A compound fertilizer contains two or more essential plant nutrients and can include secondary nutrients and trace elements. The compound might be organic or inorganic. Organic compounds might include manure, fish and bone meal as well as compost. Inorganic fertilizers combine various chemicals in the manufacturing process. Combinations for different crops and growing conditions are produced.

The essential plant nutrients are nitrogen, phosphorus and potassium. These elements are required for plants to complete their life cycle. Secondary nutrients are calcium, sulfur and magnesium. These nutrients are normally present in the soil but need to be replenished periodically. Trace elements might be added, such as boron, copper and cobalt. Compound fertilizers are used around the world with several variations.

Different countries define a compound fertilizer in diverse ways. They are all similar in the respect that two or more essential nutrients are required. Although organic fertilizers are widely used, it has been estimated that inorganic fertilizers are responsible for feeding a very large percentage of people on Earth. A combination of organic and chemical fertilizers are typically used with each having certain advantages and disadvantages.

Compound fertilizer is available in liquid or granular form, and some granular fertilizer is in a slow-release formula. A numbering system is used to define the percentages of the three essential plant nutrients. For example, a 20-20-10 fertilizer would contain 20 percent nitrogen, 20 percent phosphorus and 10 percent potassium. Secondary nutrients and trace elements are typically listed.

Single-nutrient fertilizers are available, but the convenience of a compound fertilizer provides the addition of several nutrients and ease of use in the field. A uniform distribution is possible because each granule contains all of the nutrients and minerals in the formula. Blended fertilizers might not provide an even distribution of ingredients and might be more costly.

Variations of compound fertilizers are used for nearly all crops. Complex fertilizers, which are produced through chemical interaction, are used primarily for industrial crops such as cotton and sugar beets. These complex fertilizers are a type of compound fertilizer with a chemical reaction being required to complete the production process.

Commercially available compounds are typically free-flowing, allowing a uniform dispersion. They are chemically uniform and safe to use. Controlled-release elements are used to avoid burning vegetation. Some products contain herbicides for a controlled feed and weed application.

Many production methods are being used to manufacture these fertilizers. Compound fertilizers are available from home improvement stores. Landscaping and agricultural supply stores also carry a full line of compound fertilizer products. Homeowners often find compound products convenient, reliable and economic.