Effect of different planting proportions and nitrogen fertilizer in intercropping forage sorghum and lima bean

In order to study the effect of intercropping on forage yield of sorghum and yield components of lima bean at different planting proportions and nitrogen fertilizer levels, an experiment was conducted at the research farm of University of Tehran in the year of 2010. This experiment was arranged in a split plot design with four replications. The main factor consisted of four nitrogen application treatments, and second factor consisted of seven different planting proportions including pure stands of each crop with replacement and additive series. Quantitative attributes such as dry weights of sorghum, yield and yield component of lima bean were measured in two sampling during growth season. The highest fresh and dry weight of sorghum fodder belonged to additive proportions of sorghum. Nitrogen application treatments had significant effect on sorghum total dry matter of fodder (160 urea kgha-1) and total yield of lima bean (80 urea kha-1) seed. Evaluation of Land Equivalent Ratio (LER) indicated that the highest LER obtained in the combination of 100% sorghum and 20% lima bean which indicates the advantage of intercropping (LER = 1.25).   Key words: Intercropping, additive series, replacement series, land equivalent ratio.