* Soybeans fall despite strong exports

* Firm dollar weighs on wheat

* Corn supported by high input costs into 2022

CHICAGO, Oct 21 (Reuters) - Chicago soybean futures fell on Thursday after five straight sessions of gains, pressured by technical resistance and beneficial forecasts for rain in top export competitor Brazil.

Wheat eased from a two-week high hit earlier on Thursday as weaker crude oil prices and a firmer U.S. dollar offset tightening global supplies.

Corn edged lower, supported by a daily export notice and higher input costs heading into next year.

The most-active soybean contract on the Chicago Board of Trade (CBOT) ended 21-1/2 cents lower at $12.24 a bushel.

Wheat lost 8 cents to $7.41-1/4 a bushel, after hitting $7.52-1/2 overnight, its highest level since Oct. 7. Corn eased 7 cents lower to $5.32-1/4 per bushel.

South American soybean crops look to benefit from rains forecast across Argentina and Brazil in the coming six to 10 days.

"If you’re putting some subsoil moisture down in Brazil," said Kristi Van Ahn-Kjeseth, chief operating officer of consulting firm Van Ahn and Company, Inc. "That’s going to do wonders for them on their bean crop."

Technical resistance for the most-active soybean contract at the 20- and 50-day moving averages also added pressure.

U.S. soybean export sales for the week ended Oct. 7 were 2.88 million tonnes, primarily due to sales to China, beating trade expectations, according to the U.S. Department of Agriculture.

Corn losses were eased by a daily export sale of 130,000 tonnes to Mexico, as well as strong weekly ethanol production.

Corn markets were also underpinned by concerns of rising fertilizer prices, which will impact corn more than soybeans, as farmers consider planting decisions for the 2022 season.

"I think the inputs story is really what’s keeping support under the corn market," said Andrew Jackson, broker at Producers Hedge, LLC. "There are growers seriously considering going heavier beans next year."

U.S. weekly corn exports of 1.27 million tonnes were up 67% from the previous four-week session, the USDA said, near the high end of analyst expectations.

Wheat eased, pressured by a firmer U.S. dollar.

U.S. weekly wheat exports of 362,400 tonnes were down 36% from the previous week, but in line with analyst expectations. (Reporting by Christopher Walljasper; additional reporting by Naveen Thukral and Sybille de la Hamaide; Editing by Chris Reese and Paul Simao)