At the same time, planting delays in the US Midwest could prompt farmers to shift some acres intended for corn to soybeans, potentially adding to burdensome supplies of the oilseed. Soybeans can be planted later than corn.
Wheat and corn futures rose, bouncing from contract lows set in both grains.
As of 1:00 p.m. CDT (1800 GMT), Chicago Board of Trade July soybeans were down 4-1/2 cents at $8.04-3/4 per bushel after falling to $7.91, a contract low and the lowest for a most-active soybean contract on a continuous chart since December 2008.
CBOT July wheat was up 14 cents at $4.38-3/4 a bushel, rebounding from a contract low of $4.18-1/2, and July corn was up 4-3/4 cents at $3.56-1/2 a bushel, bouncing after a contract low of $3.43.
Soybeans fell after the trade tussle between the world's top two economies intensified on Friday, when the United States increased tariffs on $200 billion worth of Chinese goods, blaming Beijing for reneging on earlier commitments.
Trump also ordered US Trade Representative Robert Lighthizer to begin imposing tariffs on all remaining imports from China, which would affect a further $300 billion worth of goods.
Beijing on Monday said that China would never surrender to external pressure but stopped short of announcing how it would respond to US tariff pressure.
The US Department of Agriculture's monthly supply/demand report on Friday, meanwhile, also cooled price sentiment by projecting bigger than expected domestic supplies of soybeans, corn and wheat.
"Beans have no light at the end of the tunnel, other than the fact that funds are short," said Matt Connelly, analyst at the Hightower Report in Chicago.
The USDA last week raised its forecast of US 2018/19 soybean ending stocks by 100 million bushels, to 995 million bushels, a record high. The figure could rise if Chinese buyers cancel cargoes of US soybeans they have bought but have not yet shipped.
"If this thing drags out and everyone plays hardball, you are going to get more cancellations, or at least they will defer to 2019-20. And South America has got a big crop," Connelly said.
Wheat futures bounced off contract lows after the USDA reported weekly US wheat export inspections of 842,418 tonnes, topping trade expectations.
Uncertainty about US corn and spring wheat acreage lent support, given wet and cool weather that has slowed planting in the western Midwest and northern Plains.
"That (wheat export inspections) number was a little positive, and there is a lot of head-scratching about what the actual acres will be," Connelly said.
Ahead of the USDA's weekly crop progress report due later on Monday, analysts on average expected the government to show US corn planting progress as 35pc complete, roughly half the five-year average of 66pc.