I would trust your state extension service to do your soil test in their labs. They do a good job but this time of year it may be a bit of a wait for the results. Farmers have their soil tested in the fall to find out what nutrients to add over winter and during the spring soil prep. So the sooner you get the soil sample in to the lab, the better. And Arlyn is exactly right. As well as the big three, nitrogen, phosphorus and potassium, plants need three other major elements, sulfur, calcium and magnesium. They also need minute amounts of trace elements such as iron, manganese, zinc and copper in order to thrive. Everyone should have their soil tested. In my state it is free to gardeners as the farmers are taxed to pay for all soil tests done in the state. Many states do not charge or if they do charge it is a minimal fee. well worth it. Call your state extension service and ask questions. They are a great friend of the gardener.
