COMMODITIES-Oil, copper rise; gold, crops fall in choppy trade

* Commods tumble, then rebound as dollar wavers

* Oil, copper up; gold and agricultural markets end lower

* Sugar finishes at lowest level since July

* Coming up: U.S. existing homes sales data, due Tuesday

By Barani Krishnan

NEW YORK, March 22 (Reuters) - A surging dollar drove commodity prices sharply lower early before the U.S. currency slipped and many markets recovered from session lows, although sugar ended at an eight-month bottom.

Oil and copper closed up while gold and agricultural markets settled broadly lower.

The Reuters-Jefferies CRB index, which tracks prices across 19 mostly-U.S. traded commodities, fell almost 1.4 percent to a 5-1/2 week low before recovering to settle about 0.1 percent down.

The dollar initially jumped, taking commodities lower, as the euro fell on worries whether Greece will get help from its neighbors to resolve its debt crisis, or if the country must turn to the International Monetary Fund for help.

A strong dollar means higher costs for investors using the euro and other money to buy oil, gold, copper, grains and other raw materials priced in the U.S. currency. ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

Dollar vs commodities: http://link.reuters.com/kaf43j ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

The dollar fell in later trading and the euro rose, reversing losses in oil and industrial metals. But sugar still lost more than 4 percent to close at eight-month lows.

"It's exogenous factors which are really the pivots at the moment for the commodities -- it's not really internal fundamentals, it's the external elements," said Nick Moore, global head of commodity strategy at U.K.-based RBS Global Banking & Markets.

U.S. crude oil's April contract, which expired as the market's benchmark, finished up 57 cents at $81.25 a barrel. It fell to $78.57 earlier in the session.

Aside from the dollar's drop in later trading, oil was helped by higher share prices on Wall Street.

Until Friday, oil had fallen for two consecutive weeks. But traders said the market they did not think the market out of the woods yet due to signs of ample supply in crude.

"Oil fundamentals really have not improved, " said Tim Evans, energy analyst at Citi Futures Perspective in New York.

A preliminary Reuters poll showed analysts expecting data to show U.S. crude oil stocks rose 1.3 million barrels last week after crude imports increased. Official supply and demand figures will be released Wednesday by the U.S. Energy Information Administration.

Americans drove 1.6 percent fewer vehicle miles in January than in the same month of 2009, according to U.S. Department of Transportation data released on Monday. It was the first monthly decline in miles driven in a year.

Traders said existing U.S. home sales data on Tuesday will give investors in oil and other commodities a clearer picture of the economy -- and demand for raw materials.

U.S. copper for May ended up 0.80 cent at $3.3805 a lb.

But gold for April closed down $8.10 at $1,099.50 an ounce, breaking below key support at $1,100 an ounce as risk appetite improved, denting safe-haven demand.

U.S. sugar tumbled to its lowest levels in eight months, as funds sold more sugar into a market already reeling from huge losses over the past few weeks.

New York-traded raw sugar for May finished down 0.80 cent, or 4.5 percent, at 17.84 cents per lb, the weakest settlement for the spot contract since July 2009.

Raw sugar has lost 42 percent since hitting a 29-year top of 30.40 cents on Feb. 1.

"There's a lot of funds bailing out and that's why sugar broke through that old support and drove that market a little too far down, kind of like a rubber band," said Jimmy Tintle, analyst with Transworld Futures in Tampa, Florida. (Editing by David Gregorio)