# Soils The physical soil properties are summarized in the file [**soils.sol**](/io-docs/introduction-1/soils/soils.sol.md). The physical properties of the soil govern the movement of water and air through the profile and have a major impact on the cycling of water within the HRU. The contents of nutrients and constituents in the soil are initialized using the file [**soil\_plant.ini**](/io-docs/introduction-1/initialization/soil_plant.ini.md), which references the files [**nutrients.sol**](/io-docs/introduction-1/soils/nutrients.sol.md) for the initial nutrient contents and the files [**pest\_hru.ini**](/io-docs/introduction-1/initialization/pest_hru.ini.md) and [**salt\_hru.ini**](/io-docs/introduction-1/initialization/salt_hru.ini.md) for the initial contents of pesticides and salts in the soil. --- # 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/introduction-1/soils.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.