Preceding crops (PC), nitrogen fertilizer (N) and plant density (PD) are management methods that can increase agronomic nitrogen efficiency (ANE) and grain yield of maize. This study, conducted at the farm of the Experimental Research Center, of the Faculty of Agriculture Benha Univ., during 2006 and 2007 seasons. The aim of this investigation was to study the influence of four N rates (0, 40, 80 and 120 kg N/fed ) and three plant density (18000, 24000 and 30000 plant/fed) on ANE and maize yields following wheat and Faba bean. Results indicated that there were significant effects for winter preceding crops on plant height, chlorophyll content (SPAD-units), ear weight, grain yield/fed, grain protein content (GPC) and grain N uptake. Sowing maize after faba bean gave high grain yield and its components. Growth, yield of maize and yield components significantly increased with increasing the rate of N fertilizer up to 120 kg N/fed. Applying N at 40, 80 and 120 kg/fed resulted in ANE of 10.32, 10.49 and 9.92 kg grains/kg N applied in 2006, being 10.2, 8.82 and 7.78 kg grains/kg N in 2007, respectively. Increasing PD from 18000 to 30000 plants/fed delayed tasseling and silking date, but increased plant and ear height and ANE. On the other hand, increasing planting density significantly decreased ear leaf area and most yield components. However, increasing PD did not significantly effect on grain yield in the 2nd season and ANE in the 1st season. The three main factors i.e. preceding winter crops, N rates and planting density positively interacted.
Key words: maize, preceding crops, plant density, N rates, yield and ANE.