Shares in Black Earth slumped by more than 6% after the Russian farm operator revealed grain yields as much as 50% below last year because of the country's worst drought on record.

The group said that its winter wheat harvest had come in at 2.0 tonnes per hectare, down one-third on last year's. Production fell to 165,000 tonnes from more than 290,000 tonne in 2009.

The spring wheat yield also fell by one-third, to 1.4 tonnes per hectare, while the barley result had more than halved, also to 1.4 tonnes per hectare.

"Severe weather conditions, with average temperatures far above normal, as well as very little rainfall, has affected this year's grain harvest," said Black Earth, which earlier in the year warned over crop losses to Russia's cold winter.

'Very volatile' 

The company also flagged the higher crop prices resulting from the poor harvest, noting year-on-year increases of 21-45% in prices, depending on quality.

Malting barley prices had soared by 74%.

However, the company failed to detail the implications to its results of the "very volatile" prices, nor comment on Russia's export ban, also announced on Thursday.

Agrimoney.com was unable to reach a company spokesman for further details.

Black Earth shares closed down 6.1% at SKr23.10 in Stockholm.