> 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/management-practices/chem_app.ops/surf_frac.md).

# surf\_frac

Surface fraction

Amount of the chemical applied to the upper 10 mm of the soil.