Chicago Board of Trade corn futures drifted lower on Wednesday, following wheat, as profit-taking sent prices falling after four days of gains, traders said.

The market is growing increasingly skeptical Chinese export prospects for US supplies at the volumes that Washington has promised - particularly wheat and corn, traders said.

CBOT March corn settled down 3 cents at $3.87 per bushel. Traders said the corn market remains underpinned by easing US-China trade war tensions after the two sides agreed to a Phase 1 deal last week and a proposed increase in export taxes in Argentina, a key global corn supplier.

Chinese commodities trader COFCO, Brazilian grains group AMaggi and a Shell-Cosan joint venture are working on plans to build their first corn ethanol plants in Brazil, according to their suppliers. Traders also said that reports of a weakening cash basis among Midwestern interior grain elevators and processors is a sign that, at least for now, the local demand for grain is somewhat flat going into the holidays.