ISSUE #502

502  - Crop Production Management After Beets Left In Fields

9-14-07

LEAVING UNHARVESTED BEETS IN THE FIELD THIS FALL PRESENTS SOME challenging management decisions for 2008. Which crop to use in rotation, what type of tillage is best to speed up root degradation, how should the 2008 crop following sugarbeets be fertilized? Reports of small grain yields in 2007 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 small 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 2006 were from the lowest yielding areas of respective fields. Low yields may have been due to ditches, depressional areas along tree belts or beets were growing on less productive soil types in the field.

Tillage for Beets Left in the Soil

Excellent yields in most of the Red River Valley will almost certainly result in leaving some beets in the field again this year. Past tillage in PIK years and 2006 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 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 Field

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

CORN - can have significant yield reductions due to 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

CropFertility Recommendation
Soybean No special management needed
Small Grain Add 25 to 30 lb/acre extra nitrogen to maintain yields
Corn
  • Use an in-row or 2x2 starter fertilizer with P and zinc chelate
  • Add additional broadcast P based on soil test results
  • Select "fallow syndrome" tolerant hybrids if data is available
  • Require 30-50 lb/A extra N to maximize yields

Choosing a Starter Fertilizer for Corn after Beets

Soil Test Level for P or ZnRate of 10-34-0Amount of N-P-K AppliedRate of Zinc Chelate
 Gal/ALb/AQt/A
Low 10 11-39-0 1-2
Medium 7 8-27-0 1
High or Very High 5 6-19-0 1

Other Considerations

  • Determine if abandoned acreage is large enough to justify separate management practices for 2008
  • Make a map of abandonment areas for future reference
  • Fall 2007 soil testing will not give an accurate index of nutrient availability
  • Use 2007 beet field satellite imagery for N credits for the 2008 crop
  • N in the tops will be available very early in the spring of 2008
  • 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 2008 to reduce nitrogen immobilization
  • Banded N for 2007 will be more effective than broadcast nitrogen
  • Sidedress part of the nitrogen in 2008 after crop emergence to maximize use
  • Use past P soil test data on fields to fertilize for 2008
  • 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 2007 separately from the rest of the field in the fall of 2008, nutrient differences are likely.

Contact Your Agriculturist for Assistance

Soil Sample 2006 Beets Left Area

Be sure to soil sample parts of fields with beets left in 2006 separate from harvested areas. Nutrient levels may be higher where beets were left in 2006.

Soil Sample Analysis for 2008

Even though the Northwood Agvise lab was destroyed they will transport samples to their Benson lab for analysis. The NDSU lab can also handle additional samples this fall. Agvise will rebuild at Northwood.