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.

Recently, I had a question about the water pH and the buffer pH on a soil test. The water pH is the measure of the soil acidity or alkalinity. This measure of the soil solution is considered the one the 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 those plants like blueberries prefer acid soils in the range of 4.5 to 5.5. There are also plants that will tolerate alkaline soil as well. The pH scale is logarithmic which means that slight changes in the soil pH will have large effects on plant growth and nutrients availability.

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 which will help neutralize your 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 and then you will know the pH of the soil in your garden or lawn. This knowledge will help you make decisions to grow great plants.

Source: Ed Billingsley, County Extension Director, Williamson County and Interim County Extension Director, Jackson County, edb@uiuc.edu