Intentional filling of basins with soil from adjacent uplands occurs, but is not common. More insidious is the gradual siltation of basins caused by soil erosion from adjacent cropland. This cause of wetland degradation has become more severe in recent years with the advent of larger, more powerful farm equipment that allows cultivation of entire basins and their steeply rolling watersheds. Increased siltation to basins can also be attributed partly to expanded planting of row crops, particularly corn, sunflower, and soybean. Row crops generally result in more soil erosion than small grains, because of the additional cultivation required during the growing season.
Agricultural chemicals exert a subtle but pervasive influence on prairie wetlands.
Agricultural chemicals are widely used in association with growing intensification of land use in the Dakota. Widespread aerial application of agricultural chemicals in the Dakotas exposes wetland animal life and plants to overspray and drift. If degradation and destruction of waterfowl breeding habitat continues at present rates into the next century, stocks of ducks can be expected to decline accordingly. Therefore, a wide array of measures will be needed to partially circumvent these losses, including increased production of waterfowl on publicly owned lands, restoration of lands that formerly were prime breeding habitat, and slowing further habitat loss.