DES MOINES, Iowa (AP) — The U.S. Department of Agriculture on Thursday slightly lowered its projection for the nation's corn crop for a fourth straight month, reflecting worse-than-expected news about the actual impact of this year's withering drought from the farmers busy harvesting their fields.

The USDA estimates that farmers will harvest 10.71 billion bushels of corn this year, which would be the smallest amount since 2006. Last month's estimate was 10.73 billion bushels.

Crop estimates change as fields are harvested and farmers get a better sense of how the weather affected yields. The U.S. has been experiencing one of its worst droughts in decades, and conditions have been particularly harsh in many of the key Midwest and Plains farming states.