U.S. corn futures hovered around their lowest in around a month on Wednesday, but with some bargain-buying support after a dramatic fall of almost 6 percent on Tuesday caused by improving U.S. crop weather.

Wheat firmed on concerns over possible quality damage to the Black Sea region crop, while soybeans rose on strong export demand for U.S. supplies, especially from China.

The Chicago Board of Trade July corn contract corn was down 0.1 percent at 3.95-1/2 a bushel at 1017 GMT, its lowest since May 24.

Corn's 5.9 percent drop on Tuesday was the biggest fall for a spot contract since September 2013 as forecasts for much-needed rain this week in U.S Midwest grain belts eased worries about dryness, sparking heavy investment fund selling.

July soybeans gained 0.1 percent to $11.35-1/4 a bushel and July wheat added 0.6 percent to $4.61-1/4 a bushel. Corn was still moving in and out of positive territory in European trade on Wednesday.

"The corn market is weighing up support coming from bargain-buying after Tuesday's sharp price fall coupled against a continued bearish mood caused by the positive condition ratings and better weather outlook for U.S. crops," said Frank Rijkers, agrifood economist at ABN AMRO Bank.

Commodity investment funds had taken a massive net long position in corn after disappointing South American harvests and uncertainty about U.S. crop prospects.

But the U.S. Department of Agriculture's crop progress report on Monday rated 75 percent of the U.S. corn acreage in good to excellent condition, unchanged on the week. Analysts had expected a decline in ratings.

Soybeans were lifted by news on Tuesday of exporters selling 132,000 tonnes of U.S. soybeans to China.

"Soybeans are being underpinned by news of yet more U.S. soybean and soyoil export sales to China," Rijkers said. "Despite the worries about the state of China's economy, Chinese import demand for soybeans has remained enormous in past days and weeks and appears to show no signs of slackening."

"Wheat is also being supported by concern about rain causing quality damage to crops in Russia and Ukraine, both major players in the world wheat export market. Any reduction in their crop quality could shift export demand to other origins."

Rain has reduced protein levels in Russian wheat and raised concerns over fungal disease while also reducing the proportion of milling wheat in Ukraine.