Precision “N” Increases Profits

Precision nitrogen application has proven to be a moneymaker for sugarbeet growers in the Red River Valley. A report from American Crystal Sugar Company has shown the advantage of applying nitrogen based on grid or zone soil testing. (See figures) In sugarbeet production, the amount of sugar produced per acre is reduced if excessive nitrogen is applied and yield is reduced if too little nitrogen is applied. By soil testing fields in small grids, by topography, or in zones, the growers are able to apply just enough nitrogen to maximize sugar production.

Satellite images taken in late August of the sugarbeet canopy are used to credit the amount of nitrogen contained in the sugarbeet tops. Most of the nitrogen in the top will be released for the next crop year. Fields are broken into three to five zones based on the color of the sugarbeet canopy (green, yellow-green and yellow). The areas with green tops require low amounts of nitrogen fertilizer the next year because the green canopy will supply up to 100 lbs./acre for the next crop. The areas with yellow tops require a large application of nitrogen because the yellow sugarbeet tops contain very little nitrogen.

Effect of Soil Testing Method on
Sugarbeet Yield and Quality in 1999
American Crystal Sugar Company
Soil Testing
Sugar % SLM % Recoverable
Sugar/Acre lbs
No Soil Test 15.8 17.13 1.47 313 4945
All Methods 19.8 17.38 1.40 320 6336
Grid Tested 21.0 17.27 1.38 318 6678
Zone Tested 21.2 17.38 1.36 320 6784

The second year after sugarbeets, the canopy zones established from the sugarbeet canopy are used to divide the field into zones for soil testing. University research has shown that the areas that had green sugarbeet tops will remain high in soil nitrogen for many years and should be sampled separately. The yellow beet top areas and the yellow-green areas are also sampled as separate zones. Variable rate nitrogen is then applied based on the soil samples from the three zones. Managing nitrogen all through the rotation allows the growers to get the highest recoverable sugar from each acre when sugarbeets are grown every third or fourth year.