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ARS Home » Plains Area » Fort Collins, Colorado » Center for Agricultural Resources Research » Rangeland Resources & Systems Research » Research » Publications at this Location » Publication #331479

Title: Liquid N and S fertilizer solutions effects on the mass, chemical, and shear strength properties of winter wheat (Triticum aestuvum) residue

Author
item HE, YUXIN - Sichuan University
item PRESLEY, DEANN - Kansas State University
item Tatarko, John

Submitted to: American Society of Agricultural and Biological Engineers
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/22/2017
Publication Date: 6/1/2017
Citation: He, Y., Presley, D.R., Tatarko, J. 2017. Liquid N and S fertilizer solutions effects on the mass, chemical, and shear strength properties of winter wheat (Triticum aestuvum) residue. American Society of Agricultural and Biological Engineers. 60(3):671-682. doi:10.13031/trans.11961.

Interpretive Summary: Fertilizer applied to wheat straw after harvest may hasten decomposition of straw residue to improve wheat establishment where crop residue is high at planting. The use of fertilizer to stimulate microbial decomposition of residue has been debated in the agricultural research community. Field experiments were conducted to assess winter wheat straw decomposition under different fertilizer rates and application timings at three sites in western Kansas (Hays, Colby and Garden City) following wheat harvest in 2011 and 2012. Fertilizer treatments included Nitrogen (urea ammonium nitrate) applied at rates of 0, 20, 40 or 60 pounds per acre and a Nitrogen and Sulfur mixture (ammonium thiosulfate) applied at rates of 15 or 30 pounds of S per acre. A shearing device that measured the energy required to cut wheat straw was used to assess degree of decomposition. Total Carbon and Nitrogen content was also measured for bulk wheat straw samples from each plot. Differences among treatments were often observed, however, few sites and years had significant differences in wheat straw decomposition as compared to no-fertilizer. For example, fertilizer rate and timing of application during summer 2012 and fall 2013 at the Hays site had impacts on wheat straw strength. Across sites and years, earlier (fall) fertilizer application generally resulted in lower remaining residue mass as compared to a spring application. Statistical analysis suggested that Nitrogen content and the ratio of Carbon to Nitrogen can explain the results with respect to treatment effects on winter wheat residue decomposition.

Technical Abstract: To improve stand establishment in high crop residue situations, the utility of fertilizer to stimulate microbial decomposition of residue has been debated. Field experiments assessed winter wheat (Triticum aestivum) straw decomposition under different fertilizer rates and application timings at three sites in western Kansas, U.S.A. following wheat harvest in 2011 and 2012. Treatments included urea ammonium nitrate (UAN) applied at rates of 0, 22.4, 44.8 or 67.2 kg N ha-1 and ammonium thiosulfate (ATS) applied at rates of 16.8 or 33.6 kg S ha-1. A double shear box apparatus instrumented with a load cell measured the energy required to cut wheat straw. Photomicrography and image analysis software were used to measure the cross-sectional area of each individual wheat straw after shearing and these data were used to calculate shear stress and specific energy parameters. Total C and N content was measured for bulk wheat straw samples from each plot. Differences among treatments were often observed, however, few site years had significant differences in wheat straw decomposition indicators as compared to the no-fertilizer control. For example, fertilizer rate and timing of application during summer 2012 and fall 2013 at the Hays site had impacts on wheat straw shear stress at break point. Across site years, earlier (fall) fertilizer application generally resulted in lower remaining residue mass as compared to a spring application. Multivariate and linear regressions suggested that N content and C:N ratio can explain the results observed with respect to treatment effects on winter wheat residue decomposition.