By The Associated PressCorn is ending the week higher as dry weather in Argentina threatens to damage crops. The grain has climbed 2.2 percent this week and advanced in three out of the last four weeks, since falling to a six-month low of $6.80 a bushel Jan. 4. The grain fell back 4.5 cents to close at $7.36 a bushel Friday, after climbing as high as $7.46 during trading. A spell of dry weather in South America may harm corn during its crucial pollination phase, said Sterling Smith, a commodities analyst at Citigroup. Corn surged last summer after a drought in the U.S. plains region decimated the harvest. "We saw some good pre-pollination rains," said Smith. "If we don't see the rain afterward, we could see some crop problems." In other grain trading, wheat fell 14.50 cents to $7.65 a bushel and soybeans rose 5.75 cents a bushel to $14.7425. Metals advanced, with silver leading the gains, after a government report showed that hiring rose in January and was stronger at the end of 2012 than previously thought. Silver for March delivery rose 60.7 cents to $31.9580 an ounce. Gold for April delivery gained $8.60 an ounce to $1,670.60. Copper, which has a range of industrial uses and tracks the outlook for global demand, rose. The March contract for the metal rose 5.25 cents to $3.7845 a pound. Platinum for April delivery rose $12.30 to $1,687.70 an ounce. March palladium gained $10.70 to $756.40. The employment report also helped push oil prices higher, with data showing that U.S. manufacturing activity accelerated in January, also lifting demand. Benchmark oil for March delivery rose 28 cents to $97.77. Natural gas for March delivery fell 3.8 cents to end at $3.30 per 1,000 cubic feet. March heating oil rose 4.2 cents, to finish at $3.16 a gallon, and wholesale gasoline for March delivery rose 2.2 cents to end the day at $3.05 a gallon.