The rate of soil runoff from Iowa fields may be many times higher than previous estimates, according to a recent study.
The report, released by Environmental Working Group, shows that Iowa fields are eroding at unacceptable rates, depleting Iowa’s rich topsoil and sending sediment and chemicals into streams and rivers. Between 2002 and 2010, many fields consistently lost more than the sustainable rate of five tons of soil per acre from storms and other erosion events. A single storm in May of 2007 eroded up to 100 tons of soil per acre.
Much of the soil is carried away by gullies that are increasingly appearing in Iowa fields. These low channels are a telltale sign of high erosion, and are often refilled with soil only to be emptied again with the next storm.
High erosion creates high agricultural and environmental risks by carrying away Iowa’s rich topsoil and by polluting waterways with sediment and chemicals. An effective means of curbing this is to plant grass and trees along the edges of fields and in areas where gullies are likely to form. A series of buffers implemented in various fields reduced sediment, nitrogen and phosphorus by more than 90 percent in 2009.