Shares in European fertilizer groups took a new lurch down after Terra Industries, the US nitrogen group, added a Louisiana plant to the long list of mothballed plants "due to current market economics".

The US-based group said the site, which has capacity for 500,000 tonnes of ammonia per year, would be closed until market conditions improve.

The shutdown comes a week after Germany's K+S knocked more than $9bn from the market value of leading fertilizer makers by revealing "extraordinarily weak sales" and the idling of a 2m tonnes in potash capacity.

Indeed, investors in European fertilizer proved especially nervous over the Terra idling. While Terra closed down 1.1% at $25.98 in New York, Uralkali, the Russian potash group, ended down 5.1% at 99.00 roubles in Moscow.

K+S shares recovered from a fall of nearly 6% to close down 3.3% at E41.00 in Frankfurt, while shares in Yara, the Norwegian nitrogen giant, closed down 3.6% at NKr182.50 in Oslo after, again, falling 6% in early afternoon deals.

Many Western nitrogen companies have fared relatively well during the current slump in fertilizer use, thanks in part to the nature of the nutrient, which is relatively quick to leach from the soil, and the fall in natural gas prices.

Former Soviet states, where gas prices have remained relatively high, have swallowed the lion's share of global nitrogen production shutdowns, which totalled roughly 13m tonnes last month, data from PotashCorp shows.

About 5% of world ammonia capacity was offline and 4% of urea capacity, PotashCorp, the world's biggest fertilizer group, said.

For phosphates and potash, the other major fertilizer groups, curtailments had reached about 20% of global capacity.