Manganese can do soybeans a lot of good in many situations, according to field projects and trials by DuPont Pioneer agronomists. Here's a brief summary of what area agronomist Keith Diedrick has found.

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  • Soybeans are more often deficient in manganese than in other micronutrients, and respond well to manganese fertilizers when deficient.
  • Manganese is more likely to be deficient in sandy soils, dry soils, high organic matter soils, and soils with high pH levels.
  • Fields with manganese deficiency are seldom affected uniformly. Manganese deficiency symptoms may also vary from field to field, and are strongly tied to soil properties.
  • Plant tissue analysis is the best tool for confirming a manganese deficiency. Randomly select a number of plants, picking the youngest fully-opened trifoliate from each.
  • To correct manganese deficiencies, a number of manganese sources may be used, with preference to chelated forms of manganese (as opposed to salt forms) supplied by foliar application.
  • To avoid weed control efficacy and nutrient absorption issues when tankmixing with glyphosate:
    • Use the label-recommended rate of spray-grade ammonium sulfate (usually 8.5 to 17 lb per 100 gallons) in the carrier, and
    • Add the products in the correct order: 1) water, 2) AMS, 3) glyphosate, 4) chelated manganese (EDTA preferred).