Biogeochemical cycling means

Biogeochemical cycling means cycling of nutrients in an ecosystem.
A biogeochemical cycle is a pathway by which a chemical substance cycles the biotic and the abiotic compartments of Earth.
The biotic compartment is the biosphere and the abiotic compartments are the atmosphere, hydrosphere and lithosphere.
Energy flows directionally through ecosystems, entering as sunlight and leaving as heat during the many transfers between trophic levels.