Canadian fertilizer giant PotashCorp, in a parting shot as it ditched an $8.9bn bid for K+S, warned of rough conditions ahead in the potash market.
Jochen Tilk, the PotashCorp chief executive, cautioned the board of Germany's K+S that "storms may be coming your way", in a letter confirming the withdrawal of a proposed E41-a-share bid.
"As we are sure you are aware, macroeconomic headwinds — including concerns about global economic growth projections and foreign currency volatility in a number of key regions — have impacted the broader equity and commodity markets, and potash has not been immune," said Mr Tilk.
Mr Tilk said that global potash demand, long-term, "will grow with an increasing population and improved nutrition", echoing comments made in a PotashCorp market outlook last week.
But the PotashCorp head warned that the coming years may be "more challenging because of the macroeconomic environment and increased competition".
Russia, a key potash exporter, has seen its currency fall sharply against the dollar.
This will allow Russian exporters to accept lower dollar-denominated prices for their product.
And the currency effect comes at a time of reduced supply discipline, after the breakup of the Belarusian Potash Company, a price cartel made up of Russian group Uralkali, and its regional competitor Belaruskali, in 2013.
The end of the cartel has already seen aggressive production from Belaruskali.
And PotashCorp noted that more supplies from Russia could be on the way, citing the "commencement of production of Eurochem's mines in Russia".
PotashCorp is well placed to face down a more competitive market, having recently completed expansions of its facilities in Rocanville, and New Brunwsick, giving the company ample room to ramp up production.
Meanwhile, K+S has been developing its own North American capacity, in the form of the Legacy project, the first greenfield potash project to be launched in Saskatchewan in more than 40 years.
The proposed merger would have the Legacy project under the Canpotex potash exporting cartel, of which PotashCorp is a key member.
Canpotex also comprises Canadian potash miner Agrium and the US group Mosaic.
Mr Tilk noted that that one possibility offered during merger talks was potash swaps between Legacy and PotashCorp's facilities in New Brunswick "to reduce future freight costs and serve our customers more cost-effectively".
K+S's German mines have a high cost of extraction compared to facilities in the former Soviet Union and North America.
That question of profit margins was key to the failure of the takeover bid, as concerns grew that jobs would be lost due to mine closures.
Mr Tilk noted that the PotashCorp takeover offer had included assurances of "no business-related employee terminations or mine closures in K+S' German operations beyond K+S' current strategy for five years".
However, K+S, separately on Monday, disputed that assertion, saying that "the job and site commitments by PotashCorp included such far-reaching restrictions that commodity production would not have been secured in Germany".
The German group added that it was "expecting further tangible growth in the business units potash and salt in the medium-term.
"Despite the current weakness of the potash markets, K+S still expects significant sales and earnings growth this year."
By William Clarke