When creeks, streams, and rivers flood, the energy contained in the increased flow of water causes sediment on the banks to erode and move with the water. The amount of additional sediment coming from flooded fields will depend on tillage system, soil slope, previous crop, and amount of water flowing across those fields. Flood waters often appear orangish-brown. The color is from soil sediments suspended in the water. These sediments will settle out as water flow rate decreases.
Sediments consist of sand, silt, and clay particles.
Flooding of most agricultural fields is away from the main water flow, where the water has a slow flow rate. The layer of deposition is a function of the length of time the field was flooded, the amount of sediment in the water, and the rate of flow of the water across these fields. In most cases this layer is visible and can measure up to a fraction of an inch. However, because this represents a relatively small amount of soil added compared to the entire topsoil quantity, soil tests that were taken last fall will still be representative of the fields and should be used in making fertilizer recommendation. We maintain a page with information about this web server.