ISSUE #387

387 - Best Management Practices For 2000 PIK Acres

9-22-00

American Crystal Sugar Company shareholders have enrolled about 34,000 acres in the USDA PIK program. Several management practices are recommended to minimize impact of incorporation of roots and tops this fall on 2001 crop production. Dr. John Moraghan, NDSU Soil Scientist and Dr. Larry Smith, U of MN Agronomist have conducted several research trials in the 1980’s and 1990’s that support these recommendations. This data can be found in annual Research and Extension reports, or at www.sbreb.org.

USDA/Insurance Concerns and Compliance

  • Be sure your PIK BID has been approved.
  • Designate the location of the acres for PIK.
  • Have the PIK acres yield appraisal completed by your insurance company for proven yield history purposes.

Agronomic Best Management Practice Recommendations

  • Determine if PIK acreage is large enough to justify separate management practices on the field.
  • Till the crop under ASAP – a double disking should work very well – this should minimize tie-up of N by decomposing roots.
  • Flail shredding or rotobeating of tops is optional.
  • Fall soil testing for N is not recommended
  • Use satellite imagery for N credits for 2001 crop management.
  • Small grains or soybeans are ideal crops to plant after PIK beets.
  • Do most of your 2001 seedbed preparation this fall.
  • Soil sample PIK beet parts of fields separately in 2001 for 2002 crops.

Dr. John Moraghan, NDSU Soil Scientist provided the following excellent discussion of fertility management of PIK acres for the 2001 crop.

The incorporation of sugarbeet storage roots under the 2000 PIK program may cause problems related to fertilizer use for the 2001 growing season. Roots on a dry weight basis contain approximately 75% sugar. The soil microbial population will be greatly stimulated as a result of the incorporation of this readily available energy source into the topsoil. As a result, the 2001 crop and the soil microbes will be competing for fertilizer and soil nutrients. The big question is how farmers can change management practices to give the crop plant an edge in this competitive battle. The following discussion concerns availability in the soil during 2001 of nitrogen, phosphorus, sulfur and potassium in PIK acres.

Nitrogen Availability

The incorporated sugarbeet roots (especially with yellow tops) do not contain sufficient nitrogen to meet the requirements of the microbial population stimulated by the addition of sugar to the soil. The microbes will consequently absorb and render unavailable, at least for early season growth, fertilizer and available soil nitrogen in the vicinity of the decomposing root tissue.

A portion of the tied-up nitrogen in the microbial cells (the so-called biomass nitrogen) will eventually be remineralized and made available for plant growth, but our experience is that such release is of little consequence until July of the year after incorporation.

Soil denitrification, the loss of soil nitrate in the gaseous form; can also be stimulated as a result of the buildup in the microbial population. The microbial population can deplete the oxygen level in the vicinity of the root. Denitrifying organisms can then use nitrate instead of oxygen for respiration.

How much soil or fertilizer nitrogen can be tied-up? The answer depends on how nitrogen deficient the sugarbeet plants are at the time of root incorporation. The color of the leaf canopy gives a fairly good measure of the severity of sugarbeet nitrogen deficiency late in the season. Nitrogen fertilizer requirements for 2001 will be affected by the type of leaf canopy at the time of incorporation of the sugarbeet tops and roots.

1. "Yellow" – sugarbeet Canopies: Each ton of wet roots with associated "yellow" leaf canopies has the potential to tie-up during microbial decomposition approximately 5.3 pounds of fertilizer or soil nitrate-N in the zone of decomposition. For example, a 16 ton/acre root crop, if incorporated, could tie-up approximately 85 pounds of such nitrogen. Consequently, growth of non-legume crops in 2001 could be affected by nitrogen deficiency under such conditions. The objective of the producer should be to reduce the likelihood that applied nitrogen fertilizer or soil nitrate-N "fertilizes" the microbes instead of next year’s crop. Some approaches for decreasing the chances that microbial tie-up will cause nitrogen deficiency in the crop after the PIK year include:

  1. Do not apply any nitrogen fertilizer this autumn.
  2. Apply any recommended nitrogen fertilizer close to planting in 2001.
  3. Consider applying part of the nitrogen fertilizer post-emergent in 2001.
  4. Do not apply nitrogen fertilizer broadcast, if practical, band apply all of the pre-plant spring application of nitrogen fertilizer. Because of its banded method of application, use of anhydrous ammonia on PIK acres is an attractive proposition.
  5. Soybeans, with a potential to satisfy its nitrogen requirement largely through biological nitrogen fixation, should be considered as a crop after a PIK year. Banded application of approximately 40 to 50 pounds/acre of fertilizer nitrogen next spring is recommended to prevent early-season nitrogen deficiency in the soybean corp.
  6. Apply more than the recommended amount of nitrogen fertilizer. The disadvantage of this approach is that the likelihood of the occurrence of deep soil nitrate-N in subsequent years will be increased. Deep nitrate-N is the main factor responsible for the production of poor quality storage roots in the Red River Valley.

2. "Dark-Green" or "Green" Sugarbeet Canopies: Storage roots associated with "dark-green" or "green" canopies will tie-up smaller quantities of fertilizer or soil nitrate-N than their "yellow" counterparts. Each ton of storage roots associated with "dark-green" and "green" canopies is likely to tie-up approximately 1.4 and 2.3 pounds of inorganic nitrogen/ton, respectively, during decomposition. This is equivalent to 22 and 37 pounds of fertilizer or inorganic nitrogen for a 16 ton/acre storage-root crop associated with "dark green" or "green" leaf canopies, respectively. This tie-up of soil nitrogen will be compensated to a large extent by abundant nitrogen mineralization during decomposition of the associated leaf canopies. An application of between 30 to 40 pounds of banded fertilizer-N/acre should overcome any early-season nitrogen stress resulting from sugar decomposition.

Phosphorus and Sulfur Availability

The microbes decomposing sugarbeet roots also tie-up soil phosphorus and sulfur. Because of adequate available soil or fertilizer-P in many Red River valley soils, this tie-up of phosphorus is unlikely to detrimentally affect the 2001 crop. Phosphorus deficiency is most likely to develop, at least early in the growing season, when the 2001 crop is grown on "low" or "very low" phosphorus soils and the incorporated sugarbeet roots contain less than 0.1% P. Unlike the situation for root-nitrogen concentration, there is no easy way to estimate the phosphorus concentration of sugarbeet storage roots. Storage roots in the red River Valley vary greatly in phosphorus concentration (from 0.06 to 0.17% P). There is evidence that the decomposing sugarbeet roots can increase the availability to plants of native soil phosphorus. Use past P soil test data to fertilize 2001 crops.

Soils, especially subsoils, in the Red River Valley are generally high in available sulfur. However, some sulfur deficiency may occur during early growth of the 2001 crop as a result of decomposition of storage roots on PIK acres. Such deficiencies are likely to disappear as roots penetrate the subsoil.

Potassium Availability

Incorporation of sugarbeet tops and roots will increase the content of available soil potassium in the topsoil. There is little chance that crops grown on PIK acres in 2001 will require any fertilizer potassium.

"The Sugarbeet Harvest – Reap What You Sow" is a excellent new fact sheet discussing "Gold Standard" harvest objectives of (1) reducing field losses (2) reducing dirt tare (3) proper defoliation (4) delivery of frost free roots (5) and putting beets into long term storage in excellent condition. Contact your agriculturist for a copy of this brochure, or review it under Ag Notes @crystalsugar.com.

Advantage of Tillage on PIK Acres

Immediate incorporation of roots and tops increases K content in the soil.

2000 Grower Idea Contest

Remember to take photos now to document your ideas. Agriculturists have entry forms for the contest.