"Our homes have locks on the door, latches on the window, and insurance policies in the dresser drawer.... Meanwhile, outside our windows, every rainstorm carries away thousands of tons of valuable topsoil upon which we depend for our very survival." -- Malcolm Margolin, Naturalist
Although soil seems to be everywhere underfoot, our nutrient-rich topsoil forms a very thin layer on which we depend for our survival. More than 4 billion tons of topsoil are lost through erosion by wind, water, and ice each year, yet it can take hundreds of years to regenerate just one inch of topsoil! Your students might first explore the impact of plants and plant roots on reducing soil erosion by choosing different areas around school, including some areas with exposed soil and other areas with plants.
Place 2-foot-tall white stakes, marked at 1-inch intervals, in the ground. After a rain, measure how high mud has splashed on each stake. Discuss the implications for farmers and gardeners. Once students have begun to understand the problem, challenge them to look for evidence of erosion around the school and in the community and to explore some solutions. Generate a list of other ways in which we both deplete and enhance soil, then detail what students can do to lessen their impact and/or enhance the soil health.