عنوان مقاله [English]
In order to evaluate different sources and rates of nitrogen on dry matter yield, concentration and uptake of primary macronutrients (nitrogen, phosphorous and potassium) in forage sorghum (Hybrid of Speedfeed), three levels of nitrogen (80, 160 and 240 kg N ha-1) from three N sources (urea fertilizer, cattle manure and equal combination of urea fertilizer + cattle manure) and the control (no fertilizer) were compared in a randomized complete block design with three replications at the research farm of Shahrekord University in 2010. Results showed that dry matter, concentration and uptake of nitrogen, concentration and uptake of phosphorous and potassium uptake of aboveground organs, were significantly influenced by N amendment. The greatest nitrogen uptake was gained in 240 kg N ha-1 as urea fertilizer and urea fertilizer + cattle manure, because of their treatments have high nitrogen concentration (17.5 and 15.4 g kg-1, respectively) and dry matter (14.4 and 16.3 Mg ha-1, respectively). The highest dry matter production (15.7 and 16.3 Mg ha-1), phosphorus uptake (32, 34.2 kg ha-1), and potassium uptake (254, 272 kg ha-1) were obtained in 160 and 240 kg N ha-1 as urea fertilizer + cattle manure , respectively. In general, application of 160 kg N ha-1 as integrated fertilizer resulted to improvement the nutrients uptake (phosphorous and potassium) and desirable forage production. Thus, it can help development of sustainable agriculture by decrease the consumption of urea fertilizer.