Difference Between Inorganic & Organic Fertilizer

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Using the correct fertilizer is the difference between whether your plants live or die. Plants need 18 different nutrients in order to grow, live and produce their flowers and fruits. They absorb three of these nutrients through the air and water while the other 15 are gained through the soil. When the soil does not offer everything a plant needs you improve it by adding fertilizers, soil conditioners and lime.

Organic and Inorganic

Inorganic fertilizers are classified as those fertilizers that are synthesized or mined from nonliving materials. Also known as chemical fertilizers, inorganic fertilizers are considered quick-release fertilizers; that is, the rate in which fertilizers release nutrients for the plant to absorb is relatively fast. In contrast, organic fertilizers are derived from living materials. These fertilizers are considered slow-release because it takes longer for soil microbes to release the nutrients so the plant can absorb them.

Types of Inorganic Fertilizers

Inorganic fertilizers are created in different formulas. Complete formulas contain equal or varying amounts of every nutrient, as described by the N-P-K ratio on the side of the bottle or bag, which gives the percentage of nitrogen, phosphorus and potassium the fertilizer contains. Incomplete formulas contain large quantities of one nutrient. For example, potassium fertilizers, also known as potash, are made up of potassium and little to no other nutrient. Like potash, you can find nitrogen-only and phosphorus-only formulas available in your local greenhouse.

Types of Organic Fertilizers

Organic fertilizers come in the different forms. The most common organic fertilizer is animal manure. Fish emulsion, bone meal, cottonseed meal, blood meal and sludge are other forms of organic fertilizer. According to the University of Tennessee Extension Service, organic fertilizers such as sludge are sold as soil conditioners but do not have a nutrient guarantee; they are sold to improve the soil’s physical condition.


In the case of both kinds of fertilizers, using them in the correct amounts leads to more fertile soil. Some of the specific advantages of organic fertilizers, like sludge or manure, include improved soil texture, water retention and resistance to erosion. Inorganic fertilizers, however, have the potential to increase the growth rate and your plant's overall productivity more quickly.


While both kinds of fertilizers benefit the growth and life of your plants when used properly, they can also be highly detrimental to your plants when they are used improperly. For example, when formulas high in nitrogen are overused, they cause internal chemical burns and reduce the plant’s environmental tolerances to temperature, drought and disease. In addition to causing your plants harm, excess nutrients can leach into the groundwater, causing levels of pollution to build over time.

Making The Right Choice

The University of Tennessee Extension Service states that “soil testing is the most reliable and environmentally sound method available for determining amounts of lime and fertilizers to apply.” To discover what the soil in your yard, garden or field needs, contact your county extension agent. Their job is to help you with not only soil testing procedures but application methods and seeding and planting timetables. Also, always check the label for the fertilizer’s type, N-P-K ratio and use.