Soybeans continued rallying for a fourth straight weekly gain amid speculations that a strengthening economy may boost demand for fuel and food.

Crude increased to $116.97 a barrel on signs of economic growth.

Soybean futures for May delivery increased by 0.8 percent or 10.5 cents to $13.77 a bushel on the Chicago Board of Trade.

The U.S. Department of Agriculture forecasted production of biofuels using soybeans to increase by 56 percent this year compared to 2007.

A report from the Census Bureau showed that production of Methyl esters from soybean oil, used to make diesel fuel, surged 84 percent to 290.1 million pounds in February compared to last year.

Soybean oil futures for July delivery gained 0.3 percent, or 0.16 cent to 61.74 cents a pound on the Chicago Board of Trade.

The National Biodiesel Board said the U.S. biodiesel production increased by 80 percent to 450 million gallons in fiscal 2007 from last year.

The gain of soybean prices was also attributed to speculation that increasing global demand for U.S. soybeans will reduce reserve inventories.

The USDA forecasted stockpiles as of Aug. 31 to fall to 160 million bushels, 72 percent less than 574 million last year.