Soils - Part 8: Characteristics of Fertilizer Materials Glossary

ammonium nitrate-sulfate

A dry nitrogen fertilizer (30-0-0 + 6.5S) manufactured by reacting anhydrous ammonia with a mixture of nitric acid and sulfuric acid; good storage and handling characteristics.

ammonium phosphate

A material produced by reacting ammonia with phosphoric acid or a mixture of phosphoric and either sulfuric or nitric acids.  Ammonium phosphate is the leading nitrogen-phosphorus product in the fertilizer industry; high analysis, high water solubility, good physical characteristics and low production costs.

ammonium thiosulfate solution (ATS)

The most commonly used source of sulfur in fluid fertilizer; weighs 11.5 lbs./gal. After application to the soil, thiosulfate is decomposed to form approximately equal amounts of sulfate sulfur and elemental sulfur

anhydrous ammonia

A gaseous material that is compressed and stored as a liquid. At 60oF, a gallon of anhydrous ammonia weighs 5.15 pounds. Due to the fact anhydrous ammonia needs to go through the nitrification process, it is more resistant to losses from the soil by leaching or denitrification because it is converted by bacterial action to the nitrate form more slowly than are other nitrogen sources.

aqua ammonia

Anyhdrous ammonia dissolved in water. It is a low pressure solution and contains free ammonia, the amount of which increases as air temperature increases.

calcium sulfate

A byproduct of manufacturing concentrated superphosphate; contains 15-18 percent sulfur.

concentrated superphosphate

A material manufactured by reacting phosphoric acid with finely ground rock phosphate; often used in bulk blended products.

elemental sulfur

The most concentrated form of sulfur.  Elemental sulfur must be oxidized to the sulfate form before plants can use it.  It must be finely ground to particle sizes of 80-100 mesh to be oxidized and effective during the same growing season.

ferrous sulfate

 The most commonly used inorganic iron source, which is 20 percent iron and 18.8 percent sulfur.  It is not effective as a soil-applied material because it quickly reverts to an unavailable form.


The process by which organic nitrogen is converted to nitrate through bacterial activity, and as influenced by temperature and precipitation.

nitrogen-phosphorus-potassium fertilizers

Fertilizers manufactured using ammonium phosphate, to which potassium (usually potassium chloride) and water have been added; additional nitrogen and other nutrients also may be added.

ordinary superphosphate

A material produced by reacting sulfuric acid with finely ground rock phosphate; about 85-90 percent water soluble.  An excellent source of phosphorus and sulfur.

phosphoric acid

Material produced by treating finely ground rock phosphate with sulfuric acid or by smelting (burning) rock phosphate with coke and silica in an electric furnace and reacting with water. Agricultural grade phosphoric acid is seldom used for direct application because of its corrosive properties; it is usually used to make other forms of phosphoric fertilizers.

potassium chloride

The most commonly used and most economical potassium fertilizer.  It is mined as sylvinite from underground mines or by solution mining in New Mexico, Utah, California and Michigan.

potassium sulfate

Material used as a potassium fertilizer for crops where the chloride content of potassium chloride is undesirable.

potassium-magnesium sulfate (Sul Po Mag)

A double salt of potassium and magnesium sulfate; commonly used as a dry granular source of potassium, magnesium and sulfur.

superphosphoric acid

A mixture of polyphosphate and orthophosphate made by dehydrating water from phosphoric acid; used to produce ammonium polyphosphate fertilizers.


A dry nitrogen material produced by reacting ammonia with carbon dioxide.  Urea contains the highest percentage of nitrogen of the commonly used dry fertilizers and is rapidly replacing ammonium nitrate. When surface applied, urea is the most rapidly volatilized of the dry nitrogen materials.

urea-ammonium nitrate

A nonpressure solution of ammonium nitrate, urea and water. Two grades are most common: 28-0-0 (10.7 lbs./gal.) and 32-0-0 (11.1 lbs./gal.).

zinc carbonate

Inorganic compounds that are very insoluble in water.  If granulated, zinc carbonate is not an effective source of zinc; however, it is effective if very finely ground.

zinc chelate (Zn-EDTA most common)

Material blended with dry fertilizers and applied in a row band.  Granular zinc chelate is likely to be more effective than granular zinc sulfate because of its mobility.

zinc oxide

Inorganic compounds that are very insoluble in water.  Zinc oxide is not effective as a source of zinc if granulated, but is effective when finely ground.

zinc sulfate

Relatively water-soluble inorganic compound.  The most commonly used dry zinc material.