Uralkali has warned of the threat posed by the devaluation of the Chinese currency to potash demand, while its shares rise on news of a $1.3m buyback.
The Russian potash giant sees 2015 demand for the plant nutrient at 58m tonnes, down from 63m tonnes last year.
The guidance came as Uralkali launches another massive share buyback programme, increasing the possibility of the group's delisting from the London Stock Exchange (LSE).
Uralkali announced a tender offer for up to 14%, or $1.3bn of its shares at $3.2 a share, and for its London-listed global depository receipts, a proxy for equity, at $16 a share.
The share buyback may force the delisting of Uralkali from the LSE due to liquidity requirments imposed by the exchange, a move which some believe would open the way for the group's takeover by Uralchem.
Uralkali has previously stated that it would be forced to delist from the LSE if its free-float, the proportion of shares that are available on the exchange, fell below 25%.
The delisting of Uralkali could clear the way for the takeover of the company by Uralkali, a move which has been rumoured to be under consideration, but never commented on by either party.
Last month Vedomosti, a Moscow newspaper, carried reports from sources close to the companies that Uralchem was poised for a takeover of the fertilizer group.
Uralchem, a Russian chemical company, already owns 20% of Uralkali's shares.
The chemical group refused to relinquish them in an earlier share buyback, announced in June, which saw the Uralkali tender for $1bn of its own shares, with limited success.
In half-year reports issued on Tuesday, Uralkali reported that its revenues over the first six months of 2015 fell by 9% to $1.56bn.
"The potash market was relatively weak in the first half of 2015," Uralkali said, citing low agricultural commodity prices and thick global inventories.
But the group's net profit rose 50% compared with same period last year, to $556 million, thanks largely to currency fluctuations over same period, which boosted rouble denominated receipts.
Uralkali painted a muted picture for potash demand over the next six-months, flagging weaker currencies in key buying countries.
Global potash markets are priced off supply contracts signed between Chinese and Indian buyers and a number of large suppliers.
Until 2013 these contracts were a duopoly between the North American exporting cartel Canpotex and the former Soviet Union cartel BCP.
In 2013 BCP split, thanks to a dispute between its component companies Uralkali and the Belarusian supplier Belaruskali, causing potash prices to fall as supply discipline weakened.
Uralkali reported that deliveries to China and India had been in line with the agreed 2015 contracts so far this year.
But the group warned that Chinese volumes might suffer thanks to the introduction of a retail tax on fertilizer in China, as well as depreciation of the Chinese currency, which makes imported fertilizer less affordable for farmers.
Uralkali also raised questions about prospects for Indian demand over the rest of the year.
"The depreciation of the Indian rupee against the US dollar, subsidy issue, and the monsoon deficit may affect importers and may influence the full-year potash import figure," Uralkali said.
The company pegged full year Indian demand expectations at 4.3m-4.5m tonnes, compared to 4.5 million tonnes last year.
Uralkali reported that demand in Southeast Asia and Oceania was "relatively strong," but saw a limited price upside due to "local currency weakness, low palm oil prices, and competitive pricing from suppliers".
Full year potash demand for the region was forecast at 9.5m-9.6m tonnes, compared to 10.2m tonnes last year.
And demand from Europe, the Middle East and North Africa was forecast at 11.0m-11.1m tonnes compared to 12.3 million tonnes last year.
In Latin America the company pegged full year demand at 9.8m-10.0m tonnes in 2015 compared to 11.8m tonnes last year, noting the sharp fall in the Brazilian currency, as well as the lack of access to farm credit.
North American demand was also seen behind last year, thanks to a delayed planting season, high potash price volatility because of strong competition, and lower corn planted acreage.
North American potash demand was forecast to fall 14-16% year-on-year to 8.6m-8.7m tonnes in 2015.
Uralkali GDRs were trading up 3.8% in London at $15.110 a share in afternoon deals.
By William Clarke