Soil testing kits?
 

Does anybody use do-it-yourself soil testing? I mean the comprehensive
sort that have tests for pH, and N, P and K at the very least. What kit
did you use? Was it any good?

I am mainly concerned with the accuracy of results, I don't mind if I
need to go to some trouble to get good results but I don't want to waste
time and money (and possibly do harm) "correcting" problems that are not
there.

David