Soils - Part 7: Soil and Plant Considerations for Calcium, Magnesium, Sulfur, Zinc, and other Micronutrients Glossary

ammonium sulfate

A dry crystalline material (21-0-0 +24S) produced by reacting anhydrous ammonia with sulfuric acid; stores well.  An excellent choice when both nitrogen and sulfur are needed.

ammonium thiosulfate

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.


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.

elemental form

 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.


Elements needed in very small amounts for plant growth.  Micronutrients include zinc, iron, chlorine, copper, manganese, boron and molybdenum.

organic matter

Material that contains carbon and is found in the soil. Most soil organic matter comes from previously living organisms.  Temperature and moisture are the two main factors affecting its development.


The measurement of an aqueous solution’s acidity and alkalinity; measured on a scale of 1 to 14. Pure water has a pH of 7.0 and is neutral. Different crops grow best at different pH levels; pH influences herbicide activity and nutrient uptake.


An essential plant nutrient needed in large amounts.  Postassium is vital to plant nutrient absorption, respiration, transpiration and enzyme activity. The major portion of potassium is contained in minerals such as feldspar and mica, and clays such as montmorillonite, vermiculite and illite.

potassium-magnesium sulfate

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

soil test

Chemical analysis of soil samples to assess soil nutrient levels and determine how fertilizer use can be improved.

zinc chelates

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.