* Wheat curbed by steady U.S. crop rating

* Chances for improved field weather also cap grain prices

* Russian grain estimates above expectations

* Investors adjust positions before crop, economic data

(Updates prices, updates with analyst quotes, weather, Russia wheat estimates, Brazil soy estimates, changes byline, previous dateline PARIS/SINGAPORE)

CHICAGO, April 9 (Reuters) -

Chicago Board of Trade (CBOT) wheat futures turned lower on forecasts of bountiful crops in Russia and


, while improving U.S. weather ahead of the spring planting season pressured corn and soybeans, traders said.

Traders spent much of the session adjusting positions ahead of

U.S. inflation data

on Wednesday and the U.S. Department of Agriculture's monthly

supply and demand report

on Thursday.

Traders were also prepping for Brazilian agency Conab's monthly national crop forecasts and the March U.S. consumer price index on Wednesday.

Forecasts for improved precipitation in the Plains next week and an easing of heavy rain in the southern Delta zone reduced concern about weather-related stress to wheat crops and delays to corn planting.

"We're going to get some rain on the plains in Kansas that might be weighing on the market a little bit," said Brian Basting, an analyst with Advanced Trading.

U.S. Department of Agriculture (USDA) crop progress figures released after Monday's market close tempered concerns about dryness in the U.S. Plains, with the good/excellent rating for U.S. winter wheat at 56%, the highest for this time of year since 2020.

News that commodity analysis firm Argus raised estimates for Russian wheat production also weighed on wheat futures, said Jim McCormick of AgMarket.net.

"The big problem is there's a lot of wheat in the world."

Most-active CBOT May wheat futures was down 1.19% at $5.59 a bushel at 1621 GMT. CBOT soybeans was 0.47% lower at $11.76 a bushel, and corn was down 0.75% at $4.32-1/4 a bushel. (Reporting by Renee Hickman in Chicago. Additional reporting by Gus Trompiz in Paris and Naveen Thukral in Singapore; Editing by Sherry Jacob-Phillips, Shweta Agarwal and Richard Chang)