Soil pH & Lime Amendment Calculator

A lab soil test from your state agricultural extension office is the most reliable - it typically costs $10-20 and includes a buffer pH reading that determines a precise lime rate for your soil. Home pH test kits and meters are faster but less accurate; they are fine for rough planning, but confirm with a lab test before applying a large or expensive lime order.

A simple jar test gives a rough answer: fill a clear jar about a third full of soil, add water to nearly full, shake well, and let it settle for 24 hours. Sand settles first at the bottom, then silt, with clay remaining suspended longest or forming the top layer. If you are between two categories, use loam as a reasonable middle estimate.

Yes. Over-liming pushes soil pH above about 7.5, which locks up iron, manganese, zinc, and other micronutrients even though the soil still tests as having them - symptoms look like a deficiency because functionally it is one. Over-liming is also slow to reverse; lowering pH back down (with sulfur or acidifying fertilizers) takes even longer than raising it did. Retest before adding more lime rather than assuming last year's application wore off.

Dolomitic limestone contains both calcium and magnesium carbonate, while calcitic limestone is almost pure calcium carbonate. Both raise pH at a similar rate per pound; choose dolomitic if your soil test also shows a magnesium deficiency, and calcitic if magnesium is already adequate or high, since dolomitic lime would push magnesium even higher.