America's corn harvest is to set a record, if not by as much as had been expected, Informa Economics said, as investors prepared for a set of US data billed as a "fireworks show".

Informa, whose estimates are seen as among the most influential from private analysts, pegged the US corn harvest at a little under 13.8bn bushels, nearly 700m bushels ahead of the all-time high set two years ago.

The figure was 130m bushels below Informa's last estimate. However, it remained nearly 600m bushels ahead of the estimate in last month's flagship US Department of Agriculture Wasde briefing.

USDA analysts are to unveil fresh crop figures on Tuesday in the light of their revelation last week that America's farmers sowed far more corn than had been thought, with inventories left over from last week's harvest are bigger than had been thought too – estimates which sent prices tumbling.

Given the number of variables to predict, including a boost to exports prompted by the lower prices, Tuesday's data is viewed by many analysts as particularly difficult to predict.

"The Wasde report on Tuesday will be a fireworks show for sure so do not get ahead of yourself today," Matthew Pierce at PitGuru said.

Soybean forecasts

Informa's forecasts for the acres that US farmers will harvest was, at 84.7m acres, close to a USDA estimate updated last week.

Informa was a little less upbeat than the USDA, by 0.3 bushels per acre, on the American soybean yield, which it pegged at 43.1 bushels per acre, reflecting a below-average start for the crop

With harvested acreage put in line with the USDA at 74.3m acres, this put the US soybean harvest at 3.2bn bushels, 280m bushels below the last official forecast.

Stocks implications 

Other observers releasing estimates included Jerry Gidel, at broker North America Risk Management Services, who estimated that the USDA will on Tuesday lift its corn harvest estimate by 270m bushels to nearly 13.5bn bushels

That is 470m bushels more than the current official estimate, besides being above the psychologically important 1bn-bushel mark, if, representing only a month's supply, still tight by historical standards.

Mr Gidel estimated the soybean production figure at 3.22bn bushels, and ending stocks for 2011-12 at 163m bushels, a drop of 27m bushels from the latest USDA figure.