The world grows 95% of its food in the uppermost layer of soil, making topsoil one of the most important components of our food system ,but nearly half of the most productive soil has disappeared in the world in the last 150 years   threatening crop yields and contributing to nutrient pollution, dead zones and erosion. In the US alone, soil on crop land is eroding  10 times faster than it can be replenished. If we continue to degrade the soil at the rate we are now, the world could run out of topsoil in about 60 years, according to Maria-Helena Semedo of the UN’s Food and Agriculture Organization. Without topsoil, the earth’s ability to filter water, absorb carbon, and feed people plunges. Not only that, but the food we do grow will probably be lower in vital nutrients.