Development of urea fertilizers off slow (slow release) had the advantage of Matrix type may increase the uptake of N, N nutrition, meets the needs of and improve soil fertility. Study on organic materials used for modifying urea is carbon. Urea matrix carbon can improve the effectiveness of the absorption of nutrients by plants due to its slow-release urea and carbon offsets can save you 30-40%, reduce the loss of nutrients of urea from both the evaporation or leaching by water. This research aims to study the three main factors, namely the influence of temperature and pH against the rate of release of slow release fertilizers urea carbon matrix, and a corresponding kinetic models to describe the events of the release. The research results showed that temperature and pH effect on the rate of slow release fertilizers, fertilizer-releasing urea carbon matrix. At a temperature of 47 ⁰ C and pH 5 had the highest discharge rate. Kinetic model that fits that can describe the event release of fertilizer urea slow release fertilizers, urea kinetic model, namely carbon matrix of order 0. The result is the value of R2 on each variable most approaching 1 (R2>0.98).