Probing the soil for a soil test.

Robin asked me to write about soil pH.

Soil acidity or alkalinity is measured by pH. This test is done on soil either on site with a test kit or by a laboratory. This one factor is the foundation of soil nutrient reaction. In other words, it affects the availability of other soil nutrients essential for good plant growth.

Robin was concerned about the water pH and the buffer pH on his soil test. The water pH is the measure of the soil acidity or alkalinity. This measure of the soil solution is considered the one that affects plant growth. Buffer pH is a laboratory generated pH. This pH is done to make lime recommendations and has no other practical value.

A pH scale goes from 0 to 14. A pH below 7 is considered acid, and a pH above 7 is considered alkaline. A ph of 7 is neutral. Most plants respond well with a soil pH between 6 and 7. However, plants like blueberries prefer acid soils in the range of 4.5 to 5.5. There are also plants that will tolerate alkaline soil. The pH scale is logarithmic, which means that slight changes in the soil pH will have large effects on plant growth and nutrients availability.

This is the reason everyone is telling you to have your soil tested. You can be a great gardener; but if your soil conditions are not right, your plants will struggle. Soil pH can be adjusted with the addition of lime; this material will help neutralize the soil. In the case of blueberries, when we want a more acid soil, we add elemental sulfur to make the soil more acid.

So, have your soil tested so that you know the pH of the soil in your garden or lawn. This knowledge will help you make decisions that result in great plants.