The three main ingredients or macronutrients in fertilizer are nitrogen, phosphorous and potassium. Nitrogen promotes new growth of the green parts of flowers, such as leaves. It is also essential in the process of photosynthesis.
The main nitrogen-based fertilizer is ammonia. Other nitrogen fertilizers include ammonium nitrate and calcium ammonium nitrate.
Phosphorous helps plants develop strong root systems and enhances flowering and fruiting. Phosphorous plays an important role in energy metabolism, respiration, photosynthesis, enzyme regulation and nitrogen fixation.
Potassium, commonly referred to as potash, is needed for the reproduction and optimal development of plants. It improves drought resistance and activates enzymes in plants. It also plays an important role in photosynthesis and protein and starch synthesis. Potash fertilizers include potassium nitrate, potassium sulfate and potassium chloride.
Fertilizers also contain three secondary macronutrients: calcium, magnesium and sulfur. These nutrients are needed for optimum plant growth. They help plants produce improved quantities of fruit, flowers or foliage.
Fertilizers also contain micronutrients or trace elements, which are already found in all soil types. These nutrients are needed in small quantities and can be obtained by recycling organic matter, such as tree leaves. They include iron, zinc, boron, manganese, copper, silicon, vanadium and cobalt.