Improving Nitrogen Use Efficiency for Cereal Production

Abstract Worldwide, nitrogen use efficiency (NUE) for cereal production (wheat, Triticum aestivum L. ; corn, Zea mays L. ; rice, Oryza sativa L. and O. glaberrima Steud. ; barley, Hordeum vulgare L. ; sorghum, Sorghum bicolor (L. ) Moench; millet, Pennisetum glaucum (L. ) R. Br. ; oat, Avena sativa L. ; and rye, Secale cereale L. ) is approximately 33%. The unaccounted 67% represents a 15. 9 billion annual loss of N fertilizer (assuming fertilizer‐soil equilibrium). Loss of fertilizer N results from gaseous plant emission, soil denitrification, surface runoff, volatilization, and leaching. Increased cereal NUE is unlikely, unless a systems approach is implemented that uses varieties with high harvest index, incorporated NH 4 ‐N fertilizer, application of prescribed rates consistent with in‐field variability using sensor‐based systems within production fields, low N rates applied at flowering, and forage production systems. Furthermore, increased cereal NUE must accompany increased yields needed to feed a growing world population that has yet to benefit from the promise of N 2 ‐fixing cereal crops. The Consultative Group on International Agricultural Research (CGIAR) linked with advanced research programs at universities and research institutes is uniquely positioned to refine fertilizer N use in the world via the extension of improved NUE hybrids and cultivars and management practices in both the developed and developing world.