Soil Has a Charge and Cation Exchange.

Physics and/or soil properties can be illustrated using a battery and soil slurry proving that soil has a charge. Building on soil charge, students learn that chemicals and/or nutrients incorporated into the soil can adsorb or leach. They can conceptualize ion leaching and adsorption processes by pouring known positively and negatively charged dyes through soil columns and observing their results. Using these same experiments, younger students can learn about charge and the fundamentals that opposite charges attract and like charges repel.