Carolyn Hedley1, Jagath Ekanayake1Alison McCarthy2,
2 National Centre for Engineering in Agriculture, University of Southern Queensland, Australia
Trials have been conducted on commercial farms to investigate the impacts on crop yield when irrigation applied from sprinkler irrigation systems is varied to different soil zones according to differences in their moisture status, with the aim of saving water. Soil variability was initially quantified by electromagnetic survey, ground-truthing and laboratory analyses of soil water-holding properties; and management zones were delineated for the irrigation prescription maps. Replicated plots within each soil management zone received one of two treatments: uniform rate irrigation (URI) or variable rate irrigation (VRI). The yield impacts of VRI were neutral, and water savings were between 27 – 55 mm when irrigation was reduced to soils with adequate plant available water and excluded from wet, poorly draining soil zones.