> For the complete documentation index, see [llms.txt](https://swatplus.gitbook.io/io-docs/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://swatplus.gitbook.io/io-docs/introduction-1/aquifers/aquifer.aqu/sol_p.md).

# sol\_p

This is a fixed concentration used throughout the entire period of simulation. Accordingly, groundwater phosphorus loads only vary with groundwater flow.