Effect of Nitrogen Fertilizer and Its Application Efficiency on Two Local Sorghum Cultivars Sorghum bicolor L. Moench

A field experiment was carried out at El-Kod Agricultural Research Station, Abyan Delta, Abyan Governorate during the seasons 2014 and 2015 in soil sandy silt to assess four levels of nitrogen fertilizers (0, 55, 110 and 165 kg N/ha) utilizing urea fertilizer (46% N) on some crop characteristics and efficiency of nitrogen application on two local cultivars of sorghum (Sorghum bicolor L. Moench). Split plot design was applied in four replicates. Fertilizer levels were distributed in main plots whereas, the cultivars in subplots. The results revealed significant differences between cultivars Benny and Saif in all characteristics during the two seasons. Cultivar Benny was significantly superior to cultivar Saif in all crop characteristics, except the length of spike which was significantly superior in Saif cultivar compared to cultivar Benny in both seasons. The increase in nitrogen level led to significant increase in all parameters of crop growth under study in both seasons, where the highest dose of nitrogen (165 kg N/ha) gave highest grain yield (3013 and 3201 kg/ha) in both seasons respectively, while the efficiency of nitrogen utilization declined with increased level of nitrogen application and highest value in nitrogen efficiency (12.78 kg grain/kg N). The interaction between cultivars and nitrogen fertilizer showed significant differences in terms of all studied parameters during both seasons. The cultivar Benny responded to high level of nitrogen (165 kg N/ha) and gave high grain yield (3640 and 3305 kg/ha) in both seasons respectively. The results yielded significant effect for efficiency of nitrogen application on grain yield between the cultivars, the levels of fertilizers and their interaction in the first season whereas, no significant differences were detected in the second season.