Soil Has a Charge! Activity Source: Soil Science Society of America Grade Levels: 7-10 Background Soils transport water and provide homes for trillions of bacteria and other organisms. Soils also contain solids (sand, silt, clay, organic matter) with pores between them filled with air and water. The soil solids affect the ability of soil to hold and release plant nutrients. Plant nutrients are ions (see Analysis question #2 for examples) which are atoms or molecules with a net electrical charge. [Read More]