Some American wheat farmers are not only going to lose money on every bushel they harvest this month, many won’t have a proper place to store it.

U.S. grain silos still hold surpluses from last year. Combined stockpiles for major crops — corn, soybeans, wheat and sorghum — are the biggest for this time of year since 1988. With demand slowing and output rising, space will get tighter, especially for wheat, which is the first one harvested. Some growers may dump grain in parking lots or vacant buildings.

“It will be the worst storage crunch in the 30 years I have been trading wheat,” said Michael O’Dea, a risk management consultant at INTL FC­Stone Inc. in Kansas City, Mo. “A lot of grain will end up in ground piles.”

While farmers expanded storage in recent years, that’s been undermined by global crop surpluses and a strong dollar. Once the world’s biggest wheat exporter, the U.S. saw its shipments in the year through Tuesday drop to the lowest since 1972. With inventories up 30 percent and expected to swell further, the price outlook is getting more bearish. Chicago futures tumbled for three straight years, and in February touched the lowest level since 2010.

The glut may only get bigger. Global supply, including production and inventories, will exceed consumption by the most ever in the year that ends in June 2017, with the harvest expected to be the second-highest on record, the International Grains Council said May 26.

For many growers, the slump means they are spending more to grow wheat than they can collect when the grain is sold, according to analysts at Societe Generale, which forecast Chicago wheat futures will average $4.52 a bushel in the third quarter, compared with $4.8675 now. Money managers have been betting prices will fall for almost 10 straight months.

But with so much left over from last year, growers from Texas to Nebraska probably will exceed local storage capacity by at least 15 percent, said Troy Presley, a grain merchandiser for Comark Grain Marketing LLC in Cheney, Kan.