* More rains likely this week in Brazil, seen aiding soybean crop
* Growing concern about grain, oilseed demand weighs on futures
* Traders adjusting positions ahead of U.S. supply-demand reports
DES MOINES, IOWA, Jan 10 (Reuters) - Chicago soybean futures fell on Wednesday, shedding gains from the previous session, with forecasts of more rain in Brazil this week likely to further improve the maturing oilseed crop, plus there are growing concerns about demand.
Recent rains have eased concerns over dryness, which had been threatening soybean crop yields in Brazil, the world's top exporter of the oilseed.
Corn futures were steady to up, as investors in agricultural markets adjusted their positions ahead of a monthly report on global supply and demand, slated for Friday.
Traders are also expecting market guidance to come from this Friday's USDA quarterly U.S. grain stocks report, and data on how much crop may be held by U.S. producers on their farms.
Wheat futures were steady to mixed.
Large parts of southern and eastern Australia saw above-average rainfall in December, causing flooding in some areas but helping many farmers, while western areas remained parched, the country's weather bureau said on Tuesday.
The most-active soybean contract on the Chicago Board of Trade (CBOT) was down 0.52% at $12.42 a bushel as of 1633 GMT.
Wheat was down 0.33% to $6.08 a bushel, while corn was up 0.27% at $4.60-1/2 a bushel.
Brazil's crop agency Conab slashed the country's soybean crop forecast on Wednesday, but said it still expects it to come in slightly higher than last season's record output of 154.6 million metric tons.
Meanwhile, traders have growing concerns about export demand, as it has been weeks since the U.S. Department of Agriculture (USDA) has reported a flash sale on corn or soybeans, said Karl Setzer, partner at Consus Ag Consulting.
"Last week, we saw China purchase seven vessels of soybeans from Brazil", where prices are lower than in the U.S., Setzer said. "But to meet their expected demand, China would need to be buying seven vessels a day. What the market is realizing is Chinese demand isn't there right now." (Additional reporting by Naveen Thukral in Singapore and Sybille de La Hamaide in Paris; Editing by Sherry Jacob-Phillips, Jan Harvey and Jane Merriman)
