Soil tests are not useful for nitrogen as it washes away during the winter, The big three elements are NPK and with nitrogen level not very useful. Phosphorus is next. It is almost poisonous in high levels and I have experienced phosphorus "poisoning " in one garden. So the "P" levels are my most needed information. Next is potassium that is not a problem in high levels and knowing what you have and what to add is useful. For me the sulfur level is next as we have low sulfur in our soil. Next is magnesium, needed for lots of things and green leaves. The rest of the elements are less useful information and boron is one that you do not generally want to add even if it is low. It goes from needed to poisonous with very slight amounts. After the phosphorus levels, the pH is the next most important data and they will recommend treatment. For us it will always be we have acid soil and how acid is the answer. Whether to use dolomite lime and how much is in the recommendations. If you have alkaline soil , they will recommend sulfur or maybe ammonium sulfate. All of this ignores organic gardening but you can ask for an organic matter percentage. Dahlias are just another crop to the soil test people and they assume, probably correctly, that soil test data applies to almost any similar crop.
