What is the medium by which the carbon cycle takes place?

$A$ farmer harvests his crop and expresses his harvest in three different ways.
$(a)$ $I$ have harvested $10$ quintals of wheat.
$(b)$ $I$ have harvested $10$ quintals of wheat today in one acre of land.
$(c)$ $I$ have harvested $10$ quintals of wheat in one acre of land,$6$ months after sowing.
Do the above statements mean one and the same thing? If your answer is yes,give reasons. If your answer is 'no',explain the meaning of each expression.

$A$ biogeochemical cycle without an atmospheric component is

In a food chain,the initial organisms are:

How many years on average are required for the formation of a grassland in secondary succession?

Outline the salient features of carbon cycling in an ecosystem.