Two or more incomplete fertilizers can be used separately or combined to supply the needed nutrients often at a reduce cost compared to using a complete fertilizer. Examples of incomplete fertilizers include:

Ammonium sulfate (21 percent nitrogen) is a preferred source of nitrogen for plants that require acid soils.

Ammonium nitrate (33 percent nitrogen) is a quick acting form of nitrogen. It tends to adsorb water from the air and cake if not kept in an air tight container.

Borax (11.3 percent boron), sodium borate (20 percent boron), and Solubor (20 percent boron) are common sources of boron.

Magnesium sulfate (Epsom salts) (10 percent magnesium and 14 percent sulfur) is a highly soluble source of magnesium and sulfur.

Muriate of potash (60 percent potash) is a naturally occurring material that has been processed to remove impurities and concentrate the product.

Rock phosphate (30 to 36 percent phosphorus) is a natural fertilizer that releases phosphorus very slowly. It is very insoluble in soil above pH 6.0.

Sodium nitrate (16 percent nitrogen) is a quick acting source of nitrogen. It is also called nitrate of soda.

Triple superphosphate (46 percent phosphorus) and superphosphate (20 percent phosphorus) are the most commonly used forms of phosphorus. The phosphorus and sulfur are readily available.

Urea (45 percent nitrogen) is a synthetic organic nitrogen source.

Consumer Horticulture | Quick Reference

© Erv Evans, Consumer Horticulturist
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