Influence of Nitrogen Fertility Level and Topping Method on Yield, Quality, and Storage Losses in Sugarbeets

The recovery of sucrose from sugarbeets (Beta vulgaris L) has decreased in recent years while root yield has increased. Our objective was to determine the effect of N application rate and topping method on root yield and on the factors affecting recovery of sucrose-sucrose content, purity, and storage loss. The effect of five N fertility levels (0, 67, 134, 202, and 269 kg/ha) on sugarbeet root yield, quality (percent sucrose and percent purity) and crown tissue size was investigated from 1975-1977 in 10 field experiments in Colorado, Kansas, and Nebraska. Crown tissue, the portion of the sugarbeet above the lowest leaf scar, increased from 10.64 to 16.0370 of the total root weight as the N application rate increased from 0 to 260 kg/ha. Total root yield increased from 45.2 to 54.4 metric tons/ha over the same N range, but much of the yield increase was due to increase in crown size. Sucrose content and clarified juice purity (CJP) decreased 1.42 and 1.97% units, respectivdy, as the N application went from 0 to 269 kg/ha. The decrease in quality offset the increase in yield so that increasing rates of N had no significant effect upon yield of recoverable sucrose per ha. The extractable sucrose per metric ton of beets was reduced from 144.5 kg/ton for the 67 kg N/ha application to 128.6 kg/ton for the 269 kg N/ha application. Crown removal significantly reduced yield of recoverable sucrose per hectare but only increased extractable sucrose per ton from 136.7 to 140.0 kg/ton. Quality (sucrose and CJP) was improved both by proper topping and by N management, however, N management has a more dramatic effect upon quality. Total sucrose yield is reduced by topping, but not significantly affected by N application rate. Three N fertility levels (0, 134, and 269 kg/ha) and three topping methods (flailed, half-topped, and topped) were evaluated for their effect on sucrose and quality changes in sugarbeet roots during storage in nine experiments. Failed beets had 27.4 and 25.5% less gross sucrose and recoverable sucrose losses than regular topped beets and 17.3 and 15.7y0 less gross suaose and recoverable sucrose lass than half-topped beets. Method of topping had a significant effect upon sucrose losses in beets grown in all Iri levels. Nitrogen application rate had no significant effect upon gross sucrose or recoverable sucrose losses. Beet quality (extractable sucrose per metric ton) was higher in topped beets than flailed beets at harvest, but no difference existed between topping treatments after storage. Sucrose production per acre and beet quality was maximized with the low fertility, flailed treatments before and after storage.