The purpose of this research was to evaluate the yield of T. laxum pasture under five doses of nitrogen (N), phosphorous (P) and potassium(K). This experiment was developed at Experimental Station “Alfredo Volio Mata” of the University of Costa Rica, located at 1542 masl during the rainy season (May), in aplantation of Trypsacum laxum established in 2006. The experimental material was cut at the ground level and harvested 120 days later for the evaluation. The experimental design was of randomized blocks with four repetitions and15 treatments in a factorial response surface 53. The dry andfresh matter yield showed important differences (P<0.05) among the levels of N, P, K, and with 88.6 kg/ha/year of K(28 783 kg/ha/re-growth). The highest production of fresh material was obtained with 130 kg N/ha/year (26 869 kg/ha/re-growth), and with the addition of P the yield showed a linear increment. The highest values for dry matter were 4579 and 4588 kg/ha/re-growth, obtained with 105.6 and 68.35 kg/ha/year of N and K respectively; with P, Trypsacum showed the same tendency as fresh material. The NPK dose that yielded best result was 337 kg N/ha/year, 90 kg P/ha/year and 75 kg K/ha/year.
Keywords: Pastures, NPK fertilization, Guatemala grass, roughage Prodigio.