What is the difference between dolomitic and calcitic lime?

Pulverized limestone is often applied to overly acidic soil to raise pH and restore nutrient availability. Most lawn grasses do best in slightly acidic soil, where nutrients they need stay most available. Normal lawn care and fertilization tend to lower soil pH over time, so you will need to add lime periodically to keep it in a healthy range. However, applying lime unnecessarily can harm grass instead of help. The only way to know for certain if your lawn or garden needs lime, and which kind of lime to use, is by soil testing.

Calcitic limestone contains calcium, but not magnesium.

Dolomitic limestone contains both calcium and magnesium.

Magnesium is an essential plant nutrient, but too much can harm your lawn. Use dolomitic lime to raise pH when a soil test reveals a magnesium deficiency as well.