How Does Fertilizer Work?

Organic fertilizers are derived from plant and animal sources and add ingredients to the soil that make the soil healthy so plants can thrive. As organic fertilizers slowly break down in the soil, they release nitrogen, phosphorus and potassium as well as trace minerals like calcium and boron. These elements are taken up by the roots of the plant and become the building blocks which the plant uses for growth and flower production, much like vitamins provide the conditions for a strong cellular structure in humans.

Chemical fertilizers are used to correct a deficiency in a plant that shows up in uneven growth or yellowing leaves, for example. An organic fertilizer that works slowly cannot provide this element in a way that a plant can consume quickly, so a chemical fertilizer containing only the missing nutrient such as nitrogen is given to the plant.

Fertilizers also contain elements that are important for the strength and viability of the cellular structure in plants. Nitrogen, for example, is a part of the enzymes and amino acids that the plant needs to grow and make new cells. Potassium is an important element because it increases the strength of cellular walls so they cannot burst in extreme temperatures. For example, when a cell wall fails, the moisture in that cell is quickly released and the cell dies.

Fertilizers are not "plant food" but provide what the plant needs on a molecular level in order for the plant to manufacture food for growth as well as flower and seed production. Fertilizers can affect different plants in different ways. For example, a tomato plant needs nitrogen throughout the fruiting process where a potato plant cannot produce tubers, or potatoes, if too much nitrogen is applied even though the two plants are related.