soil samples may always be used
take a 1/4 to 1/2 inch by a few feet long copper pipe and hammer into the ground of grow as deep as want to be tested then pull out pipe and push dowl rod through the pipe to push out soil and you can test what inch layer you want the dirt ant the bottom of the pipe will be from the deepest and the stuff crammed at the top will be from the top soil but point is you can check dif layers by what 1/2 inch you choose from
mix alittle of all soil to get an average you can be as simple or as particular as you wish w/ this method
