The real neutralizing power of a liming material — it tells you how many tons of YOUR lime to spread to hit a recommendation written in 'lb CCE per acre'.
CCE (Calcium Carbonate Equivalent) is a liming material's purity versus pure calcium carbonate. ECCE (Effective CCE) goes further and folds in fineness — how finely ground the lime is, which controls how fast it reacts in the soil. A coarse, low-purity lime might have an ECCE of 60%; a fine, high-purity lime can exceed 90%.
A lime recommendation is usually written as pounds of pure CCE (or tons of CaCO₃-equivalent) per acre. To get the actual tons of your product to spread, you divide by your material's ECCE. Skip this step and you'll under- or over-lime.
Related: Lime requirement · Buffer pH