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633 - Managing Unharvested Beets

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General Production Considerations on Unharvested Sugarbeet Acres

When sugarbeets are left unharvested there are management considerations that should be taken for crop production on those fields for the following year.

  • Make a map of the unharvested areas for future reference.
    • Unharvested areas in a field may justify separate management practices in future years than the rest of the field.
  • Defoliate the sugarbeets.
    • A flail shredder could be used as well.
    • Defoliating/shredding will accelerate the release of nitrogen for the subsequent crop.
  • It is recommended not to till unharvested sugarbeets.
    • Deterioration of the sugarbeet root is enhanced when it is left in the ground surrounded by soil.
    • Not being surrounded by soil creates a dry sugarbeet carcass and greatly increases the time to decay.
    • Tillage will lift the sugarbeet root out of the ground and deposit the root nearly entirely whole on the soil surface.
    • Multiple tillage passes would be required to incorporate, increasing fuel and labor costs.
    • Dried, non-decaying sugarbeet root carcasses on the soil surface become a nuisance for the next crop in rotation.

  • If spring tillage is required, consider ways to maximize stand establishment.
  • If seedbeds are poor consider increasing seeding rates by 10% to overcome potential stand establishment problems with small grains, corn, or soybean.

Fertility Management on Unharvested Acres


  • Defoliation/Flail shredding of tops will accelerate release of nitrogen for subsequent crops.
  • N in the sugarbeet tops will be available very early in the spring.
  • The sugarbeet root material will tie up (immobilize) nitrogen making nitrogen fertility management challenging.
    • Fall soil testing will not give an accurate index of available nitrogen.
    • Spring soil testing would offer a bit more insight than Fall.
    • Soil sample areas where beets were not harvested separately from the rest of the field as available nutrient differences are likely to occur.
  • Additional actual Nitrogen will be needed for all non-legume crops.
    • Each ton of sugarbeet roots with yellow tops will tie up about 5-6 lbs. per acre of soil nitrogen.
    • Each ton of sugarbeet roots with green tops will tie up about 2 lbs. per acre of nitrogen.
  • Plant soybeans on unharvested sugarbeet acres to avoid N management concerns.
  • Spring applied N on unharvested beet acres will be used more effectively than Fall applied N.
  • Apply N fertilizer as close to planting as possible to reduce nitrogen immobilization as unharvested beets decompose.
  • Banded N for row crops will be more effective than broadcast nitrogen.
  • Side dress part of the nitrogen after crop emergence to maximize N use efficiency for long season crops like corn.
  • N management to achieve malting barley quality will be more challenging on areas of fields where beets were left.

Phosphorus and Sulfur

  • P deficiency might occur on fields testing low or very low for phosphorus.
  • Use past P soil test data on unharvested acres to determine fertilization level.
  • Consider applying additional P fertilizer for crops with high demand like soybeans.
  • Banded applications of P in the spring will be most effective.
  • Starter P is recommended where practical to use it.
  • Sulfur deficiency is not very likely but might occur early in the spring and disappear as crops root into subsoil sulfur supplies.


  • Leaving sugarbeet roots and tops shouldn’t alter the content of available K in the soil.
  • No additional K fertilizer should be required - follow normal soil test recommendations


  • If unharvested areas had root disease present, these areas are likely to have increased inoculum levels in that part of the field for future sugarbeet crops.
  • Plant small grains to reduce disease inoculum buildup on unharvested acres.
  • If beets unharvested are in a field with an Aphanomyces history:
    • The next time beets are planted, plant a high tolerant Aphanomyces variety and use Tachigaren up to 45 grams.
  • If beets unharvested are in a field with Rhizoctonia present:
    • Consider small grains instead of beans, corn or potato that build up Rhizoctonia inoculum.
    • The next time beets are planted, plant a variety with high Rhizoctonia tolerance and use Azteroid fungicide in-furrow as well as a Post Rhizoctonia fungicide application.

Crops to Consider on Unharvested Sugarbeet Acres

  • Soybean – 1st choice
    • Soybeans are a legume and will use nitrogen available or make its own supply making them the best choice for Nitrogen management and lowering nitrogen input costs. Consider increasing plant populations by 10% if seedbeds are poor.
  • Edible beans
    • Edible beans are a legume and will use nitrogen available or make its own supply making them another good choice for Nitrogen management and lowering nitrogen input costs. Consider increasing plant populations by 10% if seedbeds are poor.
  • Small grains
    • Small grains will need an extra 30 - 40 lbs. of actual nitrogen added per acre to offset soil nitrogen tied up in soil by the extra sugarbeet organic matter.
  • Sunflowers
    • Sunflowers are a deep-rooted crop that will be less affected by nitrogen immobilization since they are planted later. They may require and extra 30-40 lbs. of nitrogen per acre to maximize yield.
  • Corn
    • Corn following sugarbeets can experience “fallow syndrome” requiring higher amounts of Phosphorous starter fertilizer, 10 gal/a 10-34-0 is the high limit to be placed in-furrow. Corn will need an extra 30-50 lbs. of actual nitrogen. A population increase of 10% is recommended for poor seedbeds conditions.