Working compost into the soil is almost always necessary. The process of working in compost lets me see into the soil and see how rocky it is and what it might need. I have learned that the eye helps, but the scientists at the soil lab at the Extension Service in Amherst, MA give an excellent breakdown of the soil and what it needs. A test leads to and economical use of soil and amendments and is well worth the money. A full soil including measuring all nutrients, a graphical representation and analysis of the texture and grain size as well as testing for salts and metals, Ph, organic matter etc., cost about $150 with but prevents surprises down the road.