, some producers resort to tillage as a means for decreasing residue to allow them to get a better stand, which sacrifices the many benefits gained from the no-till system. In 2013, global wheat production was expecting a 4.3 percent increase to 690 million tons (FAO, 2013). Unlike other crop residues, wheat-straw is usually not considered for animal husbandry or other use (i.e., mushroom composing mixture). Therefore, wheat-straw more likely would remain in the field after harvest. One recommendation extension specialists make is to apply N fertilizer as urea ammonium nitrate (UAN) in a fine mist on the residue to stimulate microbial activity and subsequent decomposition of the residue. Meanwhile, as a secondary nutrient, S can be a limiting factor to higher microbial activity, especially after cultivation of high S demand plants such as alfalfa. Therefore, ammonium thiosulfate (ATS) is also considered to stimulate crop residue decomposition. The objectives of this research are to: • Conduct on-farm research to evaluate the effect of different UAN and ATS application rates on the decomposition of wheat- straw • Study the timing of UAN application and the effects of decomposition of residue. Methodology Sites. The research sites were established in Western Kansas in 2011 and 2012, right after the wheat harvest. They were in Hays, Colby, and Garden City, respectively. Block design. A randomized, complete block design with four replications was conducted in the experiment. Plots at each site were made in 6.1 meter by 6.1 meter size and were placed directly over the center of where the combine traveled. Application rates. The plots had UAN