U.S. corn and soybean futures descended to fresh three-year lows on Wednesday, with a rise in short covering as traders anticipate reports from the U.S. Department of Agriculture and Statistics Canada.

Chicago corn prices slipped, as traders observed weather charts pointing to a hot, dry spell in Argentina that is expected to be followed by widespread rain in the coming days. In addition, the anticipated rain in major Brazilian growing areas is contributing to expectations of abundant soybean supplies.

Corn Control for March delivery on the CBOT (C_1:COM) declined by -0.9% to $4.34 3/4 per bushel, while March soybeans (S_1:COM) settled at -0.8% to $11.89 3/4 per bushel. Conversely, wheat (W_1:COM) for March delivery rose by +1% to $6.00 3/4 per bushel.

ETFs: (NYSEARCA:CORN), (NYSEARCA:SOYB), (NYSEARCA:WEAT), (DBA), (MOO)

The market movements indicate a shift in focus towards forecasts of an excessive grain and oilseed production this year, as indicated by Consus Ag Consulting’s Karl Setzer to Reuters.

“Currently, we are not facing a low-demand market,” said Setzer. “We are encountering a supply issue. We are over-producing beyond the world’s needs.”

Traders will be particularly attentive to the Brazilian agency Conab’s update of the country’s official production estimates, Setzer mentioned, following the USDA’s report last month of larger than expected Brazilian crops, and augmented U.S. yield and production levels for the recently harvested crop.