Poor export demand caused basis levels at the U.S. Gulf of Mexico to continue to weaken Friday, while interior basis levels for grains and oilseeds has been mostly steady.

Basis levels fell by one to five cents per bushel for soybeans at grain elevators near the coast in Louisiana and Texas, according to U.S. Department of Agriculture data. Basis is the difference between cash and futures market prices.

Basis levels had also weakened Thursday at the Gulf, as poor soybean export sales have highlighted weak demand. Export sales for corn have also been weak, as Asian buyers have recently opted for corn from Brazil or Ukraine, but corn Gulf basis levels were unchanged Friday.

Meanwhile, interior basis levels have been mostly steady, particularly for corn and soybeans, as farmers are either unwilling or too busy with harvest to sell grain, analysts said.

According to a national cash grain index maintained by the Minneapolis Grain Exchange, prices for spot-month Chicago Board of Trade corn futures settled 20 cents above the average cash price Thursday, while soybean futures were at a 55 1/2-cent premium. Basis levels in both instances were unchanged from the day before.