Prediction of Nitrogen Status of Sugarbeets by Soil Analysis
1975
Giles, J. F. | Reuss, J. O. | Ludwick, A. E.
The production of high sugar yielding crops of sugarbeets (Beta vulgaris L.) is highly dependent on available N. Excessive N fertilization is frequently cited as a cause of low sugar containing beets, which has become a problem in todays beet industry. The objective of this study was to evaluate the usefulness of N soil tests to predict N fertilizer requirements for this crop. Fertilizer trials consisting of 4 N rates (0, 70, 140, and 210 kg N/ha) were conducted on 33 farm sites in central and eastern Colorado over a 2-year period. Soils ranged in texture from sandy loam to clay loam and were generally calcareous at or near the surface having a pH > 7.0. The results show that soil NO₃-N levels measured before planting are useful in estimating the N requirements of the sugarbeet crop. Soil NO₃-N levels were closely correlated with crop yield and sucrose percentage. Regression analysis indicated that yield and recoverable sugar responses to fertilizer N are unlikely when soil NO₃-N levels (0 to 60 cm) are > 130 kg/ha. A linear decrease in sucrose percent resulted from increasing N levels. Soil NO₃-N had a greater effect on sucrose percentage and plant N content than did an equal amount of fertilizer N during both years. An assessment of the NO₃-N content of the soil to at least the 60-cm depth was found to be an adequate index of soil mineral N availability.
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