"It is not an exact science but when we look at the fields, it looks like it is going to be a big crop," said John Reifsteck, a corn and soybean farmer in Champaign, Illinois, a Midwest farm belt state.

Reifsteck estimated his corn crop could be as much as 15 percent higher than last year's.

The US Department of Agriculture is forecasting record crops this year for corn and soybeans, the two largest US crops in terms of production. Unless there is a devastating freeze or torrential rains before the harvest ends, corn production is projected at 366 million tonnes and soybeans at 106.5 million tonnes.

Handling all this production will be complicated. According to Arthur Neal, a USDA transportation and marketing official, about 3.5 percent of the crops, equivalent to 762,600 truck loads, cannot be kept in permanent storage structures like silos -- the highest share since 2010.