Nearly all soils in Western Australia were phosphorus (P) deficient when cleared for agriculture, but continual use of P fertiliser means acute deficiency in broadacre crops is rare, with the exception of very acidic and high PBI (phosphorus buffering index) soils, P deficiency is often transitory and compounded by dry soil with symptoms disappearing when topsoil is re-wet following rainfall.
Links
[1] http://www.pulseaus.com.au/