Global stocks of corn, wheat, rice and soybeans combined will hit a record 671.1 million tons going into the next harvest–the third straight year of historically high surplus, according to the U.S. Department of Agriculture (USDA).

USDA already expects 2016-17 global harvests to be the highest since its records started in 1960-61 at 340.79 million tons of soybeans, 1.049 billion tons of corn and 751.07 million tons of wheat. As a result, farmers across the globe are facing storage problems.  World stockpiles of corn and wheat are at record highs. From Iowa to China, years of bumper crops and low prices have overwhelmed storage capacity for basic foodstuffs.

Permanent storage in the United States can handle about 24.3 billion bushels–well short of the 25.9 billion bushels of wheat, soybeans and feed grains USDA said was piled up by the end of last autumn’s harvest. That overflow in the United States has prompted a rush for temporary storage. USDA has approved permits for more than 1.2 billion bushels of temporary and emergency grain storage–such as tarp-covered piles and open-air mounds.

In the United States, farmers facing a fourth straight year of declining incomes and rising debts are hanging on to grain in the hope of higher prices later. They may be waiting a long time as market fundamentals appear to be weakening as the world’s top grain producers ponder what to do with so much food.

The persistent glut is a striking contrast from the panic a decade ago, when severe droughts in the United States and Russia sent prices soaring. The shrinking supply forced big importers such as China to enact policies to encourage more domestic production and increase the volume of storage to improve food security. However, China abandoned that policy last year and is now selling off hundreds of millions of tons of old stocks.  Russia, too, is looking at exporting from state-held stockpiles, with storage stuffed after a record harvest in 2016.  A surge of Chinese and Russian exports would put even more downward pressure on prices in an oversupplied global market.

That means U.S. farmers will likely be producing more grain for less money. The USDA forecasts net farm income will fall 8.7-percent this year to $62.3 billion–the lowest level since 2009.

Storing grain gives farmers more control over when and how they sell, to avoid low harvest-time prices and to best take advantage of spikes in futures or currency swings. But with storage running short–and a mountain of grain to move ahead of summer or early autumn harvests–that control is slipping away. Farmers with mounting bills, tight cash-flow, and nowhere to store crops may have to sell them, even if it means taking a loss.

In Kansas, farmers holding grains in silos are facing cash corn prices of $2.90 per bush, well below production costs of at least $4 a bushel. Some grain owners are renting airport tarmacs from decommissioned military bases, empty farm fields and parking lots to stash their corn as the situation becomes acute. Meanwhile, there are no signs of a slowdown in grain production.