* Q2 adj EBIT 157.3 mln euros vs Rtrs poll avg 103 mln euros
* Says potash prices have bottomed out
* Sees 2014 adj EBIT of 490-570 mln eur vs 513 mln poll avg
* Shares 2.4 pct lower, biggest DAX decliner (Adds CFO, trader and analyst comment, shares)
FRANKFURT, Aug 14 (Reuters) - German potash miner K+S beat quarterly earnings estimates on Thursday, helped by a one-off insurance payment, but its shares fell after a recent rally, given the uncertain outlook for fertiliser demand.
Second-quarter earnings before interest and tax (EBIT), adjusted for the effect of currency hedging, edged 3.3 percent lower to 157.3 million euros ($210.8 million) which included an insurance payout of some 30 million euros for a mining accident.
The core earnings by far surpassed the 103 million euro average estimate in a Reuters poll of analysts.
K+S said, however, that record harvests for some agricultural commodities were depressing prices and there was a risk farmers would try and cut costs.
Analysts and traders also pointed to the Russian ban on imports of fruit and vegetables from the European Union, in retaliation for Western sanctions over the Ukraine crisis.
They said the import ban could lower prices for the coming season and dissuade farmers from buying more fertiliser.
K+S shares were down 2.4 percent at 1357 GMT, making them the biggest loser in Germany's blue-chip index DAX, which was 0.4 percent higher.
"We remain concerned about the effect of the Russian ban on EU fruit and vegetables," Normura analysts said in a research note.
K+S finance chief Burkhard Lohr said, however, that the impact of lower agricultural produce prices on fertiliser demand could be mitigated if farmers decided to boost yields to offset price falls, rather than cutting costs.
POTASH PRICES STABILISE
Potash prices were continuing to stabilise after a slump in 2013, while regional demand had been good at start of the third quarter, Lohr told an analyst call.
The global potash market plunged into turmoil in July 2013 when Russian producer Uralkali quit a powerful sales alliance with Belarus' Belaruskali, causing higher output volumes and lower prices.
The average per-tonne price of K+S's potash products in the second quarter was 13.3 percent below the level a year earlier but up 2.4 percent from the first quarter, the group's financial report shows.
"Potash prices bottomed out at the beginning of this year but the lower average price in the potash business unit resulted in decreased revenues. Solid revenues in our salt business cannot completely make up for this," Lohr said.
The salt and potash mining company, formerly part of BASF , also issued a new 2014 outlook, saying it now saw adjusted EBIT falling to between 490-570 million euros from 655.9 million euros last year.
It had previously predicted a significant decline, and analysts on average forecast 513 million.
The one-off insurance payment was related to a mining accident last year.
Three workers died from a blast of carbon dioxide at the company's Unterbreizbach mine in the German state of Thuringia in October last year, and it took the company months to fully restore operations. (1 US dollar = 0.7464 euro) (Additional reporting by Jonathan Gould; Editing by David Clarke)