Biogeochemical Cycle : The recycling of inorganic matter between living organism and their non- living environment are called biogeochemical cycles. Energy flows directionally through ecosystems, entering as sunlight (or inorganic molecules for chemoautotrophs) and leaving as heat during energy transformation between trophic levels. Rather than flowing through an ecosystem, the matter that makes up organisms is conserved and recycled. The six most common elements associated with organic molecules—carbon, nitrogen, hydrogen, oxygen, phosphorus, and sulphur—take a variety of chemical forms and may exist for long periods in the atmosphere, on land in water, or beneath earth’s surface. Geologic processes, such as weathering, erosion, water drainage, all play a role in the cycling of elements on Earth.
Biogeochemical cycles are of two types :
(i) Gaseous Cycles : Example; Oxygen cycle, carbon cycle, nitrogen cycle, water cycle. Reservior for these cycles is atmosphere.
(ii) Mineral Cycles : Example; Phosphorus cycle, sulphur cycle, calcium cycle, and potassium cycle. Reservoir of these minerals is earth crust.