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Improving the uniformity of emitter air bubble delivery during oxygation
journal contributionposted on 06.12.2017, 00:00 by Manouchehr Torabi, David Midmore, Kerry Walsh, Surya Bhattarai
Drip irrigation may be used to deliver water and air to plant root systems, although uniformity of air bubble delivery along the irrigation line is an issue. Use of 1.2 ppm of a nonionic surfactant (alcohol alkoxylate) in an open-end drip irrigation system increased the Christiansen uniformity coefficient (CUC) of the emitter air flow rates to 80%, compared to 20% without surfactant. In a closed-end irrigation system, addition of 32 ppm surfactant raised the CUC of the emitter air flow rates from 1 to 23% for the symmetric connectors and from −83 to 37% for the asymmetric connectors, respectively, over the controls without surfactant. In the absence of the surfactant, insertion of turbulence-inducing sealing plugs before the 9.5-mm-long symmetric and asymmetric connectors raised the CUC of the emitter air flow rates from 1 to 18% for the symmetric and from −82 to −64% for the asymmetric connectors, respectively. Regardless of the type of the connectors, the highest CUC for emitter air flow rates in the closed-end system was obtained when both sealing plugs and surfactant were used.