Response of three sugar beet varieties to compost, mineral nitrogen fertilizer and their combination under sandy soil conditions ll- yield and quality

Two field experiments were carried out at the Agricultural Experiments Desert Station Faculty of Agriculture Cairo University in Wadi El-Natroon El-Beheira Governorate during 2008/2009 and 2009/2010 seasons, to study the response of three sugar beet varieties, i.e. KWS1436 Swello and Faraba growing in sandy soil to compost (CM) Mineral-N fertilizer and their combinations, at five treatments 4 tons fed-1 of (CM) 4 tons fed-1 of (CM) +80 kg N fed-1 (100% N) 4 tons fed-1 of (CM) +60 kg N fed-1 (75 % N) 4 tons fed-1 of (CM) + 40 kg N fed-1 (50 %N) and 80 kg N fed-1(100 % N) on yield and quality of sugar beet under drip irrigation system. The obtained results revealed that sugar beet varieties differed significantly in all studied traits in both seasons except for sugar yield, purity % and sugar losses molasses (SLM) % in the 1st season only. KWS1436 variety surpassed the other two varieties in sucrose extractable sugar % as well as sugar yield, also it gave the highest root yield (28.81 ton fed-1) and purity in the 1-1 season. Swello variety recorded the highest root yield (29.96 ton fed-1) in the 2nd season. In combination treatments, increasing N levels from 40 to 80 kg N fed-1 significantly increased top root and sugar yields and sucrose % in the two seasons. Combination of CM + 80 kg N fed-1(100 % N) produced the highest extractable sugar % (15.53 %) in the 1st season and increased root yield by (11.42 and 3.16 % ) sugar yield by (13.62 and 5.22 %) in the 1st and 2nd seasons respectively and sucrose % by (2.08 %) in the 1-1 season as compared with adding 80 kg N fed-1(100% N) alone. Combination of CM + 60 kg N fed-1 increased sucrose % by (4.13 %) as compared with 80 kg N fed-1 alone in the 2nd season. Compost alone ve the highest purity and Alkalinity coefficient (AC) % and the lowest impurities (K Na and Alpha-amino N %) and SLM% in the 2nd season. Various interaction orders among the two factors affected significantly all traits under study. According to this investigation to gain high sugar yield of sugar beet KWS1436 fertilized by 4 tons compost + N level of 80 kg N fed-1 (100% N) is recommended under saline sandy soil conditions of Wadi El-Natroon and similar areas..