Chicago Board of Trade (CBOT) grains futures closed mixed over the trade week which ended Aug. 25, as fund selling and the professional crop tour weighed on grains prices.

The most active corn contract for December delivery dropped 12.25 cents weekly, or 3.35 percent, to 3.535 dollars per bushel. September wheat delivery fell 7.25 cents weekly, or 1.64 percent, to 4.3525 dollars per bushel. November soybeans rose 6.75 cents weekly, or 0.72 percent, to 9.445 dollars per bushel.

Corn futures set new contract low, mostly amid a lack of fresh demand news and unexciting reports from Farm Journal's Crop Tour implemented this week.

Analysts maintain that the most probable U.S. corn yield lies within a range of 165-166 bushels per acre, which still will strip 300-400 million bushels of supply from the U.S. balance sheet.

U.S. export demand will be lacking in 2017, but there are signs of growth in bio-fuel demand. And amid a collapse in Brazilian cash prices, traders doubt acreage expansion there will be very robust in 2018.

Wheat futures also fell to new contract lows as Russia's wheat crop estimate continued to get bigger, and the trade fiercely debates Russia's ability to export more than 29-31 million tons. Part of this will hinge upon the severity of winter weather, but analysts suggest that without abandoning corn and barley exports altogether, Russia's export capacity is indeed roughly 30-31 million tonnes.

Russian production, which will stay robust for years to come, will simply spill into end stocks without massive investment in infrastructure. The market has digested the boost in major exporter stocks and use. Moving forward, a supportive outlook is advised and a demand-led recovery is anticipated this autumn.

Amid current world fob spreads, the U.S. market is well positioned to exceed the United States Department of Agriculture (USDA)'s export forecast by 75-100 million bushels.

This along with a fall of another 20-40 million bushels of U.S. spring wheat due to a 1-1.4 million acre rise in abandonment would drop U.S. 2017/18 wheat stocks closer to 800-850 million bushels. The sharp fall in the U.S. dollar will reduce seeding globally and the market is starting to more closely focus on Australian weather.

It was a firm, but quieter week of trade in the soybean market that left prices moderately higher at Friday's close. Strong new crop sales, along with the U.S. Commerce Department's ruling against Argentine and Indonesian biodiesel imports were supportive.

And the Farm Journal Crop Tour that had the market's attention. Based on crop samples collected across the corn belt states, the tour estimated a national soybean yield of 48.5 bushels per acre, down 0.9 bushel from the USDA's August forecast. On average, the Tour's yield projection has been within 0.6 bushel per acre of USDA's September crop report.

Analysts note that collective pod counts were the lowest since 2013 and that to achieve a 48.5 bushels per acre yield requires another year of high pod weights, which is doubtful. Moreover, August will be the 7th or 8th coolest since 1895, which is likely to harm the soyoil yield, further tightening U.S. soyoil supplies.