Book excerpt: Sunflower is the second most important oil seed crop in the world. Nitrogen is the most of important nutrient for crop production and is required throughout the crop growth period from vegetative stage to subsequent harvesting. One of the main causes of low yield is imbalanced and inadequate supply of nutrients. Proper amount and time of fertilizer application is considered a key to the bumper crop. The most logical approach to increasing N fertilizer use efficiency is to supply nitrogen when it is needed by the crop. Use of optimum amount of fertilizer through a suitable application method at a time when it is most efficiently and effectively utilized is imperative. Plant N use efficiency can be improved by matching application rate and timing with plant demands. This study was proposed to investigate the effect of timing and nitrogen fertilizer application on growth and yield of sunflower.