The Azimuth Project
Phosphorus cycle



According to Wikipedia:

The phosphorus cycle is the biogeochemical cycle that describes the movement of phosphorus through the lithosphere, hydrosphere, and biosphere. Unlike many other biogeochemical cycles, the atmosphere does not play a significant role in the movement of phosphorus, because phosphorus and phosphorus-based compounds are usually solids at the typical ranges of temperature and pressure found on Earth.

The production of phosphine gas is allowed only in specialized, local conditions. Low phosphorus (chemical symbol, PP) availability slows down microbial growth, which has been shown in studies of soil microbial biomass. Soil microorganisms act as sinks and sources of available PP in the biogeochemical cycle. However, the major transfers in the global cycle of PP are not driven by microbial reactions. Further studies need to be performed for integrating different processes and factors related to gross phosphorus mineralization and microbial phosphorus turnover in general.

The phosphorus cycle is of special interest because phosphorus is a limiting factor in agriculture and more generally life on Earth; see our article Peak phosphorus for more on the dangers this may pose.


Here we show how Phosphorus has changed. Here we show the prehuman levels:

and here is the current PP-cycle after mankind appeared:


Abstract Phosphorus is a critical element in the biosphere, limiting biological productivity and thus modulating the global carbon cycle and climate. Fluxes of the global phosphorus cycle remain poorly constrained. The prehuman reactive phosphorus flux to the ocean is estimated to range from 0.7—4.8 x 10 1210 ^12 g/yr. Uncertainty in the reactive phosphorus flux hinges primarily on the uncertain fate of phosphate adsorbed to iron oxyhydroxide particles which are estimated to constitute 50% or more of the chemically weathered-phosphorus river flux.

Most reactive phosphorus is initially removed from seawater by burial of organic matter and by scavenging onto iron–manganese oxide particles derived from mid-ocean ridge (MOR) hydrothermal activity. Calculation of the oceanic phosphorus burial flux is complicated by early diagenetic redistribution of both oceanic and terrestrial phosphorus. Increased phosphorus input during periods of warm, humid climate is offset to some degree by increased burial rate as productivity shifts to expanded shallow-water estuary and shelf areas where phosphorus is rapidly decoupled from organic matter to form phosphorite. Phosphorus scavenging is greater if high sea levels are associated with increased MOR hydrothermal activity such as during the Late Cretaceous.

Less phosphorus is derived from weathering during cool, dry climatic periods but a more direct transportation of phosphorus to the deep ocean, and a shift of productive upwelling regions to deeper water areas allows more phosphorus to be recycled in the water column. Lowered sea level results in less effective trapping of phosphorus in constricted estuary and shelf areas and in an increase in the phosphorus flux to the deep ocean from sediment resuspension.

A decrease in MOR spreading rates and the resulting decrease in phosphorus scavenging by iron–manganese oxide particles would result in more phosphorus for the biosphere. Orogeny and glaciation may accelerate chemical weathering of phosphorus from the continents when the increased particle flux is exposed to warm and humid climate. Large, reworked phosphorite deposits may proxy for short-term organic carbon burial and correspond to periods of increased reactive phosphorus input that cannot be accommodated by longterm organic matter and iron-oxide particulate burial.