This research deals with the study of sewage sludge used in agriculture, with the aim of providing a suitable solution for the increasing production of this waste and improving soil fertility in a sustainable way. Effects of sewage sludge application to soil at different rates were studied in a semiarid agroecosystem. The experimental design included plots cropped to barley, oat and wheat and amended with sewage sludge thermally dried at rates 5000 (SW 1), 8000 (SW 2) y 12000 (SW 3) kg/ha and were compared to an unamended soil (control) and a soil treated with mineral fertilization (Mineral) with 300 kg/ha of 15-15-15 (N; P; K). In general, fertilization with sewage sludge thermally dried improved crop response, increasing yield with respect to control soil and mineral treatment. No heavy metal pollution was observed in grain or straw. The study of fertilizer efficiency indexes revealed that the use of thermally- dried sewage sludge at high rates achieved more efficient use the applied N.