Controlling erosion and sediment loss on furrow-irrigated land

Erosion and sediment loss from irrigated land has been recognized as a serious problem for about 40 years. Only during the past 10 years has significant progress been made toward controlling such erosion. Carter (5) reviewed and evaluated information available before 1976 and proposed a set of guidelines for controlling erosion and sediment loss on furrow-irrigated land. Brown and associates (4) measured sediment inflows and outflows for two large irrigated tracts and provided information on sediment and phosphorus (P) concentrations in surface drainage waters or irrigation return flows (6). Sediment concentrations in return flows from these two large tracts ranged from 20 to 15,000 mg/l. Total P concentrations were proportional to sediment concentrations. Therefore, conserving sediment also conserves P. Berg and Carter (2) conducted detailed investigations of water and sediment inflows and outflows from 50 furrow-irrigated fields, They concluded that an average of 50 percent of the water applied ran off the surface. Their data have been used to develop estimated sediment losses for different crops on various slopes along the furrow (7). Additional data have been collected and several computer models are being developed to provide better estimates of erosion and sediment loss. During the past five years, considerable research has been directed toward evaluating present practices for reducing erosion and sediment loss on furrow-irrigated land. Initially, most of this research was directed at reducing the sediment concentration in irrigation return flows. Presently, greater emphasis is being placed on reducing erosion and sediment loss on individual fields. Along with the evaluation of known practices came the development and evaluation of new management alternatives for erosion and sediment loss control. Here, we report the erosion control and sediment removal efficiencies for five practices and provide information on the advantages and disadvantages of each. We also present a brief summary of the application of these practices, along with some water management practices on a 1,600-ha irrigated basin and the resulting decrease in sediment loss. Third, we present the initial results of some research on the relationship of topsoil loss from erosion to crop yield decreases, work that is just beginning