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Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal Publication Acceptance Date: 6/1/2002 Publication Date: 12/5/2002 Citation: Sorensen, R. B., F. S. Wright. Soil temperature in the peanut pod zone with subsurface drip irrigation. Peanut Sci. 2002. v.(2)29: p.115-122. Interpretive Summary: Subsurface drip irrigation (SDI) has great potential to precisely deliver water, nutrients, and chemicals to the crop root zone. Acreage with SDI has increased considerably since last two decades due to reliable technology and potential water resource protection. It is important for an irrigation system to have a stable constant pressure to obtain efficient water management 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 investigated for SDI to maintain constant pressure under variable flow conditions. A submersible pump, booster pump and centrifugal pump were tested with the control system for wide ranges of flow rate and pressure. 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 through the tests. As the result of the tests, two flow control systems with different size pressure regulating valves were installed in two irrigation systems in Shellman, Georgia in 2001. The flow control systems operated satisfactorily throughout the 2001 growing season and maintained the stable pressure for both SDI and sprinkler systems. The irrigation system with the flow control avoided pressure pulsation and water hammer and reduced total energy assumption. 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 and small acreage sprinkler irrigation to maintain constant pressure under variable flow conditions. A submersible pump, booster pump and centrifugal pump were tested with the control system for the variable flow rates ranging from 9.6 to 222.1 L/min and pressure 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. Standard deviation of the pressure from the flow control system at 69 kPa pressure setting was 0.4 kPa for the submersible pump, 1.2 kPa for the booster pump, and 3.9 kPa for the centrifugal pump. At 69 kPa pressure setting the amperage to the booster pump decreased from 11.3 to 8.8 amp when the total flow rate in the line decreased from 158.1 to 41.2 L/min. The irrigation system with the flow control avoided pressure pulsation and reduced total energy assumption. |
