The sulfur cycle are the collection of processes by which sulfur moves to and from minerals (including the waterways) and living systems. Such biogeochemical cycle

Biogeochemical cycle

In ecology and Earth science, a biogeochemical cycle or substance turnover or cycling of substances is a pathway by which a chemical element or molecule moves through both biotic and abiotic compartments of Earth. A cycle is a series of change which comes back to the starting point and which can...

s are important in geology

Geology

Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...

 because they affect many minerals. Biogeochemical cycles are also important for life because sulfur

Sulfur

Sulfur or sulphur is the chemical element with atomic number 16. In the periodic table it is represented by the symbol S. It is an abundant, multivalent non-metal. Under normal conditions, sulfur atoms form cyclic octatomic molecules with chemical formula S8. Elemental sulfur is a bright yellow...

 is an essential element, being a constituent of many protein

Protein

Proteins are biochemical compounds consisting of one or more polypeptides typically folded into a globular or fibrous form, facilitating a biological function. A polypeptide is a single linear polymer chain of amino acids bonded together by peptide bonds between the carboxyl and amino groups of...

s and cofactor

Cofactor

Cofactor may refer to any of the following:* Cofactor , the signed minor of a matrix* Minor , an alternative name for the determinant of a smaller matrix than that which it describes...

s.

Steps of the sulfur cycle are:

• Mineralization of organic sulfur
  Organosulfur compounds
  Organosulfur compounds are organic compounds that contain sulfur. They are often associated with foul odours, but many of the sweetest compounds known are organosulfur derivatives. Nature abounds with organosulfur compounds—sulfur is essential for life. Two of the 20 common amino acids are...
  
   into inorganic forms, such as hydrogen sulfide
  Hydrogen sulfide
  Hydrogen sulfide is the chemical compound with the formula . It is a colorless, very poisonous, flammable gas with the characteristic foul odor of expired eggs perceptible at concentrations as low as 0.00047 parts per million...
  
   (H₂S), elemental sulfur, as well as sulfide mineralss.
• Oxidation of hydrogen sulfide, sulfide
  Sulfide
  A sulfide is an anion of sulfur in its lowest oxidation state of 2-. Sulfide is also a slightly archaic term for thioethers, a common type of organosulfur compound that are well known for their bad odors.- Properties :...
  
  , and elemental sulfur (S) to sulfate
  Sulfate
  In inorganic chemistry, a sulfate is a salt of sulfuric acid.-Chemical properties:...
  
   (SO₄^2–).
• Reduction of sulfate to sulfide.
• Incorporation sulfide into organic compounds (including metal-containing derivatives).

These are often termed as follows:

Assimilative sulfate reduction (see also sulfur assimilation

Sulfur assimilation

Sulfur is an essential element for growth and physiological functioning of plants. However, its content strongly varies between plant species and it ranges from 0.1 to 6 % of the plants' dry weight. Sulfates taken up by the roots are the major sulfur source for growth, though it has to be reduced...

) in which sulfate (SO₄^2–) is reduced by plant

Plant

Plants are living organisms belonging to the kingdom Plantae. Precise definitions of the kingdom vary, but as the term is used here, plants include familiar organisms such as trees, flowers, herbs, bushes, grasses, vines, ferns, mosses, and green algae. The group is also called green plants or...

s, fungi and various prokaryote

Prokaryote

The prokaryotes are a group of organisms that lack a cell nucleus , or any other membrane-bound organelles. The organisms that have a cell nucleus are called eukaryotes. Most prokaryotes are unicellular, but a few such as myxobacteria have multicellular stages in their life cycles...

s.