When would you apply lime to a garden soil, and what effect does gypsum have on soil?

• A. Lime raises pH when soil is too acidic; gypsum adds calcium and can improve soil structure and soil sod issues but does not raise pH.
• B. Lime lowers pH; gypsum raises pH and improves soil drainage.
• C. Lime adds calcium and improves soil structure; gypsum lowers pH.
• D. Lime is never used in home gardens; gypsum is used to acidify soil.

Answer: (A)

Managing soil pH and soil structure is the key idea here. Lime is used when the soil is too acidic to raise the pH, which also helps reduce aluminum toxicity and, especially with dolomitic lime, adds calcium (and magnesium). Gypsum, on the other hand, supplies calcium (as calcium sulfate) and can improve soil structure by helping clay particles flocculate, and it can help with sodic soils by displacing sodium. Importantly, gypsum does not raise soil pH.

So in practical terms: apply lime to acidic soils to raise pH and improve nutrient availability; apply gypsum when you need extra calcium and better soil structure or to address sodic soil conditions, without expecting a pH change.