ABSTRACT
Solid nitrogen fertilizers are ureaform, sulfur-coated urea, isobutylidenediurea, and polymer-coated products. In addition to ureaform other important urea-form aldehyde products include: mixed fertilizers containing methyleneureas generated by in situ condensation of urea-formaldehyde solutions and urea-formaldehyde solutions or suspensions for direct application. As in the use of other types of controlled release nitrogen fertilizers, the manufacturer of mixed fertilizers should make certain that he finds out all he can about the properties of the product he uses, particularly nitrogen availability, and that he gives the customer full value. Preparation of a stable suspension of a ureaform-like product is described in a 1981 patent assigned to W. A. Cleary Chemical Corporation. The urea-formaldehyde system is an extremely versatile one. As indicated previously, one can obtain much more soluble condensates than ureaforms, and these have the attractive feature of offering release over a shorter period.
