Figure 7. Schematic diagram of a surfactant converting water-repellent sandy soil to water-friendly sandy soil. The tail of the applied surfactant is attracted to the water-repellent soil particle, while the head of the surfactant attracts water. In this way, the applied surfactant can improve soil quality and enhance the water-retention and nutrient-holding ability of sandy soil. The anionic surfactant can also use its negative charge to adsorb cation nutrients such as ammonium, calcium, magnesium, and potassium ions. The cationic surfactant applied can employ its positive charge to hold anionic nutrients such as nitrate, phosphate, and sulfate ions.
Credit: Guodong Liu