PARIS/SYDNEY: Chicago soybeans rose for a second day on Wednesday as a decline in US crop ratings kept attention on harvest risks while a latest export sale to China boosted demand sentiment.

Corn was little changed, also underpinned by Midwest weather risks and Chinese demand but capped by ample inventories and uncertainty over the economic impact of a coronavirus epidemic.

Wheat ticked higher as reduced production estimates for northern hemisphere harvests supported prices.

The most active soybean futures on the Chicago Board Of Trade were up 0.5% at $8.82-1/4 a bushel by 1212 GMT.

The oilseed also drew support from a rally in Malaysian palm oil to a near five-month high.

US exporters sold 129,000 tonnes of soybeans to China for the 2020/21 marketing year, the US Department of Agriculture said on Tuesday.

"The USDA reported more export sales to China. While the sale's scale was routine, it does mean that the higher prices that prevailed last week were not discouraging buyers in China," said Tobin Gorey, director of agricultural strategy, Commonwealth Bank of Australia.

Soybeans had climbed to a two-month high last week before retreating to a near two-week low on Monday as rainfall eased harvest concerns.

But a decline in weekly crop ratings as published by the USDA after Monday's market close rekindled harvest concerns.

The USDA rated 68% of the US soybean crop as good to excellent, down from 71% previously, while putting 69% of the US corn crop as good to excellent, down from 71%.

CBOT corn futures were down half a cent at $3.33-1/4 a bushel.

Corn drew limited support from Tuesday's USDA announcement that China had booked its biggest single-day purchase of US corn on record at 1.762 million tonnes.

CBOT wheat were up 0.4% at $5.28-3/4 a bushel, as investors assessed a steady drop in estimates for this year's Russian harvest.