Robert M. Norton1, Graeme Watmuff2, Chris Dyson3, Mark Conyers4, Michael Bell5, Nigel Wilhelm3, Richard Bell6, Chris Dowling7, Charles Walker8 and Ken Peverill9, (1)International Plant Nutrition Institute, Oceania, Horsham, Victoria, Australia, (2)Geographic Web Solutions, Woodforde, Australia, (3)South Australian Research and Development Institute, Adelaide, Australia, (4)New South Wales Department of Primary Industries, Wagga Wagga, Australia, (5)University of Queensland, Gatton, Australia, (6)School of Veterinary and Life Sciences, Murdoch University, Murdoch, WA, Australia, (7)Back Paddock Company, Cleveland, Australia, (8)Incitec Pivot Fertilizers, North Shore, Australia, (9)K I P Consultancy Services P/L, Wheelers Hill, Australia