* CBOT December corn settled down 4-3/4 cents at $3.43-1/4 per bushel after dipping to $3.42-1/2, a contract low.
* Late on Monday, the US Department of Agriculture said the US corn harvest was 9 percent complete, near an average of analyst estimates for 10 percent and ahead of the five-year average of 6 percent.
* Soybean futures slipped after top global soy buyer Beijing added $60 billion of US products to its import tariff list in retaliation for President Donald Trump's planned levies on $200 billion worth of Chinese goods.
* The tit-for-tat measures are the latest escalation in an increasingly protracted trade dispute between the world's two largest economies.
* Private analytics firm Informa Economics projected that US corn plantings would rise to 93.044 million acres in 2019, trade sources said, compared to the USDA's 2018 figure of 89.1 million acres.