Soil erosion is a natural occurrence arising largely from rain and dust storms. This can happen to any ecosystem, and once upon a time it would not have been much of an issue; lost soil will be replaced over time. However, for obvious reasons, losing top soil-the first few inches of dirt from which plants derive most of their nutrients-is a very big problem if you're trying to grow food for a country. For this reason, Iowa, our nation's largest producer of corn, has received particular attention recently for its unparalleled loss of soil.
In the last few months, the price of corn and soybeans has increased dramatically, leading Iowa's farmers to grow these crops on a scale that is just irresponsible. To increase their yields, crops are being planted row to row all the way up to rivers and streams at the edges of a field. Not only does this type of overzealous planting cause significant farm run-off from nitrogen based fertilizers, but also creates the perfect conditions if you're looking to destroy the land for future generations. Soil erodes the fastest next to bodies of water; couple this scientific fact with artificial chemicals from industrial fertilizer, plowing, and climate change causing more frequent and severe storms throughout Iowa, and you get a state depleting its soil at a rate unacceptable to sustain this system.
For more information on the situation in Iowa and how soil loss affects our food system, I recommend you read the research recently conducted by the Environmental Working Group, an organization dedicated to distributing information related to public health and environmental protection. EWG just released a report on soil erosion, the summary of which can be found quickly and easily on youtube, and supplied here for your viewing pleasure.