This is due mainly to the limestone parent material from which the soils were formed. In addition, home builders may remove topsoil during construction and replace it with more alkaline subsoil. If your soil is alkaline, you can lower your soil's pH or make it more acidic by using several products. These include sphagnum peat, elemental sulfur, aluminum sulfate, iron sulfate, acidifying nitrogen, and organic mulches. An excellent way to lower the pH of small beds or garden areas is the addition of sphagnum peat.
Sphagnum peat is also a good source of organic matter.
On small garden plots, add a one to two inch layer of sphagnum peat and work it into the top 8 to 12 inches of soil before planting. The addition of sphagnum peat to large areas would be cost prohibitive. Granular sulfur is the safest, least expensive but slowest acting product to use when attempting to lower your soil's pH. The table below shows the pounds of sulfur needed per 100 square feet to lower the pH to 6.0 in the top 6 inches of soil. Wait at least 3 months to make another application. Aluminum sulfate and iron sulfate react more quickly with the soil than elemental sulfur.