Wheat was the focus last week for commodity markets and for equities where commodity groups' shares rose sharply, but some big food groups saw their share prices come under pressure.

The soaring price of the grain took investor attention away from the usual trio of gold, oil and copper.

But on Friday, after four days of supercharged rises, wheat fell sharply, closing down the daily loss limit in Chicago, posting their biggest daily percentage loss in 14 months of more than 7%.

Investors took profits in the wake of Russia's export ban on Wednesday.

Chicago Board of Trade (CBOT) September and December wheat contracts both fell by the maximum 60c, a day after finishing at the maximum daily gain.

September fell 7.6% to $US7.2575 a bushel.

Prices on the Minneapolis and Kansas City wheat markets also plunged near the daily loss limit.

In Europe, November milling wheat fell as well, closing down 6.3% at 209.50 euros a tonne.

Even after Friday's losses, the September contract in Chicago was up 10%.

Since bottoming on June 9 at $US4.2550 a bushel, wheat futures prices have soared by just over 80% up to Friday's close.

But prices are still well down on the February 2008 record high of $US13.3450 a bushel reached when fears for supplies last sent prices skywards.

Back then those fears were real as world wheat stocks had been cut by three low harvests (especially in Australia).

But since then we have had two record crops in a row, especially in the US in 2009 and 2010, meaning that global stocks are a third higher than they were in 2008 at 187 million tonnes (US Department of Agriculture).

The Paris-based Organization for Economic Development and Cooperation (OECD) said on Friday that the current situation is not comparable to the 2007-08 crop year.

The terrible drought in Russia has slashed the harvest, and traders now predict Russia's exports will drop to just 3 million tonnes - the total shipments that had left the country before the export ban was introduced last Wednesday. That's well down on the 18 million tonnes Russia sold overseas last year.

Russia says it will keep its current grain export obligations, but only after the harvest is completed and the crop situation is more clear.

That won't be until later in the year. The export ban is in place until the end of December.

The market is waiting to hear up to date information about the size of wheat crops in Kazakhstan and the Ukraine.

Both have also been hit by the drought, and there have been suggestions both might cut exports, which would add to market pressures.

The drought could cut world wheat production by 4%, according to a report last week from a forecaster called Informa Economics Inc.

They said the Russian crop will be down 21%, and global production will fall to 651 million tonnes from 679 million last year.

The forecaster said global rice production will rise 3.4% to a record 456 million tonnes from 441.1 million tonnes last year, so there will be no repeat of the rice shortages and export bans we saw in the panic of early 2008.

And for the sugar market, there was some good weather news (for buyers, not sellers).

The Indian monsoon is ahead of average and well above last year (which was terrible) and it will lift the size of the country's sugar crop substantially.

The Indian Sugar Mills Association said the crop will be a third higher next year at 25 million tonnes from the 18.7 million tonnes produced in the current season which ends on September 30.

India's monsoon is the main source of irrigation for the country's farms and was 16% above average last week, the country's meteorological department said on Friday.

That saw New York raw sugar for October delivery close at 18.24 USc a pound down 6.8% for the week, the biggest drop since late May.

Copper prices fell for a second day in a row on Friday after the US jobs figures showed the economy was still stuck in a low growth high unemployment rut.

Comex September copper eased 1.05 USc to finish at $3.3430 a lb.

Earlier in the week, the key September contract hit a three-month peak at $3.4105.

On the London Metal Exchange (LME) three month copper lost $US30 to close at $US7, 370 a tonne. On Wednesday, it hit a three-month high of $US7, 527.

Copper was down around 1% for the week, but up around 13% since the end of June.

For the year so far copper is up 21%.

Oil prices fell Friday off the back of the poor employment data.

Nymex WTI crude ended down $US1.31 a barrel at $US80.70 a barrel.

WTI is up around 14.6% so far this year.

In London Brent North Sea crude for September delivery lost $US1.45 to $US80.72.

But gold hit a three-week high on Friday, adding 1% after the dismal US payrolls report.

Comex spot gold rose as high as $USUS1, 210.90 an ounce, its highest level since July 15, and ended at $US1, 205.10 an ounce in New York.

Comex December futures settled up $US6 at $US1, 205.30 an ounce.

Gold is up around 26% so far this year.

Gold was also boosted by a weak US dollar, which fell against the euro and approached a 15-year low against the yen.

Silver rose in line with gold to $US18.44 versus $US18.31.