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Maize (Zea mays L.) production in the smallholder farming areas of Zimbabwe is based on both organic and mineral nutrient sources. A study was conducted to determine the effect of composted cattle manure, mineral N fertilizer, and their combinations on NO₃ concentrations in leachate leaving the root zone and to establish N fertilization rates that minimize leaching. Maize was grown for three seasons (1996–1997, 1997–1998, and 1998–1999) in field lysimeters repacked with a coarse‐grained sandy soil (Typic Kandiustalf). Leachate volumes ranged from 480 to 509 mm yr⁻¹ (1395 mm rainfall) in 1996–1997, 296 to 335 mm yr⁻¹ (840 mm rainfall) in 1997–1998, and 606 to 635 mm yr⁻¹ (1387 mm rainfall) in 1998–1999. Mineral N fertilizer, especially the high rate (120 kg N ha⁻¹), and manure plus mineral N fertilizer combinations resulted in high NO₃ leachate concentrations (up to 34 mg N L⁻¹) and NO₃ losses …