Crop scouts with the Farm Journal crop tour blanketed Iowa and six other upper Midwest states last week hoping to get a better handle on the yield potential of this year’s crops.

Farm Journal estimated the U.S. corn yield at 167 bushels per acre, based on samples pulled during the tour and other factors. The U.S. Department of Agriculture (USDA) earlier this month forecast a national corn yield of 169.5 bushels per acre.

Farm Journal’s soybean yield estimate, at 48.5 bushels per acre, also came in below the USDA estimate of 49.4 bushels per acre.

Iowa’s corn yield estimate landed at 183 bushels per acre, the second-highest among the seven states toured, despite very dry conditions in the western half of the state, Farm...