Soil pH Amendment Calculator
Recommendation
Understanding Soil pH
Soil pH is a measure of the acidity or alkalinity of your soil. It is measured on a scale of 0 to 14, with 7.0 being neutral. Values below 7.0 indicate acidic soil, while values above 7.0 indicate alkaline soil. Most garden plants prefer a pH between 6.0 and 7.0, as this range allows nutrients to be readily available for uptake by roots.
Why Adjust Soil pH?
When soil pH is too high or too low, plants cannot absorb essential nutrients effectively, even if those nutrients are present in the soil. This leads to nutrient deficiencies, poor growth, and lower yields. For example, in acidic soils, aluminum and manganese can become toxic to plants, while in alkaline soils, iron, manganese, and phosphorus become less available.
How to Use This Calculator
To determine the amount of amendment needed, you must first know your current soil pH. This can be determined using a home soil test kit or by sending a soil sample to a local extension service. Once you have your current reading, enter your desired target pH and your soil type. Soil texture matters because clay soils have a higher buffering capacity and require more lime or sulfur to change pH compared to sandy soils.
Applying the Amendments
Lime (Agricultural Limestone): Used to raise pH. It is best applied in the fall because it takes time to react with the soil. Ground limestone is the most common form and is safer to handle than hydrated lime.
Elemental Sulfur: Used to lower pH. Bacteria in the soil convert sulfur to sulfuric acid, which lowers the pH. This process is temperature-dependent and works faster in warm, moist soil. Like lime, sulfur takes time to work, so apply it well before planting.