Determination of Ammoniacal and Urea Nitrogen

Chemical Reactions in Fertilizer Mixtures: Effect of Ammoniation on Urea Component of Superphosphate Mixtures

“…Phosphorus pentoxide and total nitrogen were determined by the volumetric molybdate and Gunning methods, respectively. Urea was determined by the urease method (4,15). Experiments have shown that this method does not distinguish uncombined urea from additive compounds such as CaS04'4C0(NH2)2 (12) or urea phosphate, CO (NH2)2-HsP04.…”

Fertilizers

“…Urea nitrogen in fertilizers is usually determined by difference (total urea and ammoniacal nitrogen minus the ammoniacal nitrogen) (84). Watt and Chrisp (88) developed a spectrophotometric method for urea which is based on the reaction with p-dimethylaminobenzaldehyde in dilute hydrochloric acid solution.…”

Urea-Formaldehyde Fertilizers, Solubility Relationships and Nitrification Characteristics of Urea-Form

“…Percentage reductions in crushing strength of cake attributable to presence of coating agents were largely independent of the curing time. Reducing the particle-size range of fertilizer from [10][11][12][13][14][15][16][17][18][19][20] mesh to 20-35 mesh increased the caking tendency of fertilizer 18% but did not significantly alter the effect of 2% additions of diatomaceous earth. Caking tests conducted with regular-shaped and crushed irregular-shaped granules of 8-16-16 fertilizer indicated that coating agents were substantially more effective in reducing the caking tendency of fertilizer when used with the regular-shaped granules.…”