What is Ph and why should I care about it? Our body has an ideal Ph and in fact we can not vary from the ideal very much or we would die. The soil has a ph and plants perform best when it is a certain range . Ph is a way of expressing the acidity or the alkalinity of something. It has a value between 1 and 14 with 1 being the most acid and 14 being the most alkaline and 7 being neutral. with the exception of a few acid loving plants like blueberries and azaleas most plants do there best in a Ph of 6.5 just on the acid side of neutral. In Georgia where I live our soils are naturally acid around 5 to 5.5 and we want to raise that to 6.5 in our vegetable gardens to be the most successful. Basically nutrients are more available to the plant at the right Ph. A lot of times adding good compost to the soil will help balance the Ph but mostly we need to add limestone. Other base materials like potassium raise ph as well but I find it less expensive to use a finely ground limestone. Limestone is a natural rock found in many parts of the country and is considered organic.
To determine if and how much limestone you need you first need to do a soil test. You do this by taking several core samples of soil 4 to 6 inches deep all over your garden and mixing these cores of soil together to get a random sample. If there is one area in your garden that you know have been treated differently in the amount of compost or other amendments that you have already added then you may want to do those separately. You can send your soil sample off to a lab to get it tested. Most counties have a university extension service that can send off your sample to get it tested . There are also some private labs that will test your soil as well. Once you get the results back it will usually come with a recommendation on how much lime or other amendments you need to balance your soil correctly.
It takes a lot of lime to move the ph one point. Approximately 50 pounds per 100 square feet or more. It also takes time to correct Ph. Applying lime several months ahead of the crops you want to grow is the best practice. Tilling lime into the soil will distribute it better than laying on top of the soil but spreading it on the top of the soil will also work.