Hi Settler, i've just read a book by Alan Titchmarsh, and depending where you live depends on your PH count, he said that the average soil should be a PH of 7 and is a neutral soil most gardens have number between 6-8 that is slightly acid to slightly alkline.the PH is controlled by its calcium content-the higher your number the more alkaline the soil is,mostly in the form of lime.
When your PH number is low the more acid and less lime it has ,when taking your sample dig 4-5 spot of soil from all over your garden, mix together to get a hole garden count-or singles to get garden area's
that's the basic's
hope this help's
windy ;)