Soil pH also influences the effects on the activity of beneficial microorganisms. In strong acid soils, bacteria cannot breakdown organic matter, thus allowing the organic matter to accumulate to high levels, which then ties up the nitrogen that is contained within it. Areas that receive heavy rainfall tend to have acidic soils and light rainfall areas tend to have and alkaline soil. One key ingredient used to decrease acid levels is lime, which counteracts the acidifying nature of fertilizers and rainfall. It is added to increase your pH and also has the advantage of adding calcium and magnesium to the soil.
Sulfur decreases alkalinity and is used less often because soils tend to be acidic more often.
The plants you are going to grow in containers pre-determine the type of soilless media you should use. Acid loving plants should be grown in a media that has a low pH level and alkaline lovers in a high pH mix. Levels can change during the course of the growing season and there are ways to correct pH in containers. Chemical fertilizers, except calcium nitrate, lower the pH of a soil by producing acids as they decompose. Calcium Nitrate, a form of nitrogen found in some fertilizers, is used to mitigate the effects of soil acidity, so your readings will determine which fertilizer you will be using at any given time.