LEAVING UNHARVESTED BEETS IN THE FIELD THIS FALL PRESENTS SOME CHALLENGING MANAGEMENT DECISIONS FOR 2011. Which crop to use in rotation, what type of tillage is best to speed up root degradation, how should the 2011 crop following sugarbeets be fertilized? Reports of small grain yields in past years after unharvested beets indicate no yield loss on many fields, slight to moderate yield loss (up to 5 bushel/acre) on some, and yield loss of 5 to 10 bushels or more on a number of fields.

Why Crop Yield Loss after Beets? 

It's very difficult to accurately document small grain yield loss without a combine yield monitor. Beets left in the field in the past were from the lowest yielding areas of respective fields. Low yield areas may have been due to ditches, depressional areas, along tree belts or beets were growing on less productive soil types in the field. These areas usually experience lower yields of any crop most years.

Tillage for Beets Left in the Soil

Excellent yields in most of the Red River Valley will likely result in leaving some beets in the field again this year. Past tillage in unharvested fields included using field cultivators, chisel plows, disks, and occasionally mold board plows. Each operation costs $5-8 per acre and has its disadvantages. The most successful practice may be no tillage or defoliation. Beets left in the soil more completely deteriorate over winter. Tops rapidly deteriorate without defoliation and will release N and other nutrients by the end of May. Beets left untilled are uniformly distributed across the field too. Tillage operations leave many beets on the soil surface that can plug ditches and culverts if spring flooding occurs. The U of MN has successfully disked and chisel plowed some fields.

Which Crop to Grow After Beets Left in the Field

SOYBEANS - are the ideal crop choice, they have no nitrogen management concerns, emphasize good stand establishment, and yields might decline in a dry year.

CORN - can have significant yield reduction due to the corn following sugarbeet syndrome (CFS), P & N management is critical, you must establish a good stand, yields could be reduced in a dry year.

SMALL GRAINS - must establish a good stand, N immobilization by roots can reduce yields since small grains require almost all their N early in the season. N management is critical, there is less risk of yield reduction in a dry year than with long season crops.

SUNFLOWER - another deep rooted crop that can suffer yield loss in a dry year, less effected by N immobilization since planted later, may require some extra N to maximize yield.

Fertility Management for Crops after Unharvested Beets

Choosing a Starter Fertilizer for Corn after Beets

Other Considerations

• Determine if abandoned acreage is large enough to justify separate management practices for 2011
• Make a map of abandonment areas for future reference
• Fall 2010 soil testing will not give an accurate index of nutrient availability
• Use 2010 beet field satellite imagery for N credits for the 2011 crop
• N in the tops will be available very early in the spring of 2011
• 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
• Apply N fertilizer as close to planting as possible in 2011 to reduce nitrogen immobilization
• Banded N for 2011 will be more effective than broadcast nitrogen
• Sidedress part of the nitrogen in 2011 after crop emergence to maximize use
• Use past P soil test data on fields to fertilize for 2011
• 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 S supplies
• Incorporation of sugarbeet roots and tops usually increases the content of available K in the surface soil.
• Careful spring tillage may be required to maximize stand establishment
• Consider increasing seeding rates by 10 percent after abandoned beets to overcome stand establishment problems with small grains, corn or soybean
• Soil sample parts of fields where beets were abandoned in 2010 separately from the rest of the field in the fall of 2011, nutrient differences are likely.

Help Available

Contact your Agriculturist for assistance with questions on managing beets left in the field.