Chemical fertilizers are plant foods that accelerate the absorption rate of natural ingredients through processing. Common household chemical fertilizers include brands such as Miracle Grow, Nutrigrow and Turf Builder. Always avoid using chemical fertilizers on young plants, as they can cause salt burn.
Nitrogen is the base nutrient found in all chemical fertilizers. Anhydrous ammonia is the most common form. It is taken directly from the atmosphere and condensed with hydrogen and a catalyst to produce NH3. Another common nitrogen chemical fertilizer is aqua ammonia, which is ammonia dissolved in water. This chemical fertilizer requires specific application through injection into the soil. Citrus and tropical plants require fertilizers that are high in nitrogen because they deplete the soil's natural nitrogen so quickly during growing season.
Phosphate is made by milling phosphorus mineral to less than 200 mesh in size. It is then treated with sulphuric acid to weaken its bonds and allow absorption that is more efficient. Regardless of these measures, phosphate will not absorb properly into plants unless the soil is acidic. According to the California Foundation for Agriculture in the Classroom, "Phosphorus, one of the 17 chemical elements required for plant growth and reproduction, is often referred to as the 'energizer' since it helps store and transfer energy during photosynthesis. It is also part of the genetic material of all cells—DNA and RNA." Plants with a single growing season, such as vegetables and annual flowers, especially benefit from a fertilizer high in phosphate.
Potash is mined as either sulphate, salt of chloride or nitrate and then treated through a chemical separation process known as selective flotation. Potash is occasionally also found as natural brine. According to the California Foundation for Agriculture in the Classroom, "Studies have shown that adequate amounts of potassium may promote the growth of long, strong cotton fibers; increase the shelf life of fruits; increase the stem length and quantity of roses; enhance the green color and growth of turf grass; and increase the size and quality of fruits, grains, and vegetables." Plant that are especially high in carbohydrates, such as potatoes, require especially high amounts of potash in their fertilizer.