(Rewrites throughout with U.S. market open, adds quotes, updates prices, adds byline, changes dateline from JAKARTA)

CHICAGO, April 1 (Reuters) - U.S. grain futures fell on Monday as pressure from ample supplies partly unraveled steep gains late last week following a U.S. Department of Agriculture (USDA) report that projected lower-than-expected U.S. corn plantings.

Soybean futures eased along with lower corn and wheat in response to heavy global supplies and seasonally slowing U.S. export demand.

The stronger U.S. dollar added further pressure to grains as it makes dollar-denominated commodities costlier for importers holding other currencies.

Grain traders are turning their focus to spring planting weather after the USDA on Thursday pegged corn seedings well below trade expectations.

Some analysts and traders are expecting corn acres to increase with good spring planting weather, potentially boosting production when supplies are already ample.

"The U.S. weather outlook for the next two weeks is, for the most part, for above-normal temperatures and above-normal moisture. That's supporting the idea that we'll have good early planting," said Rich Nelson, chief strategist for brokerage Allendale.

Chicago Board of Trade (CBOT) May corn futures were down 6-3/4 cents at $4.35-1/4 a bushel by 11:44 a.m. CDT (1644 GMT) after last Thursday's USDA data triggered corn's strongest rally in more than eight months.

May soybeans were down 6-1/4 cents at $11.85-1/4 a bushel.

CBOT May soft red winter wheat fell 3 cents to $5.57-1/4 a bushel and May K.C. hard red winter wheat dropped 12 cents to $5.73-1/4 as traders anticipated improved winter crop ratings in a USDA report due after the close.

"Wheat is pricing in a much better good-to-excellent number for crop conditions," said Mike Zuzolo, president of Global Commodity Analytics.

Poor U.S. wheat export prospects also weighed on the market as rival suppliers continued to offer cheaper grain on the world market. (Additional reporting by Bernadette Christina in Jakarta; Editing by Mrigank Dhaniwala and Barbara Lewis)