Nitrogen requirements of grain sorghum (Sorghum bicolor (L.) Moench) under soil moisture stress

Water and fertilizers are the two major agricultural inputs limiting yields in the arid and semi-arid regions of the world. Proper knowledge of their influence on crops should be obtained for appreciable returns. Therefore, a field study was conducted to evaluate the effects of four nitrogen (N) treatments (0, 56, 112, and 168 kg N/ha), two water (M) levels (39 and 58 cm), and two varieties (V) (Funks G-522DR and Conlee Rusler) on dry matter production, total N concentration, and yield of grain sorghum (Sorghum bicolor (L.) Moench). Total N concentration, dry matter, and grain yield were increased by N treatments. Generally, the highest N rate gave the most significant effects; the other rates had statistically the same responses. Varieties were different in their dry matter and grain yields, but had the same total nitrogen contents, as was suggested by the ANOVA and means analysis. There were no detectable interactions among the factors. Moisture had minimal effect on dry matter and grain yields, but influenced total N concentration significantly. Nitrogen contents increased with the higher moisture level.