A larger percentage of the U.S. corn grain acreage was harvested in August this year than is typically the case.

The availability of large, new-crop corn supplies during the last month of the previous marketing year makes it more difficult to anticipate the magnitude of old-crop stocks on Sept. 1, according to University of Illinois agricultural economist Darrel Good.

Good quoted the USDA’s weekly Crop Progress report saying that 6 percent of the corn acreage in the 18 major producing states was harvested as of Aug. 26 and 10 percent was harvested as of Sept. 2, implying about 9 percent of the acreage was harvested by the end of August.

Harvest progress by the end of August last year, and the average for the previous 5 years, was about 2.5 percent, Good said.

“If the average yield of the harvested acreage this year was near the average of 122.8 bushels forecast for the U.S, then about 965 million bushels were likely harvested in August compared to about 310 million bushels likely harvested in August last year,” Good said.

“However, this year the most advanced harvest progress, relative to average and to that of last year, was in Kansas, Kentucky, Missouri, and Tennessee where state average yields are projected to range from 70 to 91 bushels, or 36 to 53 bushels below the national average yield.”

Harvest progress in southern states not included in the 18-state report was well advanced by the end of August, but with progress well ahead of last year’s pace only in Arkansas and to a lesser extent in Louisiana.  

Progress was behind that of last year in the other southern states. “It seems likely that new-crop corn available before Sept. 1 this year was about 600 million bushels larger than the availability of a year ago,” Good said.

The question is how much of the newly harvested crop was actually consumed in August.

Good said that the degree of substitution of new-crop for old-crop corn in August has implications for the magnitude of old-crop corn still in inventory on Sept. 1.

He explained that regardless of how new-crop corn was consumed in August (feed, export, or domestic processing) it will be reflected in the balance sheet in the feed and residual category.  

The USDA has forecast the Sept. 1 inventory of old-crop corn at 1.181 billion bushels, implying consumption of old-crop corn during the fourth quarter of the 2011-12 marketing year of 1.974 billion bushels.