الفهرس 
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Abstract
, Rice is considered one of the major food and export crop in Egypt and it is one of the most important and leading cereal crops. Annually, rice is growing in the 1.35 million feddan in Egypt and the total production is about 6 million metric tons The nitrogen deficiency in the Egyptian soils is one of major limiting factor for rice production then nitrogen is essential to the rice plant, with about 75% of leaf N associated with chloroplasts, which are physiologically important in dry matter production through photosynthesis ( Dalling, 1985 ). Rice plants require N during the vegetative stage to promote growth and tillering, which determines the potential number of panicles ( Mae, 1997 Timing of fertilizer application may be the most critical factor in determining fertilizer uptake efficiency and crop yield. This is especially true for nitrogen fertilizer when fertilizer is applied near the time of physiological plant demand, therefore; the plant is able to be more efficiency uses the nutrients. The more nutrients that are used, the less opportunity there will be for loss. So that, it should have to manage the nitrogen fertilizer schedules to best match application with the plant demands. Split application of nitrogen as compared to single application can reduce potential nitrogen losses by up to 30% and reduce potential groundwater contamination. In order to obtain the maximum effect of nitrogen fertilizer it is not only important to resort correct dose of the fertilizer but also to apply it in appropriate time ( Thakur, 1993