U.S. soybean futures rose for a fifth session on Thursday, hitting an eight-month high, as strong demand from top importer China and short-covering by investors underpinned the market.

Corn edged up after rallying almost five percent in the past two sessions while, wheat gained for a third straight day.

Chicago Board of Trade (CBOT) most-active May soybean contract rose 0.4 percent to $9.59-1/2 a bushel, highest since Aug 12, 2015. Corn gained 0.1 percent to $3.74 a bushel, while wheat added 0.8 percent to $4.65 a bushel.

"There is strong upside move in soybeans," said Kaname Gokon at brokerage Okato Shoji in Tokyo. "China's demand is a key factor which is bullish for the market. We also have rainy weather in Argentina which is hitting the harvest and increasing demand for U.S. products."

China's March soybean imports climbed to 6.1 million tonnes, setting a record for the third month of the year as attractive hog breeding margins and flows of newly harvested supplies from South America lifted demand.

The data eased market concerns that a slower economic growth in China could cut the country's soybean purchases.

Heavy downpours have ruined the harvest of nearly 5 percent of Argentina's soybean farms and could damage even more of the 2015-16 crop if rains extend into the coming weeks.

At the same time, there are expectations of strong domestic demand in the United States.

The National Oilseed Processors Association's monthly soybean crush report due on Friday should show the U.S. crush for March at 156.248 million bushels, up 6.9 percent from February, according to a Reuters poll of seven analysts.

Commodity funds hold a hefty net short position in CBOT corn and soybeans, leaving the markets vulnerable to short-covering at a time when the U.S. planting season is just getting started.

Funds were heavy net buyers of CBOT corn and soybean contracts on Wednesday, with estimates in a wide range following high-volume trade, traders said.

Trader estimates of fund buying in corn ranged from 20,000 to 35,000 contracts, and in soybeans from 15,000 to 22,000 contracts.

The U.S. Department of Agriculture has projected that U.S. farmers will expand corn plantings in 2016 by 6 percent, to 93.6 million acres. But soybeans could win back some acres after rallying to an eight-month top.

Forecasts for a record winter corn crop in Brazil look overly optimistic after summer rains ended sooner than expected, which could prolong the country's recently aggressive imports of the grain and even trim the area planted to soybeans in September.