Iowa cropland values - sometimes seen as a harbinger of land values elsewhere - have dropped, partly because of concerns over tariffs and trade agreements, according to a new report.

Average statewide farmland values fell 1.7 percent to $6,844 from March through September, said the semi-annual report by the Iowa Chapter of the Realtors Land Trends and Values Survey.

At its peak in 2013, not long after the 2018-2012 agricultural boom, Iowa farmland sold for an average of $8,750 per acre, according to an earlier report.

The new report, which surveys farm specialists in land sales, management development and appraisals every six months, covers "bare, unimproved land with a sales price on a cash price."

Average land values fell across most of the state (north-central and northeast Iowa were the exceptions), and they they declined for high-, medium- and low-quality cropland.

The highest September 2018 land values were found in northwest Iowa, where high-quality farmland fetched an average of $11,029 per acre, compared with the statewide average of $9,237 for high-quality land, according to the survey.

But the the decline in the most recent six-month period follows a statewide increase of 2.9 percent from September 2017 to March 2018. Combined with the 1.7 percent decline, average Iowa statewide cropland values rose 1.2 percent from Sept. 1, 2017, to Sept. 1, 2018.

The new survey found these negatives for the land market:

• Continued poor commodity prices.

• Tariffs, world trade agreements.

• The potential for rising long-term interest rates.

It also found two positives for the land market: The amount of land for sale remain limited, although the volume of land for sale is beginning to increase; and the existence of 1031 Exchange (IRS tax deferrals for sellers of ag property).

The future direction of land values is uncertain and will depend on yields, commodity prices and the volume of land on the market, the survey finds, according to the report.

Farmers are the main buyers of Iowa farmland, although investors and recreational buyers are active, too, the report says.