ISSUE #489

489 - Managing Fields In 2007 After Unharvested Beets

10-17-06

The 2006 crop has exceeded everyone's yield expectations and quality will also be above average. When sugarbeets are left unharvested in some fields potential management concerns for crop production on those fields in 2007 should be considered. It is unlikely that serious production problems should arise for any crop in 2007. However the following information may provide answers to maximize yield of crops planted on fields or parts of fields with abandoned beets in 2006.

General Considerations

  • Determine if abandoned acreage is large enough to justify separate management practices in 2007.
  • Till the crop under ASAP, chop up beets as thoroughly as you can e.g. double disking.
  • Make a map of abandonment areas for future reference.
  • Complete as much seedbed preparation as possible for the 2007 crop this fall.

Fertility Management

Nitrogen

  • Flail shredding or defoliation of tops will accelerate release of N for subsequent crops
  • Fall 2006 soil testing will not give an accurate index of nitrogen availability.
  • Use 2006 beet field satellite imagery for N credits for the 2007 crop.
  • N in the tops will be available very early in the spring of 2007.
  • Each ton of roots with yellow tops will tie up about 5-6 lbs per acre of soil nitrogen.
  • Each ton of roots with green tops will tie up about 2 lbs per acre of nitrogen.
  • Spring applied N for the 2007 crop after abandoned beets will be used more effectively.
  • Apply N fertilizer as close to planting as possible in 2007 to reduce nitrogen immobilization as abandoned beets decompose.
  • Banded N for 2007 row crops will be more effective than broadcast nitrogen.
  • Side dress part of the nitrogen in 2007 after crop emergence to maximize N use efficiency for long season crops like corn.

Potassium

  • Incorporation of sugarbeet roots and tops usually increases the content of available K in the soil.
  • No additional K fertilizer should be required - follow normal soil test recommendations.

Phosphorus and Sulfur

  • P deficiency might occur on fields testing low or very low for P.
  • Use past P soil test data on abandoned beet fields to fertilize for 2007.
  • Consider applying additional P fertilizer for crops with high demand like soybeans.
  • Banded applications of P in the spring will be most effective for 2007 crops.
  • 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.

Diseases

  • Incorporating sugarbeet roots is likely to increase root rot inoculum levels in that part of the field where root rot was present when abandoned.
  • Plant small grains to reduce disease buildup following abandonment.
  • If abandoning beets from a field with an Aphanomyces history be sure to use an Aphanomyces tolerant variety and Tachigaren the next time beets are planted.
  • If abandoning a field with Rhizoctonia present, consider small grains for 2007 instead of beans, corn or potato that build up Rhizoctonia inoculum.
  • Be sure to use a Rhizomania resistant variety in fields with 2006 abandoned beets the next time it's planted to sugarbeet.

Crop Rotation Concerns

  • Plant soybean after abandoned beets to avoid N management concerns in 2007.
  • Limited soil profile recharge of available water may impact early season crops less than long season crops (corn or beans), if rainfall is below average in 2007.
  • Careful spring tillage may be required to maximize stand establishment.
  • If seedbeds are poor consider increasing seeding rates by 10% after abandoned beets to overcome stand establishment problems with small grains, corn or soybean.
  • Soil sample parts of fields where beets were abandoned in 2006 separately from the rest of the field in the fall of 2007, nutrient differences are likely to occur.
  • N management to achieve malting barley quality will be more challenging on areas of fields where beets were abandoned in 2006.

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