Chemical fertilizers are made from ingredients that are not organic. Instead, they are created by a chemical process that varies among the types of chemical fertilizer. Many include some proportion of the three major nutrients needed for plant growth: nitrogen, phosphorus, and potassium.
There are a number of different types of chemical fertilizer, all manufactured for applications in different soil conditions for a variety of plants and crops. Most contain significant amounts of the three nutrients known as macronutrients. If the soil lacks any of these three nutrients, plant growth and production will suffer. Due to different planting mediums and soil conditions, chemical fertilizers are often created with this in mind.
Most brands are labeled with three numbers, such as 10-20-30. These numbers refer to the nitrogen (N), phosphorus (P), and potassium (K) content of the fertilizer. What has to be added to the soil often dictates what type of chemical fertilizer is best. For example, soil low in nitrogen will take a fertilizer where the first number is the highest, indicating it is high in nitrogen content. A complete chemical fertilizer contains a percentage of all three macronutrients.
Some chemical fertilizers contain nutrients in addition to the three main types. Ammonia and urea are common additions to chemical fertilizers. Occasionally, there can be a need for fertilizers that add copper, iron, sulfur, zinc, and manganese to the soil. These nutrients are usually present in a smaller percentage than the macronutrients, and are known as micronutrients. They are also necessary for the healthy growth of plants, but in smaller quantities.
Nitrogenous fertilizers are so named because other chemicals are combined with the nitrogen element of the compound. Ammonia, urea, and sodium are all common combinations. Similarly, phosphorus fertilizers have other nutrients combined with the phosphate element. Chemical fertilizers that have salts or chloride combined with a high percentage of potassium are known as potash. These types of fertilizers should be applied carefully, as it is easy to raise the potassium content of the soil too high.
Chemical fertilizers are typically available in three different forms. Liquid forms are often created in a concentrate mixed with water before being applied. Granular forms may or may not be water soluble, and are often time-release fertilizers that only need to be applied occasionally. Powder forms have grains that are much smaller than granular types, and are much more convenient to dissolve in water.