# Nutrient Reduction Models In addition to the mechanisms by which sediment and runoff are captured, nutrients may be adsorbed onto vegetation, surface residues, or the soil surface (Barfield et al., 1998). For the sake of simplicity, nutrient reduction was considered to be a function of sediment or runoff reduction only. Only nitrogen and phosphorus were considered. All nutrient models were developed from measured VFS data; the current version of VFSMOD does not account for nutrients. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://swatplus.gitbook.io/io-docs/theoretical-documentation/section-6-management-practices/filter-strips-and-grassed-waterways/filter-strips/nutrient-reduction-models.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.