In case of which one of the following biogeochemical cycles, the weath

In case of which one of the following biogeochemical cycles, the weathering of rocks is the main source of release of nutrient to enter the cycle?

Carbon cycle
Nitrogen cycle
Phosphorus cycle
Sulphur cycle
This question was previously asked in
UPSC IAS – 2021
Option C is the correct answer. In the phosphorus cycle, the main reservoir of phosphorus is in rocks and minerals. Weathering of these rocks releases phosphorus into the soil and water.
The phosphorus cycle is unique among major biogeochemical cycles in that it does not have a significant atmospheric gaseous phase. The primary source of phosphorus for ecosystems is the slow weathering of phosphate-bearing rocks.
The carbon cycle involves atmospheric CO2, oceans, biomass, and fossil fuels. The nitrogen cycle primarily involves atmospheric nitrogen (N2) fixed by microbes, as well as organic matter decomposition. The sulphur cycle involves minerals (sulfates), atmospheric gases (SO2, H2S), and biological processes. While rocks can be a source in other cycles (e.g., sulfates in gypsum), rock weathering is the fundamental initial step that makes phosphorus available in most ecosystems.