Theses and Dissertations

Issuing Body

Mississippi State University


Walker, Timothy W.

Committee Member

Golden, Bobby R.

Committee Member

Varco, Jac J.

Committee Member

Gore, Jeffrey

Committee Member

Krutz, Jason L.

Date of Degree


Document Type

Graduate Thesis - Open Access



Degree Name

Master of Science (M.S.)


College of Agriculture and Life Sciences


Department of Plant and Soil Sciences


Minimal studies have evaluated nitrification and subsequent denitrification for soils where rice is produced in the delayedlood system. Laboratory and field experiments were conducted at USDA-ARS and the Delta Research and Extension Center in Stoneville, MS to quantify the nitrification potential of southern USA soils, and evaluate nitrogen amendments aimed to reduce nitrification rates on clay soils. The Sharkey clay soil at Stoneville, MS was one of the soils with the greatest nitrification potential. Dicyandiamide (DCD) increased the number of days that half the total recovered inorganic–N was in the ammonium–N form (half-life) by approximately 3old and 18% when compared to non-amended urea in the laboratory and field, respectively. Results suggested that nitrapyrin was not an effective nitrification inhibitor in southern soil. Coated urea (43%N) applied 12 days before flood establishment (dbf) was most successful at reducing nitrification resulting in yield comparable to urea applied one dbf.