Potassium leaches readily from soil. Calcium in soil is readily revealed by our test. Limestone can correct a calcium deficiency, and will also neutralize soil acidity. A Low magnesium level is usually associated with acidic soil. Other Elements .
Plants require small amounts of other elements including iron, copper, zinc, sulfur, and boron.
Soil tests have been devised for these elements but they are neither quick nor infallible. Iron, copper, and zinc are affected by soil acidity and we can usually infer their availability from the pH test. There is rarely a deficiency of sulfur, while boron deficiency is usually encountered only where soils have a pH over 7.0. Measurements of soluble salts are sometimes reported on our tests. Overfertilization, salt water, or road salt are often sources of salt.