Date of Award


Degree Type


Degree Name



Chemistry and Biochemistry

First Advisor

McKenney, D. J.,


Chemistry, Agricultural.




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.