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Abstract
1. INTRODUCTION
Sugar beet (Beta vulgaris L.) is considered the second source for sugar production in Egypt and in many countries all over the world after sugar cane (Saccharium officinarium L.). It is a vital crop to man as a source of high energy and as an important source of feed to livestock. About 45 percent of sugar in the world is produced from sugar beet. The Egyptian government plan encourages sugar beet growers to increase the cultivated area of sugar beet and consequently the beet sugar factories to minimize the gab between sugar production and consumption which reached to1.2 million ton every year imported from abroad. The total cultivated area of sugar beet in Egypt reached about 180.000* feddan and the total production exceeded 3.47 million-ton of sugar beet roots with an average of 19.31 ton /feddan.
Now, sugar beet crop has an important position in Egyptian winter crops not only in the fertile soils, but also in poor, saline, alkaline and calcareous soils. Whereas, it could be economically grow in the newly reclaimed soils such as present in large area in Kafr El-Sheikh Governorate at the Northern parts of Egypt, sugar beet plant is one of the most tolerant crops to salinity and wide range of climates. So the great importance of sugar beet crop is not only from its ability to grow in the newly reclaimed areas as economic crop, but also for producing higher yield of sugar under these conditions as compared to sugar cane crop .Also sugar beet being often, the most important cash crop in the rotation, it leaves the soil in good conditions for the benefit of the following cereal crops. Moreover, sugar beet is specialized as a short duration crop, where its growth period is about half that of sugar cane. Furthermore, sugar beet requires less water for irrigation.
Nitrogen is considered to be the most important mineral element of those supplied to sugar beet as fertilizer.Over the past 20 years, progress has been made towards optimizing the use of nitrogen through a better understanding of the crops requirement under varying conditions of soils and climates (Van Burg et al., 1983). In Egypt, nitrogen fertilization of sugar beet differ from site to another, the optimum rate of applied nitrogen for maximum root yield varied from (45kgN/feddan to120kg/feddan. (Mahmoud et al. 1990 and Ramadan, 1997). The most remarkable effect of nitrogen fertilizer on sugar beet will be noticeably by improving the leaf canopy, on the other side over use of nitrogen decrease both sugar percentage and juice quality.
Phosphorus is usually the first element needed when virgin soils are brought into intensive farming .Phosphour element comes next to nitrogen as a vital nutrient for plants. It plays as an agent of energy transfer and deficiency of available phosphorus is more likely to limit crop production than any other material except water.
Tthe application of N and P fertilizers, at optimum rate or levels to meet the satisfied requirements of sugar beet. These requirements should be achieved by applying the recommended favorable cultural practices with reducing the environmental pollution by using the biological fertilizers, such as, nitrogen and phosphour bio-fertilizers under the commercially names Rhizobactrine and Phosphorine or others .The role of biofertilizater especially Rhizobactrine contains active biofertilizer nitrogen fixation