Several fundamental factors have contributed to the decline in soybean prices, including early reports of better-than-expected yields of the current U.S. crop, according to University of Illinois agricultural economist Darrel Good.

Good reported that November 2012 soybean futures reached a high of $17.89 on Sept. 4, but have declined sharply since then.

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The USDA’s Sept. 12, Crop Production report containing a smaller yield and production forecast provided some brief support, but that contract has traded under $16 and is currently about $1.90 below the high.

Basis levels have also weakened over the past three weeks. “The average cash bid in central Illinois, for example, was $0.03 over November futures on Sept. 4 and $0.13 under on Sept. 21,” Good said.

The National Oilseed Processors Association report of the size of the domestic crush by its members in July was a bit smaller than expected. The July crush was 5 percent larger than that of the previous July, following year-over-year increases of nearly 14 percent in the previous three months.

The total crush for the 2011-12 marketing year may have been about 5 million bushels below the USDA forecast of 1.705 billion bushels.

Reports of an economic slowdown in China have also weighed on soybean prices.

“China is the largest consumer and importer of soybeans, accounting for 28 percent of world consumption and 64 percent of world trade in the 2011-12 marketing year,” Good said.

“An economic slowdown there raises concerns about the strength of commodity demand, including soybeans, during the year ahead. In addition, the expectation of a large South American soybean crop in 2013 provides a threat to the demand for U.S. soybeans in the last half of the 2012-13 marketing year,” he said.

Following the drought-reduced crop of 2012, the USDA projects an 11 percent increase in acreage and a 29 percent increase in South American soybean production in 2013.

Good said one of the more negative fundamental factors has been the early reports of better-than-expected yields of the current U.S. crop.

 “The USDA’s weekly Crop Progress report showed only 10 percent of the acreage harvested as of Sept. 16, but the market seems to be spooked by reports of yields exceeding producer expectations,” Good said.