CHICAGO (AP) _ Grain futures were mostly lower in early trading Tuesday on the Chicago Board of Trade. Sept. corn was off 0.75 cent at $5.14 a bushel. Sept. wheat was up 15.25 cents at $7.72 a bushel. Sept. oats was down 7 cents at $3.40 a bushel. Sept. soybeans lost 0.75 cent at $12.74...