Corn and soybean markets continued their march higher last week after the U.S. Department of Agriculture (USDA) again lowered its 2020 yield estimates.

As a result, the USDA said U.S. stockpiles of corn and soybeans will shrink to their lowest levels since 2014 when this year’s crops are ready for harvest. At the same time, the average farm-gate price for corn and soybeans this marketing year will be the highest since 2013-14.

The USDA said 2020 corn yields came in lower than previously thought at 172 bushels per acre, down 2.2%...