Effect of Urea, Ammonium Sulphate and Nitrogen Rate on Growth, Yield and Quality of Sugarbeet (Beta vulgaris subsp sacchrifera L.)

Abstract

The study was conducted in the seasons 2014/15 and 2015/16 in the Sugar Research Center-Guneid farm. The objective was to investigate the effect of two nitrogen fertilizer carriers, namely ammonium sulphate (21%N) and urea (46%N); with four nitrogen rates, viz: control (no nitrogen was added), 43 kg N ha-1, 86 kg N ha-1 and 129 kg N ha-1 on sugar beet yield and quality. Soil of the experiment site was cracking heavy clay soils (Vertisols) with low N and organic matter. Sugarbeet cultivar (Lenard) was sown. Treatments were laid in a factorial arrangement randomized complete block design (RCBD) with four replications. Parameters taken were beet root height, thickness, population and tuber yield. Quality of the sugar beet was determined by the parameters brix (total soluble solids), pol (sucrose content), ERS (estimated recoverable sugar) and pulp % of beet. The end product was the sugar yield which was a product of root yield x ERS % beet. Results revealed that there were no significant or consistent differences between the two source of N in beet root height, thickness, population, leaves and tuber yields for the two seasons. Similarly, there were no significant or consistent differences between the two sources of N for the recorded quality parameters. Sugar beet quality recorded significant readings; however, the second season 2015/16 recorded even better results. On the other hand N rates affected sugar beet parameters differently. Tuber yield increased with the increase of N rates significantly up to 86 kg N/ha in the first season and up to 129 kg N /ha in the second season. Quality characters, namely brix% and pol % increased with the lower N rate (43 kg /ha) then decreased with the higher rates. N rates of 86 and 129 kg per hectare have given best tuber and sugar yields. In conclusion, this study shows that it is more useful to apply urea due to its higher N content (46% N). N rates 86 and 129 kg /ha showed similar tuber and sugar yield. It is recommend that 109.5 kg N/ha (100 kg urea/feddan), should be adopted.