Furrow Erosion and Sediment Losses on Irrigated Cropland

Sediment losses from furrow erosion on irrigated cropland ranged from 0.5 to 142 metric tons per hectare (0.2 to 63.0 tons/acre) on 49 Idaho fields during one irrigation season. Field slope varied from 1.0 to 5.0 percent and furrow stream size from 11.3 to 49.9 liters per minute (3.0 to 13.2 gal/min). Erosion increased sharply on row-cropped fields when slopes exceeded 1.0 percent. Furrow erosion can be reduced by: (a) reducing furrow stream size when water reaches the furrow ends, (b) avoiding irrigation of row crops on slopes that are too steep, (c) keeping the tailwater ditch shallow and the water in it moving slowly, (d) installing tailwater control systems, and (e) alternate-furrow irrigation. Sediment losses from irrigated lands can also be reduced markedly by planting vegetative filter strips and using sediment retention basins. Total phosphorus losses were reduced in proportion to the reduction in sediment losses