TORONTO (Reuters) - The rush of mergers in the potash sector this year has lifted shares of Canadian-listed explorers, but the rally may say more about wishful thinking of investors than fundamentals of the fertiliser trade.

With major expansions by established producers under way and some big new projects waiting in the wings, junior miners may never attract the hot bids envisioned by the speculators who have run their share prices up this year.

BHP Billiton’s ill-fated $39 billion bid for Potash Corp, coupled with the buyout of juniors Athabasca Potash and Potash One, have whetted investor interest in producers of the crop nutrient.

Shares of explorers Western Potash, IC Potash , Amazon Mining, Allana Potash, Encanto Potash and Passport Potash have all risen about 100 percent or more during 2010.

While some juniors may become targets, most are still a long way from attracting bids. Few have advanced projects far enough or mitigated risks to the point of wooing buyers.

Most do not come close to falling into Potash One’s category. Salman Partners analyst Jaret Anderson points out its Legacy project had a feasibility study and environmental permits in place before the company attracted a $430 million bid from Germany’s K+S AG last month.

“None of the other projects have these sorts of advantages, not to say that they can’t get there, but it’s just going to take some time,” Anderson said.