During a recent workshop, a speaker talked about calcareous soil. He mentioned that calcareous areas have an abundance of calcium. That didn't sound right to me, since I remember from soils class that calcareous meant the presence of calcium carbonate, not calcium.
From Dr. John Sawyer, Iowa State University, calcareous soils:
- have a pH of 7.2 to 8.5
- contain various amounts of solid calcium carbonate (1 to 20% CaCO3 by weight)
- CaCO3 controls soil pH
- CaCO3 (solid) + 2 H+ = Ca+2 + CO2 + H2O
If calcium carbonate is present (as a solid), then how much soluble (i.e. plant available) calcium is there? I don't know, but will be working to find out. It seems to me, that it would be conceivable to need more calcium for plant growth & development, even though the pH is above neutral.
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