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United States Department of Agriculture

Agricultural Research Service

Title: A Variable Flow Control System for Subsurface Drip Irrigation*

Authors
item Zhu, Heping
item Sorensen, Ronald
item Butts, Christopher
item Lamb, Marshall
item Blankenship, Paul

Submitted to: Journal of the Agricultural Association of China
Publication Type: Proceedings
Publication Acceptance Date: July 3, 2002
Publication Date: November 15, 2002
Citation: Zhu, H., D. L. Rowland, J. W. Dorner, R. C. Derksen, R. B. Sorensen. Influence of plant structure, orifice size and nozzle inclination on spray penetration into peanut canopy. Applied Eng. in Agric. 2002. v.45(5). p.5-1301.

Interpretive Summary: Subsurface drip irrigation (SDI) has great potential to precisely deliver water, nutrients, and chemicals to the crop root zone. It is important for an irrigation system to have a stable constant pressure to efficiently deliver water for crops. Current flow control methods used for SDI are expensive and difficult to maintain. A simple mechanical flow control system with a pressure regulating valve was tested for its ability to maintain constant pressure under variable flow conditions. The control system was tested using three commonly used pumps over a range of flow rates and pressures. As long as the pumps were able to provide enough flow to maintain a minimum pressure differential between control system inlet and outlet, the line pressure remained constant and stable throughout the tests. As a result of these tests, two flow control systems with different size pressure regulating valves were installed in two irrigation systems in Shellman, GA. The flow control systems operated satisfactorily throughout the 2001 and 2002 growing seasons and provided a stable operating pressure, avoided water hammer, and reduced total energy consumption for both SDI and sprinkler irrigation systems.

Technical Abstract: It is important for an irrigation system to have a stable constant pressure to obtain efficient water management for crops. A simple mechanical flow control system with a pressure regulating valve was investigated for subsurface drip irrigation to maintain constant pressure under variable flow conditions. A submersible pump, booster pump and centrifugal pump were tested with the control system for flow rates ranging from 9.6 to 222.1 L/min and pressures ranging from 69 to 276 kPa. As long as the pumps were able to provide enough flow to maintain a pressure differential of 124 kPa between control system inlet and outlet, the line pressure remained constant and stable through the test. The irrigation system with the flow control avoided pressure pulsation and water hammer and reduced total energy consumption.

Last Modified: 8/27/2014
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