CANBERRA, March 19 (Reuters) - Chicago wheat futures edged lower on Tuesday, with ample supply holding prices near their lowest since 2020 despite Russian attacks on Ukrainian port infrastructure that threatened exports and pushed prices up more than 2% on Monday.

Soybeans fell slightly, while corn edged higher.

FUNDAMENTALS

* The most-active wheat contract on the Chicago Board of Trade (CBOT) was down 0.1% at $5.42 a bushel, as of 0005 GMT. Prices fell to $5.23-1/2, the lowest since August 2020, on March 11.

* CBOT soybeans slipped 0.1% to $11.87 a bushel and corn was up 0.1% at $4.36-1/4 a bushel. Prices of both grains have risen in recent weeks but remain close to their lowest since 2020.

* Russian air attacks at the weekend damaged agricultural enterprises and destroyed several industrial buildings in the Black Sea port of Odesa.

* The Black Sea port city of Mykolaiv was also hit, with Ukrainian strikes against Russian oil refineries and Vladimir Putin's re-election as Russia's president raising fears that tensions might escalate.

* Speculators hold large short positions in Chicago wheat, as well as in corn and soybeans, making them vulnerable to bursts of short covering that can cause rapid price gains.

* Commodity funds were net buyers of CBOT wheat and net sellers of soybeans and corn on Monday, traders said.

* Top wheat exporter Russia has flooded the market with cheap supply after two large production years, and a third bumper harvest is expected there this year.

* Russian wheat export prices rose last week for the first time since early January, analysts said.

* Elsewhere, Ukraine's 2024 corn sowing area is likely to decrease by 4.5% from last year to 3.863 million hectares, the agriculture ministry said, with farmers also set to decrease the sown area of spring wheat and sunflower and increase the sown area of spring barley and soybeans.

* Brazil's 2023/24 soybean harvest had reached 63% of the planted area as of last Thursday, up 8% from a week earlier, consultants AgRural said on Monday, adding that planting of Brazil's second corn crop was 97% complete.

* Drought in the western Canadian province of Alberta is stretching into its fourth year and farmers are planning for water restrictions that threaten production of wheat and beef.

MARKETS NEWS

* Global stocks rose on Monday while Treasury yields crept higher ahead of this week's raft of central bank meetings that could end sub-zero interest rates in Japan and set a blueprint for U.S. rate cuts this year.

(Reporting by Peter Hobson; Editing by Subhranshu Sahu)