> 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/basin-1/parameters.bsn/p_perc.md).

# p\_perc

The phosphorus percolation coefficient is the ratio of the solution phosphorus concentration in the top 10 mm of soil to the concentration of phosphorus in the percolate.