Sewage sludge contains high contents of essential elements. Due to such characteristics it may be used in agriculture to improve soil fertility. A field experiment was conducted to study the grain production and mineral composition, as well as the sludge dose for maximum agronomic efficiency, of corn plants grown on a soil amended with sewage sludge from "Companhia Pernambucana de Saneamento (COMPESA), Pernambuco state, Brazil. Sewage sludge was applied at six rates: 0, 7.7, 15.4, 29.7, 45.1, and 60.5 t ha-1 on an Ultisol. The results showed that the sludge amendments significantly increased grain production, the application of 26 t ha-1 being required to reach maximum yield production of corn grains. Such sludge dose was effective for increasing Ca, Mg, Cu, Mn and Zn concentrations in the corn leaves to adequate nutritional levels. Despite the concentrations of N and Fe in leaves increased by sludge application, they were below the adequate level for plant nutrition. Phosphorus and potassium concentrations in leaves were unaffected by sewage sludge doses.
sewage sludge; biosolid; nutrients absorption; Zea mays L
