Soil science has its own set of terms and phrases that fit for describing how soils function to provide a growing medium for plants. If you see a term that needs some definition in order to read a soil report, diagnose a plant problem or just add to your vocabulary, start here with the alphabetical list. Terms that are not defined can be brought to our attention by contacting Dr. GoodEarth.
Absorption Absorption is the taking-up of nutrients in the soil (via soil water) by the plant roots.
When plant roots take up water from the soil, they also absorb soil nutrients that are dissolved in the water. Adsorption is the term used to express this action of moving nutrients from the soil into the plant.
Aggregate An aggregate is a collection of soil particles held together to form a clod.
Soil particles can be thought of as tiny units of soil. When these become "glued" together to form larger units, they begin to gain size and between them are air spaces where water and air are exchanged. The soil structure is formed by soil particles sticking together to make larger units that we sometimes refer to as clods. Clods can be picked up by hand and crumbled into tiny particles. The soil structure becomes destroyed when it is broken down to dust-like particles where not air spaces and water spaces are present. Plant roots need air and water spaces to exchange oxygen and adsorb nutrients.
Anion Anions are negetively charged elements (nutrients) in the soil.
Anions are nutrients that have a negative charge balance as a result of neutrons (positive charge) and electrons (negative charge). Important anions nutrients for plants include nitrogen (as nitrate), phosphorus (as phosphate)and sulfur (as sulfate). Each of these is a negatively charged element, taken up by plant roots from the soil water.