Ko Ko Maung, Bugwood.org
Not all soils have the same ability to produce plant growth. The productive capacity of a soil must be considered in terms of both its fertility and physical condition. Even if the correct nutrients are present, they must be released in a form readily available to the plant. Soil fertility should then be considered as the soil's nutrient-supplying capacity, and not strictly as the amount of any one nutrient. Therefore, maintaining soil fertility involves adjusting the supply of available nutrients to levels conducive to the desired growth.
To determine the fertility of your soil, collect samples on which to have a soil test performed. Obtain a soil test kit from your county extension office. There is a small cost for the kit, which includes soil analysis and fertilizer/lime recommendations for your particular soil. When you submit the soil for analysis, be sure to specify the crop that you intend to grow since nutritional and pH requirements vary somewhat among fruit types.
You will receive a soil test report back from the laboratory. The Penn State report shows phosphate, potassium (also called potash), magnesium, and calcium levels, as well as soil pH. Suggested fertilizer application rates are provided along with the levels. The report has three sections. First, the pH adjustment shows the amount of calcitic limestone (0 to 3 percent Mg) needed to raise the soil pH to the desired level for your particular crop. Second, the magnesium and calcium section shows the amount of Epsom salts (magnesium sulfate) and gypsum (calcium sulfate) needed by the crop. Finally, the plant nutrient needs section indicates the amount of other fertilizer materials to be used. Before planting, fertilize and lime the soil (or acidify it for blueberries) according to the soil test results.