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United States Department of Agriculture

Agricultural Research Service

Research Project: IMPROVED WATER RESOURCES MANAGEMENT FOR IRRIGATED AGRICULTURE IN THE PACIFIC NORTHWEST

Location: Northwest Irrigation and Soils Research

Title: Evaluation of potential runoff and erosion of four center pivot irrigation sprinklers

Authors
item King, Bradley
item Bjorneberg, David

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: September 23, 2010
Publication Date: February 10, 2011
Citation: King, B.A., Bjorneberg, D.L. 2011. Evaluation of potential runoff and erosion of four center pivot irrigation sprinklers. Applied Engineering in Agriculture. 27(1):75-85.

Interpretive Summary: Water application rates along the outer portion of a center pivot irrigation system, which influences the most acres, often exceed soil infiltration rates for medium- and fine-textured soils can result in substantial runoff, erosion and spatial non-uniformity in water application depth on rolling topography. The primary emphasis for many center pivot sprinkler product developments and application studies has been to attain high uniformity of water application, which actually is not the main challenge for good water application at the outer end of center pivot sprinkler irrigation systems. Over the past two decades center pivot sprinkler manufacturers have developed sprinklers that minimize peak water application rates while sustaining high application uniformity. There are numerous center pivot sprinkler choices available but little quantitative information that relates sprinkler selection to infiltration, runoff, and erosion on a particular soil. 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. Based on manufacturer’s published sprinkler nozzle flow rates, up to 12% variation in applied water was measured between sprinkler types. Testing of sprinkler nozzle flow rates revealed up to an 8.6% difference between measured nozzle flow rate and manufacturer’s published data. Significant differences in runoff and erosion between sprinkler types were observed but were not consistent across all runoff tests or soil types. In general, sprinkler types that visually appear to more uniformly distribute sprinkler droplets over the wetted area with respect to time exhibited the greatest measured erosion rates. This functional difference in water application may cause sediment to remain in suspension in overland flow for a longer duration allowing sediment to be more readily transported down slope. A 50% reduction in sprinkler flow rate reduced runoff and soil erosion 60 to 80% for the same volume of water applied over six irrigations. Reducing sprinkler flow rate early in the growing season prior to crop canopy development could be an effective management tool for reducing sprinkler runoff and erosion.

Technical Abstract: 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 for specific soil types. The objective of this study was to evaluate potential runoff and erosion from four 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. Based on manufacturer’s published sprinkler nozzle flow rates, up to 12% variation in applied water was measured between sprinkler types. Testing of sprinkler nozzle flow rates revealed up to an 8.6% difference between measured nozzle flow rate and manufacturer’s published data. Significant differences in runoff and erosion between sprinkler types were observed but were not consistent across all runoff tests or soil types. In general, sprinkler types that visually appear to more uniformly distribute sprinkler droplets over the wetted area with respect to time exhibited the greatest measured erosion rates. This functional difference in water application may cause sediment to remain in suspension in overland flow for a longer duration allowing sediment to be more readily transported down slope. A 50% reduction in sprinkler flow rate reduced runoff and soil erosion 60 to 80% for the same volume of water applied over six irrigations. Reducing sprinkler flow rate early in the growing season prior to crop canopy development could be an effective management tool for reducing sprinkler runoff and erosion.

Last Modified: 9/2/2014
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