the effects of different levels of irrigation and nitrogen fertilizer on productivity and efficiency in corn (zea mays l.), sugar beet (beta vulgaris l.) and sesame (sesamum indicum l.)

optimum uses of water and nitrogen resources are the most important factors in agricultural systems due to limitations of agricultural inputs especially water. in order to investigate the effect of different levels of nitrogen fertilizer and irrigation on efficiency and productivity of water consumption in three crop (sugar beet, corn and sesame) an experiment was carried out as strip split plot based on randomized complete block design with three replications at the agricultural research station, ferdowsi university of mashhad during growing season of 2008-2009 .the main, sub and strip factors were three species (sugar beet, corn and sesame), three irrigation levels (100, 75 and 50% of water requirement of each crop) and four nitrogen levels (0, 50, 100 and 150 kg.ha-1), respectively. the result showed that the highest water use efficiency was observed as 2.4, 1.8 and 1.5 kg dm.m-3 in corn, sugar beet and sesame, respectively. the maximum water use productivity was obtained for sugar beet (4200 rails.m-3), sesame (2123 rails.m-3) and then for corn (1768 rails.m-3). interaction effect between water and nitrogen was significant on water use efficiency and productivity for all three studied crops. water use efficiency declined up to 19% by decreasing 25% of water requirement. water use productivity decreased in all three studied crops by increasing nitrogen consumption. it seems that high nitrogen level could not be affect on reducing drought stress effects.