Potential runoff and erosion comparison of center pivot sprinklers on three Idaho soils

The operational characteristics of center pivot sprinklers are well documented but few studies have been conducted to evaluate the effects that operating characteristics of a particular sprinkler have on infiltration, runoff, and erosion of specific soil types. The objective of this study was to evaluate potential runoff and erosion from common commercial center pivot sprinklers on three widely distributed, south central Idaho soils. A modified commercial irrigation boom system was used to emulate center pivot irrigation on experimental runoff plots. Sprinklers used in the study were: 1) Nelson R3000 with brown plate, 2) Nelson R3000 with red plate, 3) Nelson S3000 with purple plate, and 4) Senninger I-Wob with standard 9-groove plate. There were significant differences in runoff and erosion rates between sprinkler types for the soils tested and experimental conditions. The I-Wob exhibited the highest overall runoff and erosion rates and the R3000 sprinklers exhibited the lowest rates for the three soils tested. In general, sprinkler types that visually appear to more uniformly distribute sprinkler droplets over the wetted area with respect to time exhibited the highest runoff and erosion rates. The relative differences in runoff between the sprinklers tested for the three soils were not directly proportional to droplet kinetic energy. This outcome is in conflict with conventional theory on soil surface sealing from droplet impact.