mineral salt

In nutrition, simple inorganic chemicals that are required, as nutrients, by living organisms. Plants usually obtain their mineral salts from the soil, while animals get theirs from their food. Important mineral salts include iron salts (needed by both plants and animals), magnesium salts (needed mainly by plants, to make chlorophyll), and calcium salts (needed by animals to make bone or shell). A trace element is required only in tiny amounts.

Mineral salts are taken up in soluble form. When mineral salts dissolve in water they separate into particles called ions. Mineral salts do not usually contain the element carbon and are therefore inorganic (organic compounds always contain carbon).

Plant roots absorb individual mineral ions from soil water. Some of the ions travel by diffusion into the root; others are absorbed by active transport. The minerals required in the greatest amounts are those containing the element nitrogen, for example nitrate ions (or ‘nitrates’), which are a key component of inorganic fertilizer. A plant uses nitrates in the production of proteins such as enzymes, so they are important for plant growth. They are often in short supply in the soil, which is why inorganic fertilizers are required. Plants also require magnesium in order to make chlorophyll, the green chemical that absorbs the energy of sunlight for photosynthesis.

Mammals absorb the mineral salts they need from their food. Important mineral salts include iron salts (needed for haemoglobin) and calcium salts (needed by animals to make bone). Both plants and animals need a range of other minerals in tiny amounts (trace elements).