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Emitter flow rate changes caused by excavating subsurface microirrigation tubing

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Design criteria for irrigation systems are heavily optimized for uniformity of application. Therefore, measuring application uniformity is an important tool to evaluate system operation and longevity. Measuring uniformity for sprinkler systems involves catch cans located within the irrigated area. Measuring uniformity for surface microirrigation systems is a straightforward adaptation of this technique. Extending the adaptation for subsurface microirrigation systems requires that individual emitters be excavated, which presumes that the effect of soil around the emitter is negligible. The objective of the research was to measure the effect of excavating subsurface emitters on flow rate. This was done by measuring flow rate for a section of tubing, then sequentially excavating emitters and measuring flow from them with catch cans. The combined measurements allow both regression of flow rate on number of exposed emitters and the computation of the effect of excavating single emitters. Excavating an emitter increased flow rate between 2.8% and 4.0% (extremes over four laterals). Only about half of this increase could be explained by the 0.3-m head postulated to exist in soils that exhibit upwelling above subsurface emitters. The effect of excavating emitters to measure uniformity is not expected to cause significant errors in the uniformity calculation.
Sadler, E. John , Camp, Carl R. , Busscher, Warren J.
Includes references
American Society of Agricultural Engineers, c1995.
Journal Articles, USDA Authors, Peer-Reviewed
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