Ensuring that your soil pH is appropriate for the types of plants you are planting in your garden is an important step to archeiving success with your food production.
Use a DIY Soil Test Kit or send of samples to a state soil-testing lab to find out what you are working with. The following article gives your a great summary of knowledge for working with soil pH and what you need to do to change pH to accommodate your plants.
http://www.motherearthnews.com/organic-gardening/soil-ph-zm0z14amzkin.aspx