Iowa farmland values have fallen more than 17 percent since peaking in 2013 as lower commodity prices, rising interest rates and trade disruptions contributed to the fourth drop in the past five years, according to the 2018 Iowa State University (ISU) land value survey.

This year’s survey estimates the average value of an acre of Iowa farmland at $7,264, down 0.8 percent ­— or $62 per acre — from a year ago.

“The key message from this survey is while we...