Effect of different previous crops and nitrogen rate on grain sorghum (Sorghum bicolor L. Moench)

The effect of previous crops (wheat, barley, lentil, Hungarian vetch and winter fallow) and different nitrogen rates (0, 120, 160, 200 and 240 kg N ha(-1)) on grain yield and yield components of grain sorghum (Sorghum bicolor L. Moench.) were examined under irrigated conditions in Diyarbakir, Turkey (subtropic) in 1999-2000, 2000-2001 growing seasons. Grain sorghum was grown in summers and wheat, barley, lentil and Hungarian vetch in winters. In the study, sorghum grain yield varied between 6833.8-9796.9 kg ha(-1). It was determined that Hungarian vetch is suitable for previous crop and 160 kg N ha(-1) N rate was the best nitrogen rate in grain sorghum production. According to interaction of previous crop-nitrogen rate, the highest yield was obtained from the subject grown after lentil with 160 kg N ha(-1). Grain sorghum following legumes in rotation did not respond to applications more than 160 kg N ha(-1), while barley-sorghum increased at all levels of N applied. Wheat-sorghum, fallow-sorghum did not respond to application more than 200 kg N ha(-1).