Soil pH calculator: lime and sulfur
Changing soil pH takes more material on clay than on sand, and it happens slowly. This estimates how much ground limestone (to raise pH) or elemental sulfur (to lower it) you need, and tells you when lowering pH isn’t realistic.
Why pH changes slowly
Soil is buffered: clay and organic matter hold large reserves of acidity (or alkalinity) that resist change. That’s why clay needs two or three times as much lime as sand, and why the same amount works slowly.
Lowering pH in alkaline soils is a special case. Many soils in dry regions contain free lime (calcium carbonate), which fizzes in vinegar. Any acid you add, including sulfur as it breaks down, is used up dissolving that lime before the pH moves. Even 1% lime takes well over 100 lb of sulfur per 1,000 ft² just to neutralise. That’s why gardeners in those regions do better choosing plants suited to their soil.
The rates here are typical extension values for the top 6 inches. A lab “lime requirement” or “buffer pH” result is more accurate for your soil when you have one.