Nitrogen metabolism of sugar beets: A recurring problem gets a fresh appraisal

Abstract

The sugar beet is the source of 40 per cent of the world's sugar. About onequarter of the sugar requirement of the United States is obtained from the beets grown on 1,600,000 acres of land (1). G. E. Rush (2) delineated three primary factors limiting the level of efficiency attainable in the sugar beet industry: (a) low net extraction of sugar from beets entering our factories; (b) major losses that occur in handling and storing beets; and (c) high spring labor costs on the farm. One reason for low net extraction of sugar has been the use of excessive amounts of nitrogen fertilizer. The application rate of nitrogen fertilizers to sugar beets has greatly increased during the last few decades. Although increased yields follow the use of nitrogen fertilizers, there has been a subsequent decline in beet quality. Processing losses also have increased. The depressing effect of high nitrogen rates on sugar beet quality was reported by Headden as early as 1912 (3). Later studies by Gardner & Robertson (4) also showed that excessive nitrogen reduced the sugar percentage and its purity. These authors estimated that the reduction in sugar percentage was an approximate linear function of nitrate nitrogen in the beets at harvest and that