How much lime or sulfur? Rates by soil texture, and why clay needs more
Why texture changes the rate
Soil pH is held in place by the clay and organic matter in the soil, which act as a reservoir of acidity (buffering). A sandy soil has little reservoir, so a small amount of lime moves its pH a long way. A clay or high-organic soil has a large one, and needs several times as much product to move the same distance. That is why a single "pounds per 1,000 square feet" figure on a bag cannot be right for everyone.
The rates this site uses
Pounds per 100 square feet to move the top 6 inches by one pH unit:
| Texture | Ground limestone (raise) | Elemental sulfur (lower) | Counties |
|---|---|---|---|
| sandy | 3 lb (30 lb per 1,000 sq ft) | 1.2 lb (12 lb per 1,000 sq ft) | 329 (11%) |
| loam | 7 lb (70 lb per 1,000 sq ft) | 2.3 lb (23 lb per 1,000 sq ft) | 2,277 (73%) |
| clay | 11.5 lb (115 lb per 1,000 sq ft) | 3.4 lb (34 lb per 1,000 sq ft) | 525 (17%) |
Texture comes from each county's mapped clay percentage: under 10% clay is sandy, 10-27% is loam, over 27% is clay. Where topsoil organic matter is above 5% (256 counties), the county is treated as one class heavier, because organic matter buffers like clay.
Aim for the middle, split big doses
Every county page aims for the middle of a plant's range, not its edge, so the soil does not drift straight back out. Lime above 50 lb, or sulfur above 20 lb, per 1,000 square feet is split into several applications a season apart: large single doses of sulfur can burn roots, and lime takes months to react anyway.
How these rates should be read
These figures match the lime and sulfur tables widely reprinted by US cooperative extension services. They are a starting point for a typical soil of each texture, not a prescription. They have not yet been checked line by line against a single primary extension publication, and pages say so. A lab test that reports buffer pH gives an exact lime requirement for your soil, and should override these numbers whenever you have one.
How often the answer is "do nothing"
For a cool-season lawn, the typical county topsoil is already in range in 1,034 counties, close enough to leave in 348, needs lime in 1,329 and sulfur in 41; in 379 the soil is calcareous and lowering it is not practical (see the calcareous soil guide).