Infrastructure shortages and the growth of livestock production and may limit the ability of the Black Sea states to fulfil their potential for replacing the US as the "breadbasket of the world".

Kazakhstan, Russia and Ukraine look set to raise wheat exports by one half to more than 50m tonnes by the end of the decade, overtaking America, the biggest exporter since World War II, a report from the US Department of Agriculture said.

America's share of world wheat exports will fall to 16% from an average of 24% over the last decade, with Canada and Europe, although not Australia, also set to lose ground.

However, such forecasts could fall foul of the weaker wheat prices which a jump in Black Sea harvests may cause, or of a dearth in transport and elevator space, especially in the outlying regions whose adoption of grains would be crucial to raising output.

Furthermore, attempts to reverse a dramatic decline in livestock production since Soviet times, when the region imported grain and oilseeds, may soak up domestically considerable quantities of grain.

'Uncertainty exists'

"Of all the major grain-producing countries, Russia, Ukraine, and Kazakhstan appear to have the most potential to substantially increase wheat production and exports," the USDA said.

"Yet uncertainty exists as to the degree to which the three former Soviet Union countries will increase their wheat exports."

The briefing also flagged doubts over the nations' reliability as exporter after, during the 2006-08 spike in farm commodity prices, attempting to restrict or ban shipments.

"These uncertainties are likely to mitigate, though not reverse, the growing importance of Russia, Ukraine, and Kazakhstan as providers of wheat to the world."

Yield improvements 

Increased sowings provided much of the scope for the Black Sea states to raise production, with plantings still behind those in the Soviet period, when indeed grains were restricted largely to poorer quality land.

However, yields will also rise, helped by increased use of fertilizer and the expansion of efficient corporate farms. Russian yields are expected to jump by 20% by 2019, and those in Ukraine by 17%.

Improvements over the past decade had also been helped by benign weather and a switch to autumn sown wheat, which typically yields more than spring-planted grain.