Crops Tracking to Our Yield Estimates

September 14, 2012 07:08 AM

USDA’s September Crop Production Report put the national average corn yield at 122.8 bu. per acre and the crop at 10.727 billion bushels. While still higher than our estimates of 120.25 bu. per acre and 10.478 billion bu., USDA’s estimates are tracking to our yield and crop pegs.

USDA’s September corn yield estimate was down just 0.6 bu. from its August peg, but that hides some significant changes in the underlying data. For example, USDA’s August yield estimate of 123.4 bu. per acre was based on an average ear population of 27,500 to 27,600 ears per acre. Its September yield estimate is based on an average ear population of about 25,700 ears per acre. That’s roughly a 7.1% decline in ear population from the August to the September Crop Production Report.

Another significant change is USDA’s assumed average ear weight. In August, the yield was based on an average ear weight of about 0.252 pounds. In September, the yield was based on an ear weight of about 0.269 lbs., a 6.7% increase.

So the yield change from August was based on a 7.1% drop in ear populations and a 6.7% increase in average ear weight.

A detailed study of USDA ear population estimates —

Some of the most reliable data collected on Crop Tour are the ear counts in 60-feet of row. Over the years, the annual changes in Crop Tour ear counts have lined up very well with USDA’s estimates of ear populations. On this year’s Tour, we found ear populations down 14.1% from year-ago in Illinois; down 8.2% in Indiana; down 9.8% in Iowa; down 5.8% in Minnesota; down 4% in Nebraska; down 11.5% in Ohio; and down 37.6% from year-ago in South Dakota.

The Nebraska data is for “all corn.” In September 2012, irrigated ear populations were up 6.1% from September 2011. Dryland ear populations in September 2012 were down 12.3% from September 2011.

USDA showed a bigger decline in ear populations from year-ago in Illinois, but the Crop Tour ear counts are off more than indicated by USDA in the other six Tour states. And based on the stalk and shank quality we saw during Tour, we expect even lower ear populations in the October Crop Production Report. That should move USDA’s yield and crop estimate closer to our estimate in the October update.

We do not, however, expect a major slide in yields. In fact, if USDA cuts enough from the harvested acreage tally in October, the national average corn yield could increase in upcoming reports.

That does not mean the crop estimate would increase — fewer harvested acres would still point the crop closer to our estimate at 10.478 billion bushels.

Similar trends in pod-count data —

Estimating soybean yields is not easy. Even collecting the data to estimate yields isn’t easy. We calculate an estimated number of pods in 9 square feet; USDA reports soybean pod estimates in 18 sq. feet in its objective yield data. Nonetheless, we can compare pod counts by comparing year-to-year percentage changes.

In Illinois, Indiana and Iowa, USDA estimated a slightly bigger decline from year-ago than we saw on the Pro Farmer Midwest Crop Tour.

Tour data and USDA data matches in Nebraska.

Tour data for Minnesota, Ohio and South Dakota reflects a bigger year-to-year decline in pod counts than indicated by USDA.

In 2009, USDA’s pod counts increased from September to the final estimate in Illinois, Indiana, Iowa, Minnesota, Nebraska and South Dakota. (Only Ohio missed this list.) That year, the bean crop had good moisture available late in the growing season.

In 2010, add Ohio to the list — all states showed an increase in pod counts from September to the final estimate. That year, western scouts were wet every day on Tour and the entire bean crop had moisture available late in the growing season.

In 2011, pod counts increased from September to the final estimate in Indiana, Iowa, Minnesota, Nebraska and Ohio. Illinois and South Dakota saw pod counts decline from September to the final estimate.

The general overall trend is for USDA’s pod counts to increase from September to the final estimate, which the Crop Tour data already reflects for Illinois, Indiana and Iowa. Because of the advanced maturity of the bean crop this year, we expect any increases in USDA’s pod counts from September to the final estimate to be less than in a typical year when the crop has available moisture.

USDA put the national average bean yield at 35.8 bu. per acre in September, down 0.8 bu. from August. The crop estimate dropped 58 million bu., to 2.634 billion bushels. We feel USDA “showed the trend” and we’ll stick with our estimates of 34.8 bu. per acre and 2.6 billion bushels.

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