7Moll R H, Kamprath E J, Jackson W A. Analysis and interpretation of factors which contribute to efficiency of nitrogen utilization. Agron J, 1982, 74: 562–564.
8Muchow R C. Nitrogen utilization efficiency in maize and grain sorghum. Field Crops Res, 1998, 56: 209–216.
9Fallah S, Tadayyon A. Uptake and nitrogen efficiency in forage maize: effects of nitrogen and plant density. Agrociencia-Mexico, 2010, 44: 549–560.
10Abbasi M K, Tahir M M, Sadiq A, Iqbal M, Zafar M. Yield and nitrogen use efficiency of rainfed maize response to splitting and nitrogen rates in Kashmir, Pakistan. Agron J, 2012, 104: 448–457.