US grain futures closed lower on the Chicago Board of Trade Thursday, as the dollar weakened, but early gains evaporated through the day. Corn was off 8 1/4 to off 13 1/4, soybeans were off 38 1/2 to off 48, wheat was off 8 to off 19 1/4 and oats were off 3 1/4 to off 3 1/2. Corn dropped slightly with early gains checked by realization recent rains provided some relief from the drought. Wheat futures also gained early, but followed corn to moderate losses. The soybean markets took sharper losses after storms swept across the Midwest providing the first substantial wetting in weeks. The prices: Corn: Sep 7.81 1/4 off 13 1/4, Dec 7.76 1/4 off 11 3/4, Mar 7.73 1/4 off 9 1/4, May 7.68 1/4 off 8 1/4. Soybeans: Aug 16.55 3/4 off 38 1/2, Sep 15.96 1/2 off 44, Nov 15.67 1/2 off 48, Jan 15.55 off 43 1/2. Wheat: Sep 8.84 off 19 1/4, Dec 8.97 1/4 off 17 3/4, Mar 9.00 1/4 off 9 3/4, May 8.82 1/2 off 8. Oats: Sep 3.69 1/2 off 3 1/4, Dec 3.72 3/4 off 3 1/4, 3.77 1/2 off 3 1/2, May 3.81 1/4 off 3 1/2.