Soybeans declined on Tuesday falling from the strongest level in nearly two weeks as U.S. farmers accelerated harvesting and as crop outlook in Brazil, the world's biggest producer, was raised amid rains in the country. January soybeans futures slipped 0.5% to $12.9425 a bushel in the CBOT and were traded at $12.9775 as of 11:07 a.m. Singapore time.