Farmers have won two big victories against the potash giants.

Fertilizer bosses such as Bill Doyle – whose PotashCorp has announced its third profits warning in five months - will eventually find the market turning their way after a torrid year.

Growers cannot hope to avoid it for ever and still expect decent crop yields.

But that does not mean farmers have wasted their time in calling his bluff on high prices.  

No cartel

First, they have demonstrated that the potash industry is not as invulnerable as it had thought.

But it has proved unable to use this market squeeze to its advantage. When buyers went on strike, it was producers who cracked, notably the Russians in offering cheaper potash to India in July.

Potash groups may think twice again before trying again to keep potash prices high while those of the other main nutrients, nitrogen and phosphate, crumble.

Yield benefits?

Indeed, the second benefit farmers have demonstrated is that potash applications are not always necessary for huge yields.

It is an unhappy co-incidence for the potash companies that America is on track for record US corn yields and soybean production in a season in which potash applications have been, at about 7,000 tonnes, more than 1,000 tonnes lower than any in other season in at least three decades.

Farmers will not be for ever able to pull off the trick of taking away potash, in form of harvested crops, without replacing it.

But it is a reminder to many growers that can, every so often, save themselves a packet by taking a potash holiday.

Shares lag

The industry's woes have not been lost on investors. While all fertilizer groups suffered, as farmers reined in spending when crop prices headed south last year, potash groups have fared particularly badly.

Shares in Canada's PotashCorp, for instance, the biggest potash group, have risen by only 11% this year, less than half the rate of those in Norway's Yara, the top-ranked nitrogen group. Stock in K+S, Europe's main potash concern, has fallen 4%.

PotashCorp would be worth more than US$4bn more if its shares had risen in line with Yara's this year.

That's something Mr Doyle - and his shareholders - might like to think about the next time he decides to try flexing his market muscle.