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Replant soybeans or leave current stand?

Agronomy Bulletin 49 ─ Soybean Replant Decisions

Situation

Many factors can cause stand reduction in soybeans. Replanting may be one option to consider.

Factors to Consider

  • Cause of stand reduction
  • Replanting date
  • Weed control
  • Yield potential
  • Replanting costs
  • Crop insurance
  • Yield potential of replanted stand
  • Seed availability
 

Action Plan

  1. Identify cause of stand reduction. Before deciding to replant, determine what led to the stand reduction. If the problem cannot be identified or addressed, replanting may result in the same sparse stand. Factors that may reduce stand preemergence are equipment malfunctions, poor seedbed preparation, too much or too little soil moisture, poor-quality seed, soil crusting, disease, insects or herbicide injury. Factors that may reduce stand postemergence are insects, disease, herbicide injury, hail, flooding or animals.
  2. Estimate current viable plant population. If damage has occurred to an existing stand, wait several days to determine if plants are alive and regrow. Sample several random sites across the field to determine population. Some portions of the field may not require replanting. Count soybeans to determine current population (use Table 1), or for drilled soybeans, use the hula hoop method (Table 2).
  3. Estimate yield potential of current stand. Using Table 3, determine expected yield potential of the current stand. Example: A field with 30-inch rows and a current population of 60,000 could still yield 94 percent of normal.
  4. Estimate yield potential due to later planting. Use Table 4 to determine yield potential based on planting date. Example: Soybeans replanted on June 10 are expected to yield 90 percent of normal.
  5. Compare yield potential due to later planting. Compare the yield potential of your current stand to the yield potential of your replant to determine if replanting is warranted. In our examples, a stand of 60,000 from the first planting has more potential — 94 percent — than replanting on June 10 — 90 percent.
  6. Other considerations. Consider other factors such as demands on time, other cropping practices, and pesticide, labor, fuel and seed costs in your replant decision.
 

Summary

When faced with a less-than-desirable soybean stand, analyze the yield potential of the current stand versus a later-planted stand to determine if a replant is warranted. For more information, contact your local Mycogen Seeds commercial agronomist or trusted agronomic adviser.

Published on Monday, June 02, 2014