The need for fertilizer materials which provide particular elements to plants over a long period of time is well known. This reduces the expense of numerous applications. In the production of forage from grasses, N is an element which needs to be continually available but is one which is normally rather quickly dissipated. Sulfur‐coated urea (SCU) has given promise as a slow‐release source of N and the need to compare it with other sources of N, such as ammonium nitrate (AN), for various crops has arisen.This investigation was conducted to determine the value of the use of SCU as an alternative to AN in the production of forage from rye (Secale cereale L.) and ryegrass (Lolium multiflorum Lam.). SCU compositions having dissolution rates of 10, 20, and 30% (dissolution in water in 7 days) were applied at annual rates of 100, 200, and 400 kg of N/ha. AN was also used at these same rates of N. AN was tested at one and three times of application. Data was obtained for two seasons with five monthly harvest dates in each season. For the 2‐year period, the highest yield (P < .05) was obtained from AN fertilization at a 400 kg/ha rate of N when three applications were made. The next highest yields were obtained when 400 kg/ha of N was applied as SCU with no difference between the dissolution rates. For the 2‐year period, there was no significant difference in the total recovery of N from forage receiving 400 kg/ha of N from AN and that fertilized with SCU at either the 30 or 30% dissolution rates. Monthly forage yield and N recovery differences among rates and between the fertilizer sources were evident.