Not all soils are created equal. Some, in fact, need a little help. Worn out, old soil that has been used time and time again may be in need of a nutrient boost, while some soil might be too acidic for the taste of certain plants. The application of fertilizer and lime can solve both of these problems.
Fertilizers contain the nutrients essential for healthy plant growth. Nitrogen (N), phosphorous (P) and potash (K) are the key ingredients of all fertilizers. On the side of most fertilizer bags are three numbers, representing N, P and K in that order, by their weight in the material. Fertilizers that have a high proportion of nutrients by weight are called high analysis fertilizers.
Fertilizers contain other nutrients, as well, to complete the nutrient composition of soil. Sulfur (S), magnesium (Mg), boron (B), zinc (Zn) and molybdenum (Mo) are often included. These nutrients are also listed on the fertilizer bag as elements.
Soil tests are often required to test the need of nutrients in the soil, as well as the soil's pH level. Soils with a low pH (between 0 to 7 on the pH scale) are considered acidic, while soils that have a high pH (between 7 and 14) are considered alkaline. Soil tests can be done with a home pH kit, or soil samples can be sent to a university extension office and tested for a small fee.
Acidic soil can be adjusted to a more neutral soil by the addition of lime. Lime adds calcium and magnesium compounds to the soil, which reduces the acidity. Soils that are too acidic will keep nutrients from reaching the root system of a plant.
Different plant varieties require different amounts of fertilizer and soil acidity to grow. Alfalfa grows best at a pH between 6.2 and 7.8 while peanuts grow best at 5.3 to 6.6. Knowing the right soil acidity, as well as the soil's nutrient needs, will inform of the best application method for both fertilizer and lime.