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Thesis (M.S.)—University of Nebraska—Lincoln, 1955. Department of Agronomy.


Copyright 1955, the author. Used by permission.


An investigation which attempted to discover the effect of some nitrogen fertilizer materials along with fungus inoculations on the rate of decomposition of surface residues is reported in this paper.

Laboratory studies along with limited field tests have suggested the possibility of accelerating the decomposition of surface residues by the application of water solutions of nitrogen fertilizer.

Ammonium nitrate, urea, and ammonium nitrate-urea have given the best results of the 5 fertilizer materials tested. Ammonium sulfate, generally, had little effect on the rate of decomposition and calcium Cyanamid showed some tendency to retard decomposition of the residue.

For any one of the 3 nitrogen fertilizer materials that gave the best results, a rate of 20 pounds of nitrogen for each ton of surface residue was found to be adequate for rapid decomposition.

Maintenance of surface oil moisture near field capacity appears to be essential for rapid decomposition.

Laboratory studies have shown that the decomposition of unsterilized surface residue was unaffected by the inoculation of the residue with a cellulose decomposing fungus. Sterilized surface residue, however, inoculated with a cellulose decomposing fungus, in general, showed more decomposition than sterilized residue receiving no inoculation. The decomposition of unsterilized surface residue by the natural soil flora alone or with a cellulose decomposing fungus added was greater than the decomposition of sterilized surface residue inoculated with any cellulose decomposing fungus studied.

Advisor: F.L. Duley.