1 3 Irrig Sci (2016) 34:421–430 DOI 10.1007/s00271-016-0512-x ORIGINAL PAPER Temporal and spatial dimension of dissolved oxygen saturation with fluidic oscillator and Mazzei air injector in soil-less irrigation systems Hongjun Lei 1 · Surya Bhattarai 2 · Ron Balsys 3 · David J. Midmore 2 · Thomas Holmes 4 · William Zimmerman 4 Received: 30 June 2015 / Accepted: 15 June 2016 / Published online: 5 July 2016 © Springer-Verlag Berlin Heidelberg 2016 tank and feeding pots after aeration. Incorporation of sur- factant in the irrigation water significantly improved DO level for the VT and FO treatment. Typically the DO lev- els reached a peak when the pump is turned off and then decline to a minimum after 24 h. The VT and FO systems had a higher magnitude and duration of the DO level in the water in all treatments compared to the CK system. The FO aeration maintained the longest duration of elevated DO in the water by a factor of two compared to the VT aeration. Compared to the CK, the best result on longevity and DO concentration was achieved using 4 ppm of a non-ionic sur- factant. The corn biomass was significantly greater for the VT compared to both the FO and CK treatments. Introduction Drip irrigation (DI) and sub-surface drip irrigation (SDI) have a major problem in terms of constraining root access to oxygen (Meek et al. 1983; Mukhtar et al. 1987; Bhattarai et al. 2005; Bonachela et al. 2010; Chen et al. 2011; Niu et al. 2012), particularly under heavy clay and soils that are compacted, saline/sodic or prone to hypoxia/anoxia. Sus- tained wetting fronts cause hypoxia in the soil that inter- feres with both plant root and soil microbe metabolism, resulting in reduced soil processes and slow nutrient miner- alisation (Jackson et al. 1992). A number of previous stud- ies (e.g. Maestre-Valero and Martinez-Alvarez 2010; Ityel et al. 2013) have highlighted the need to aerate stagnant or de-oxygenated water reserves prior to their use in irriga- tion, for the same reason. There is no general consensus of the level of dissolved oxygen (DO) required in the rhizosphere, but it is generally agreed that anoxia occurs at less than 2 ppm DO, hypoxia between 2 to 4 ppm and normoxia at 8 to 12 ppm DO. Abstract The wider scale use of aerated water for irriga- tion has been limited by dis-uniformity of aeration in the field, limited longevity of oxygen in irrigation water and lack of knowledge of what oxygen concentration brings optimal growth. Two options are presented for increasing dissolved oxygen (DO) in irrigation water: Venturi (VT) and fluidic oscillator (FO) aeration systems. Sweet corn was grown in pots to evaluate the effect of aerated water. Compared to the control treatment (CK), VT and FO showed an increase in irrigated water DO in the irrigation Communicated by D. Intrigliolo. * Ron Balsys r.balsys@cqu.edu.au Hongjun Lei 403092590@qq.com Surya Bhattarai s.bhattarai@cqu.edu.au David J. Midmore d.midmore@cqu.edu.au Thomas Holmes tdholmes1@sheffield.ac.uk William Zimmerman w.zimmerman@sheffield.ac.uk 1 School of Water Conservancy, North China University of Water Resources and Electric Power, Zhengzhou 450011, Henan, China 2 Institute of Future Farming Systems, School of Medical and Applied Science, CQUniversity, Rockhampton, QLD 4702, Australia 3 School of Engineering and Technology, CQUniversity, Rockhampton, QLD 4702, Australia 4 Department of Chemical and Process Engineering, University of Sheffield, Mappin Street, Sheffield S1 3JD, UK