Effect of Irrigation Methods and N-applications on the Utilization of Nitrogen by Sugar Beet Grown under Arid Condition

A field experiment was carried out at the Agricultural Experimental Station, Kalapshoo Farm, Fac. of Agric. Mansoura Univ., which belong to Belkass district-Dakahlia Governorate, Egypt during 2006/2007 season. This work aimed to investigate increasing yield and quality of sugar beet crop (Beta vulgaris, L., variety Top) under the conditions of the present zone (arid sol, sandy soil under reclamation where saline soil and water as well as it is situated near the factory of sugar manufacture). Two methods of irrigation (drip & furrow), four N sources (ammonium nitrate, AN ; urea, U ; urea + agrotain inhibitor, UI and coated urea, CU) and N rates (control, 50, 100 and 125 kg N fed-1) were used. The results revealed that, drip irrigation increased significantly fresh, dry (roots & tops) and sugar yields of sugar beet and decreased juice purity but sucrose percentage was not affected. Also, N and Na content of roots and tops and the uptake by whole plants were increased. NO3- concentrated in tops but the opposite trend was found for NO3- in roots and NO2- in both roots and tops. The effect of N sources on mentioned parameters differed significantly but the superiority was to applying urea + agrotain inhibitor and followed by coated urea. Increasing N rates increased the values of these parameters and the superiority was to adding 100 kg N fed-1 except sucrose % was decreased. However the differences reached the level of significance in most cases. Under the present conditions and from the view of saving irrigation water and the high yield and quality of roots, tops and sugar as well as to removing more Na ions, also from view of using roots residues and tops as a fodder for animals or as amendments to reclaim different soil types, the obtained results are recommended by applying 100 kg N fed-1 in the form of urea with inhibitor or coating under drip irrigation method