Date of Award
Chemistry and Biochemistry
McKenney, D. J.,
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Since cover crops and intercrops are increasingly used to reduce soil erosion, N loss, and to provide efficient N utilization, it is important to evaluate the consequences of crop residues to N cycling processes. The objectives were to determine effects of incorporation of Vicia villosa L., Hairy vetch (HV); Trifolium pratense L., Red clover (RC); Lolium temulentum L., Annual ryegrass (ARG); Phalaris arundinacea L., Reed canarygrass (RCG); and Zea mays L., corn residues on denitrification, dissimilatory nitrate reduction, and N mineralization/immobilization in a Brookston clay loam (Typic Agriaquoll). With anaerobic-only incubation and when soils were not amended with NO$\sb3\sp-$, all residues stimulated denitrification resulting in NO+N$\sb2$O production 2 times greater than that in the control soil. There was no response in NH$\sb4\sp+$ production. The initial addition of NO$\sb3\sp-$ not only increased denitrification losses of NO+N$\sb2$O on average by 55% but also stimulated NH$\sb4\sp+$ production. During a 5-day aerobic and during subsequent anaerobic periods significant mineralization occurred with incorporated HV. Net immobilization was observed in RC, ARG, RCG and corn treatments during the 5-day aerobic phase. The losses of NO+N$\sb2$O increased with the NO$\sb3\sp-$ amendment in all residue treatments, and particularly in legume treatments, amounting to 5 to 7 times that in the control soil. An increase of NH$\sb4\sp+$ production was also obtained in the legume and ARG treatments which had relatively high initial residue N content, but the production of NH$\sb4\sp+$ in RCG and corn which had low initial residue N content did not respond to the NO$\sb3\sp-$ amendment. The quality of the crop residue, rather than only C/N ratio, appears to be the most important factor regulating these microbial processes under otherwise similar conditions. (Abstract shortened by UMI.) Source: Masters Abstracts International, Volume: 32-02, page: 0618. Adviser: D. J. McKenney. Thesis (M.Sc.)--University of Windsor (Canada), 1993.
Wang, Shi Wei., "The effects of crop residues (two legumes, two grasses and corn) on denitrification, dissimilatory nitrate reduction, mineralization and immobilization of nitrogen in soil." (1993). Electronic Theses and Dissertations. 3920.