Protecting Soybean Yields

Del Voight- Penn State Extension

Numerous growers question what is the current trends in raising soybeans in Pennsylvania.  One reason I am involved with the Soybean Contest is that as an agronomist we get to view what practices seem to promote these high yields. The Agronomy Guide Soybean Production Section details our current recommendations in detail.  Here are some highlights.

  1. Soil Management(Soil Test not less than 3 years old)
    • Maintain a pH of 6.8 but not higher than 7.2
      • If less than 6.8 utilize .25lb/acre of sodium molybdate either on the seed or applied before V2
      • Inoculate with rhizobium regardless of history.
    • Maintain phosphorus and potassium levels in the optimum range.
    • Check compaction in the spring with a penetrometer and avoid side wall compaction by adjusting planting date so as to ensure soil is dry enough to plant into.
  2. Rotations
    • Rotate with a grass seems to aid in production.  Growers use cover crops of wheat or barley and rotations with corn.
  3. Variety Selection

    • Get to know a variety and what it requires.  Yields can vary 18 bushel per acre within a maturity based on variety.Numerous pest resistance packages are unique to varieities and growers need to make selections based on the field in question and diseases that may be present in the field.
    • Many growers and Penn State research has shown that in many cases early maturing soybeans in the southeast tend to outperform full season with respect to timing grain fill to late season rains.
  4. Seeding Rate
    • Seed drop will vary by soil conditions  and tillage practices.  Tremendous yields are confirmed at seeding rates of 140,000.  To that end I have documented the final stands seem to always end up at about 120,000ppa. The grower needs to make the decision as what rate to drop to acheive a final stand at harvest of 120,000 ppa. In most situations dropping 170-180,000ppa seed drop will meet the needs for full season early to mid season plantings. Late and or double crop plantings should be much higher in the 200-225,000ppa ranges due to the influence of sunlight on the plants ability to gain hieght and flowers later in the season.
  5. Planting Date and Row Width

    • For early planting row width is not important however as planting is delayed into late May the advantage of narrow rows is evident.
    • Extremely early and or extremely late often times results in reduced yields however the wide planting window afforded between those times gives ample time to get the soybeans planted and growing.
  6. Foliar Nutrients
    • Gather leaves at R2 when the plant is at full flower and send to for a plant tissue test. Determine any hidden fertility issues. Select a PDA approved foliar fertilizer or dry application with basic fertilizer to manage any micro nutrient issues.
  7. Pest Management

    • Utilize a seed treatments with an insecticide(imadicloparid, thiomethoxym, or pyrethroid) and fungicide for early planted soybeans and particularly in fields that have a manure history or tend to be moist or in no till conditions.
    • Consider a pre followed by post herbicide program or ensure weeds are controlled by the time the weed height reaches 6 inches in height.
    • Scout for insect pests and treat accordingly
    • Scout for disease at R1 and determine applications of a fungicide at R2 keeping in mind the two week forecast if calling for high humidity and wet conditions.
  8. Harvest Management
    • Harvest beans at 14-16% moisture 
    • Ensure slow speed during combine process ensuring reel speed is managed based on shatter potential which changes daily.
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