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Submitted to: International Irrigation Show
Publication Type: Proceedings Publication Acceptance Date: 11/1/2007 Publication Date: 12/9/2007 Citation: King, B.A., Bjorneberg, D.L. 2007. Center pivot simulator for evaluating system design and management effects on infiltration and erosion. In: Proceedings of 28th International Irrigation Show, December 9-11, 2007, San Diego, California. p. 166-175. Interpretive Summary: Over the past two decades center pivot sprinkler manufacturers have, and presently, continue to develop sprinklers that reduce peak water application rates and droplet kinetic energy as a means to sustain soil infiltration rates and reduce runoff and soil erosion hazard. As a result there are numerous center pivot sprinkler choices available for the producer but little quantitative information that relates these choices to performance on a particular soil type. To begin to address this lack of information a commercial irrigation boom sprinkler system was modified to provide water application characteristics like that of a center pivot irrigation system. A cable winched mounted to the front of a tractor and the tractor hydraulic system was used to provide a means to tow the irrigation boom at a constant speed. The irrigation boom was used to investigate the effects selection of different commercial center pivot sprinklers has on runoff and erosion from a Portneuf silt loam soil. The results show that the type of center pivot sprinkler selected can have a significant effect on the amount of runoff and erosionl. Further evaluation is needed on different soil types to develop quantitative relationships describing runoff and erosion from various center pivot sprinkler types. Technical Abstract: A 4-wheeled commercial irrigation boom was modified for use in investigating center pivot design and management effects on infiltration, runoff and erosion of specific soil types. The center pivot simulator used a hydraulic winch attached to the front of a tractor for mobilization and controlled travel speed. A 3 inch diameter 300 ft drag hose is used to supply water to the center pivot simulator. The center pivot simulator was used to conduct two studies to investigate infiltration, runoff and erosion differences of common commercially available center pivot sprinkler types on a Portneuf silt loam soil. Sprinklers used in the first 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. Measured runoff was highly variable despite the controlled experimental conditions. Runoff from all sprinkler types increased with number of irrigations indicating that soil surface sealing continued to increase without reaching a maximum after five irrigations. Measured runoff tended to be the highest for the S3000 and I-Wob sprinklers. Sediment loss tended to be highest for these sprinklers as well. The second study investigated differences in runoff and erosion related to kinetic energy of sprinkler droplets from commercial center pivot sprinklers. The sprinklers used in the study were: 1) Senninger I-Wob with standard 9-groove plate, 2) Nelson R3000 with brown plate, 3) Nelson D3000 spray with flat plate and 4) sprinkler 3 with the runoff plot covered with 20-mesh nylon window screen suspended about 1 inch above the soil surface to eliminate sprinkler droplet impact on the bare soil surface. Covering the plot with screen to eliminate sprinkler droplet impact resulted in significantly (p is less than or equal to 0.05) less runoff and sediment loss for all four irrigation events. The D3000 and I-Wob sprinklers tended to have the greatest runoff and sediment losses. Sprinkler type and configuration had a significant (p is less than or equal to 0.05) effect on runoff and erosion of a Portneuf silt loam soil. |
