pH Soil Amendment Calculator
Use this soil pH calculator to estimate how much lime or sulfur you need to adjust your garden soil pH.
Enter your garden size, current pH, and target pH to get the required amount of amendment.
Shape
Results
Your target pH is higher than current ā we calculate lime to raise pH.
Note: These are estimates based on sandy loam soil. Heavy clay soils may need 1.5x more, sandy soils may need 0.75x less.
Detailed Explanation
šÆ Purpose
This soil pH amendment calculator helps you estimate how much lime or sulfur you need to adjust your garden soil pH. Most vegetables prefer a pH between 6.0 and 7.0.
š How to Use
1. Choose your bed shape and enter dimensions. 2. Enter your current soil pH and your target pH. 3. The calculator will tell you if you need to raise pH (add lime) or lower pH (add sulfur). 4. It will show you the amount needed in pounds.
š¢ Algorithm
To raise pH (make it less acidic): Apply lime (calcium carbonate) To lower pH (make it more acidic): Apply sulfur The amount depends on: - Soil type (sand, loam, clay) - Current pH vs target pH difference - Bed area and depth This calculator uses average loam soil rates. For sandy soil, reduce by 25%; for clay soil, increase by 50%.
š” Why do it this way?
Why should soil pH be between 6.0 and 7.0? pH measures soil acidity (0-14, 7 is neutral). - Too acidic (pH < 6.0): Too much iron, aluminum, and manganese in the soil ā it burns roots, and plants can't absorb phosphorus or calcium, causing yellow leaves. - Too alkaline (pH > 7.0): Iron, zinc, and manganese get locked up ā plants suffer nutrient deficiencies and leaves still turn yellow. - pH 6.0-7.0: Nitrogen, phosphorus, potassium, and micronutrients are all available for plants to absorb ā this is the "golden pH" for most vegetables. Blueberries and azaleas prefer acidic soil (pH 4.5-5.5) ā those are exceptions. š Sources: ā¢ Cornell Cooperative Extension: https://ccetompkins.org/resources/getting-the-most-out-of-your-vegetable-garden-soil-test-report ā¢ Oregon State University Extension: https://extension.oregonstate.edu/catalog/pub/ec1503 ā¢ University of Maryland Extension: https://extension.umd.edu/resource/lead-garden-soils