Fertilizers are provided to help plants to promote plant growth. Application is usually directly to the soil, for uptake by plant roots, or by foliar feeding, for uptake through leaves. Fertilizers compounds are composed of organic matter or simple chemicals (inorganic). Organic and inorganic fertilizers are used to address soil nutrient deficiencies.
Fertilizers provide in varying proportions the elements nitrogen (N), phosphorus (P), and potassium (K). These along with calcium, magnesium and sulfur are commonly referred to as "macronutrients". Macronutrients are consumed in large quantities by plants. NPK are the primary macronutrients and compose NPK fertilizers. Calcium, magnesium, and sulfur are provided to plants via the application of manure and lime (lime is actually more accurately classified as a "soil amendment".)
To a much lesser degree, plants need boron, manganese, iron, zinc, copper, molybdenum, nickel and chlorine. These are referred to as "micronutrients". Most Minnesota soils naturally contain sufficient amounts of micronutrients for good plant growth.
Although lime supplies the macronutrient calcium as a fertilizer, its primary use is to adjust the acidity of the soil. Crushed limestone (a good source of lime) can be used to raise the pH or alkalinity of soil if its too acidic for good plant growth. Other materials can be used to lower the soil alkalinity if the pH is too high.
Here you will learn about the Minnesota Department of Agriculture's programs that regulate the use, storage, management, and licensing of fertilizers and soil/plant amendments.