* Oil, iron ore headed for biggest weekly fall since Nov
* Copper, corn looking at weakest week since Aug
* Coming up: U.S. nonfarm payrolls at 1330 GMT
By Manolo Serapio Jr
MANILA, March 10 (Reuters) - Global commodities from oil to metals and grains were on course to post their steepest weekly declines in months on Friday as the recent rallies in the asset class showed signs of fatigue, pressured by a glut and tepid demand from top consumer China.
Gold, which investors typically run to when they flee risky assets, was not spared from this week's selloff as the metal dropped below the critical $1,200 an ounce support amid a looming U.S. interest rate hike.
The Thomson Reuters CRB index, a measure of 19 commodities, is headed for its biggest weekly fall since November.
China's decision on Sunday to cut its economic growth target this year to around 6.5 percent "came across as slightly negative for commodities," said Vishnu Varathan, senior economist at Mizuho Bank.
"But the underlying tone there is there should be some support on the way down because China hasn't really relinquished its desire for growth stability either," said Varathan.
"Commodities might take a step back, a bit of a breather from the rally last year, but the hopes are tilted to the upside."
With little pull from China, the market focus shifted back to the surplus of raw materials, dragging down commodities after last year's recovery.
U.S. crude oil, which fell below $50 a barrel on Thursday for the first time since mid-December, has lost nearly 7 percent so far this week, the most since November. It was up 0.8 percent at $49.68 by 0916 GMT.
Brent crude, last up 0.7 percent at $52.55 a barrel, has fallen 6 percent for the week, also the biggest since November.
"Steep price falls in the last two days amid building U.S. inventories show that the market remains concerned about the supply-demand balance," NAB Group Economics said in a note.
Three-month copper on the London Metal Exchange, trading near a two-month low at $5,707 a tonne, has declined 3.5 percent this week, heading for its largest such drop since August.
Stocks at LME warehouses have risen to the highest since December amid worries over Asian demand. MCUSTX-TOTAL
Iron ore, at a one-month trough below $87 a tonne .IO62-CNO=MB, was headed for its worst week since mid-November, amid a growing mountain of stocks at Chinese ports - the highest since at least 2004 at around 130 million tonnes. SH-TOT-IRONINV
Iron ore rallied with steel this year despite rising port stocks. But as steel prices pulled back, concerns emerged over the expanding inventory of the steelmaking ingredient that could increase further.
In agriculture, Chicago soybean futures were poised for their biggest weekly loss since December on forecasts for a record Brazilian crop and corn was eyeing its biggest weekly decline since August.
A stronger dollar pulled down spot gold to its weakest since Jan. 31 ahead of key U.S. jobs data that may reinforce expectations for a rate increase next week when Federal Reserve policymakers meet.
The precious metal has dropped 3 percent this week, the most since November.
"Gold will be under pressure going into the FOMC meeting and hover around the $1,185-$1,190 level," said Ronald Leung, chief dealer at Lee Cheong Gold Dealers in Hong Kong.
Reporting by Manolo Serapio Jr.; Editing by Christian Schmollinger