Warren Dick from The Ohio State University discusses what gypsum is, its benefits to soil, sources of gypsum, how it can be applied and how often, and how it helps traps phosphate in the field.

Key takeaways:

  • What is gypsum?
    • Soft mineral composed of calcium sulfate dehydrate and water soluble
    • Preserves the nutrient value of manure by “trapping” ammonia as ammonium sulfate in the soil
  • Gypsum is sourced as a by-product or can be mined
    • FGD gypsum
    • Phosphogypsum
    • Titanogypsum
    • Citrogypsum
    • Biotech gypsum (lactic acid production via fermentation)
    • Mined gypsum from natural deposits
  • Benefits
    • Displaces sodium on exchange sites with calcium and sodium can be leached
    • Ca and S source for plant nutrition
    • Source of S and exchangeable Ca to ameliorate subsoil acidity and Al3+ toxicity
    • Flocculates clays to improve soil structure and reclaim sodic and high magnesium soils
    • Forms Ca-humates and CaCO3 formation
    • Helps build organic matter as Ca ties organic matter to clay particles, which are more stable
    • Improves soil and water quality
  • Gypsum research results
    • A paired field study demonstrated the water quality benefits when applying FGD gypsum
    • FGD gypsum improved aggregate stability and increased infiltration
    • FGD application reduced dissolved and total P concentrations
    • FGD gypsum reduced dissolved and total P loads
    • Significant reductions were realized in surface and tile drainage discharge

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