Talk of the minerals town this month, and perhaps for a while longer, is BHP Billiton Plc’s $39bn. bid for the world’s largest potash producer, Potash Corp. of Saskatchewan.The initial offer, immediately rejected by PotashCorp., could represent the biggest business transaction of the year, and in the minerals world, set to be larger than Rio Tinto’s acquisition of Alcan Inc. in 2007.Why potash? Why now?Well, the short answer could be “Why not?”Fertiliser minerals, in particular potash and phosphate, started to drift on to the radar of mineral developers and investors in the mid-2000s, as demand increased and prices followed suit. From a generally unattractive, relatively low priced commodity, potash soared to the heady heights of $900/tonne during 2007 to mid-2008. Soon everyone was seeking out potash and phosphate resource claims, and are still. Sure, the recession hit in 2008, demand fell and is now slowly recovering. Potash prices at present...