Corn came under additional pressure from forecasts of improved weather in the US Midwest, which raised expectations of progress in this year's delayed plantings.
Al Qaeda's elusive leader Osama bin Laden was killed in a mansion outside the Pakistani capital Islamabad, US President Barack Obama announced.
‘It is all about erosion of risk premium. If Osama is taken out, you are going to see risk premium being wiped out from the market,’ said Jonathan Barratt, managing director at Commodity Broking Services in Sydney.
Analysts say the drop in risk premium on commodities could be short-lived. Chicago Board of Trade front-month May corn fell 1.03 percent to $7.46-1/4 a bushel by 1130 GMT and wheat shed 1.01 percent to 7.61-1/2 a bushel.
More actively traded July corn fell 0.76 percent to $7.50-3/4 a bushel while July wheat added 0.19 percent to $8.02-3/4 a bushel.
July soybeans lost 0.39 percent to $13.88-1/2 a bushel.
Uncertainy remains over crop weather and is adding to volatility in the corn, wheat and soybean markets.
More planters will roll across the soaked US Midwest grain belt this week, but there is a lot of catching up to do in seeding this year's corn crop.
‘Better weather is forecast for the United States. It seems to be warming and drying, so that's a nice change,’ said Adam Davis, a senior commodity analyst at Merricks Capital, a Melbourne-based funds manager which invests in agriculture.
‘The market should come down from here because we were strong up on Friday and running into the weekend, with the weather improving for corn.’
Excessively wet weather in the United States has slowed corn plantings, leading to concerns about a late start for this year's crop and a potential for reduced production.
USDA REPORT
Analysts expect a government report later on Monday to show US corn plantings at only 15 to 19 percent complete, versus an average of about 40 percent for this time of year.
Investors see any decline in corn prices as an opportunity to snap up cheap supplies in view of outlooks for the US corn stockpile to fall to the lowest since the 1930s this year.
There were no deliveries on the May futures contracts for corn and soybeans and only light deliveries for wheat. Light deliveries on a futures contract indicate that owners of the commodity want to keep it, a bullish signal for futures prices.
Hedge funds and other speculators boosted their net long position in Chicago Board of Trade soybean futures by 27 percent as prices rallied 3 percent, according to government data issued on Friday.
‘This high interest of financial investors could lead to selling pressure if profit-taking takes place, for example if the weather conditions and therefore planting conditions improve,’ Germany's Commerzbank said in a research note.
Benchmark European milling wheat firmed slightly on lingering concerns over drought in major exporters France and Germany, with the November contract up 0.12 percent at 216.00 euros/tonne on the Euronext exchange in Paris.
‘It's not a few showers or storms that are going to change things,’ Michel Portier, head of French grains consultancy Agritel, said. ‘Fundamentals remain bullish because of the weather conditions.’