الفهرس 
INTRODUCTION
Effect of Nitrogen fertilizers on yield and sugar content of sugar beetOnly 14 pages are availabe for public view
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Abstract
Two field experiments were carried out during the two successive growing seasons of 2001/2002 and 2002/2003 at the Agricultural Experimental Station, Fac. Agric. <U+2013> Mansoura Univ. , which belong to Belkass district Dakahlia governorate, . sugar beet seeds . Four forms of nitrogen fertilizer : (U), Urea ( 46 %N) (UI), Urea + inhibitor (CU), rock phosphate coated urea (37%N) (AN), Ammonium nitrate (33.5%N). Six rates of N : N0 = Control (Without addition) N1= 25 kg N fed1. N2 = 50 kg N fed1. N3 = 75 kg N fed1. N4= 100 kg N fed1.N5=125 kg N fed1. <U+DBC0><U+DC99> The data illustrate that increasing the content of available nitrogen forms (NO3 , NO2 and NH4+, ((ppm) generally in surface and sub surface layers (A, 0 <U+2013> 25 cm and B, 25 <U+2013> 50 cm) of experimental soil (sandy) with increasing N rates up to 125 kg N fed1 after harvesting sugar beet plants in both season. And the highest mean values of available nitrogen forms content (NO3 , NO2 and NH4+,(ppm)) were obtained at the two rates of 100 and 125 kg N fed1. in general. Also it is noticed that increasing the soil content of NO3 than both NO2 and NH4+ under all N rates used in both seasons. <U+DBC0><U+DC99> The general trend is pointed to increasing the content of available nitrogen forms (NO3, NO2 and NH4+, ppm ) in surface and sub surface layers (A, 0 <U+2013> 25 cm and B, 25<U+2013>50 cm) of experimental soil ( sandy ) after harvesting sugar beet plants due to applying N fertilizer in the recommended form of urea + inhibitor in both seasons. <U+DBC0><U+DC99> The general trend is pointed to increasing all forms of available N due to using N fertilizer in the form of urea or urea + inhibitor specially at the two rates of 100 and 125 kg N fed1 Nitrogen rates effect: Adding N rates in both seasons increased dry roots yield , top dry yield, fresh root yield, N uptake by whole plants, Na uptake by whole plants, Juice purity % , sucrose yield and NO3 , NO2 concentration in whole plants. But decreased sucrose % and T. S. S %. Nitrogen Sources Effect : The highest values with urea + inhibitor in 1st season were top dry yield of sugar beet in ton fed1, fresh root yield, dry root yield, N uptake by whole plants and sucrose yield, while the highest values with urea + inhibitor in 2nd season were fresh root yield and Na uptake by whole plants. In general NO3 concentration in tops & roots and whole plants of sugar beet was intermediate but NO2 concentration in all organs was the highest due to applying N fertilizer in the form of urea + inhibitor. Interactions effect : The highest values were recorded at level of 100 kg N fed1 in the form of urea + inhibitor were fresh root yield, dry root yield, Na uptake by whole sugar beet plants, juice purity (%) and sucrose yield. The present study was recommended by: Using the rate of 100 kg N fed1. in the form of urea + inhibitor for fertilizing sugar beet plants under the conditions soil and more studies to superiorities ammonium nitrate in the 2nd season