Melamine/Urea and Oxamide Fertilization of Kentucky Bluegrass

The commercial lawn care industry represents a large market for N sources. A formulated melamine (2,4,6-triamino-s-triazine) plus urea combination (MLU) (45% melamine by weight) and oxamide were evaluated for use by the lawn care industry by comparing turfgrass response from these fertilizers to that from urea, sulfur coated urea (SCU), ureaformaldehyde (Nitroform), and a non-fertilized check. Fertilizers were applied four times per year to field plots of Kentucky bluegrass (Poa pratensis L.) growing on a Flanagan silt loam (fine, montmorillonitic, mesic Aquic Argiudoll) at a rate of 49 kg N ha-1 per application. Color ratings and clipping weights were determined weekly during the growing season. Trends in color ratings paralleled those in clipping weights. During the first year of the study, MLU treated turf received significantly higher color ratings than nonfertilized turf on only 38% of the rating dates; this increased to 76% in the third year of the study. Color ratings for MLU fertilized turf compared more closely to ratings for Nitroform fertilized turf than for ratings for urea or SCU fertilized turf. The turf fertilized with oxamide received higher color ratings than Nitroform or urea fertilized turf and compared favorably with SCU fertilized turf. Programs utilizing MLU would require either high initial application rates or supplemental applications.of another N source to provide acceptable results. Oxamide appeared suitable for use by the lawn care industry