Soil testing is a useful tool that can help ensure the efficient use of applied plant nutrients.
Soil tests provide a means for assessing the fertility status of a soil, but soil tests do not provide a direct measure of the actual quantity of plant available nutrients in the soil. Instead, soil tests measure the quantity of a nutrient element that is extractable from a soil by a particular chemical extracting solution. The measured quantity of extractable nutrient in a soil is then used to predict the crop yield response to application of the nutrient as fertilizer, manure, or other amendment. As soil test levels increase for a particular nutrient, the expected crop yield response to additions of that nutrient decreases. Over the years, many different soil testing procedures and extracting solutions have been evaluated in an effort to identify the method that provides the most reliable prediction of crop yield response to nutrient application.