CHICAGO, July 14 (Xinhua) -- Chicago Board of Trade (CBOT) agricultural commodities closed sharply lower over the trading week which ended July 13, with soybean futures plunging over 6 percent as investors turned to technical selling amid renewed China-U.S. trade frictions.

The most active corn contract for December delivery fell 18.25 cents weekly, or 4.89 percent, to 3.5475 dollars per bushel. September wheat delivery went down 18.25 cents, or 3.54 percent, to 4.97 dollars per bushel. November soybeans dropped 60.25 cents, or 6.74 percent, to 8.3425 dollars per bushel over the week.

Corn fell over 18 cents through the week with fund selling largely tied to weakness in the soybean complex. July expired at the end of Friday's trade at 3.30 dollars per bushel to mark the lowest weekly close since late 2016.

However, while price has declined, the U.S. and world corn balance sheets have steadily tightened on strong demand and falling crops. Record large hog and cattle herds ensure strong domestic feed demand, while the U.S. ethanol industry is realizing healthy margins of close to 15 cents per gallon.

U.S. wheat futures fell to sharp losses following the decline in soybean futures related to reduced U.S. demand from China and growing U.S. stocks.

However, world wheat production of the world's major exporters has declined nearly 30 million tonnes from last year and Black Sea prices are starting to take notice. The U.S. Department of Agriculture(USDA) estimated the 2018 Russian wheat crop at 67 million tonnes vs. 85 million tonnes last year.

Russian agriculture minister even reduced their crop estimate on Friday to 64.4 million tonnes. Analysts hold that based on early harvested yield data, that the crop could decline as far as 61.5 million tonnes. And there is still the risk for spring wheat yield should the 2018 growing season end on a timely basis.

The point is that U.S. wheat export demand could surge once Black Sea and EU wheat stocks are exhausted amid a declining Australian crop.

Selling in the soybean markets continued through last week taking spot futures to the lowest level since 2008. U.S. crush and export demand continues at an unprecedented rate, but the the world's largest soybean buyer out of the U.S. market, U.S. and world end users are content living on a needed basis.

The USDA weighed in with their best estimates for U.S. and world soybean trade for the year ahead, and cut the forecast for U.S. exports. That change was largely anticipated.

Even with reduced Chinese trade, analysts see the soybean market as undervalued. A resolution to trade or a plan from the USDA for price support would send CBOT futures sharply higher.