Fertilizer adds nutrients and texture to soil that needs to provide nutrients to trees, vegetables, herbs, shrubs and flowers. There are several ways to categorize fertilizer, and the most basic is whether it is organic or inorganic. It also can be classified according to its ingredients, whether it is solid or liquid and by its particular actions, such as slow-release fertilizers that dissolve and release their nutrients slowly. The choice of fertilizer that is used typically depends on the nature of the soil, such as whether it is acidic or alkaline; sandy, clay or rocky; and weak or rich.
Organic fertilizer is all natural and includes things such as bat guano, compost, peat moss, wood ash and manure. These are general soil amendments. They don't burn or harm plants, and they can have long-term positive effects on the soil without damaging groundwater. Organic fertilizer, however, generally has lower nutrient concentrations than inorganic fertilizers.
Inorganic fertilizer is man-made and typically comes as a powder, pellets, granules or a liquid. Examples of inorganic fertilizers are chemical additives that are designed for plants to directly absorb, such as nitrogen (N), phosphorus (P) and potassium (K). These three essential elemental nutrients should naturally occur in healthy soil, but some plants require more of them. Other chemicals that might be included in inorganic fertilizers include calcium, sulfur, iron, zinc and magnesium.
Most inorganic, concentrated fertilizer is rated based on the percentage of nitrogen, phosphorous and potassium, using a rubric called NPK. The amount of nitrogen will encourage growth of stems and leaves by promoting protein and chlorophyll. More flowers, larger fruits and healthier roots and tubers will result from added phosphorus, which also helps plants resist certain diseases. Finally, potassium thickens stems and leaves by fostering protein development. This means, for example, that vegetables would do better with an NPK ratio that is different from what is best for roses or orange trees.
Acidic or Alkaline Soil
Different plants will require soil that has different potenz hydrogen (pH) levels, which are measurements of how acidic or alkaline the soil is. To nudge soil's pH toward the acidic side, inorganic fertilizer such as aluminum sulfate or ammonium sulfate could be used. Lime changes the soil's chemistry to make it more alkaline. Sometimes blood meal or other organic matter can also affect acid levels in the soil.