August 17, 2017 / 7:21 PM / 10 months ago

Illinois crops need rain to hit yield forecasts: Braun

CHICAGO (Reuters) - Illinois corn and soybean yields may be in danger of falling short of forecasts, as significant contributions from the weather are still needed in the eastern half of the state.

FILE PHOTO: Rows of corn wait to be harvested in a field in Minooka, Illinois, September 24, 2014. REUTERS/Jim Young/File Photo

This year, the U.S. Department of Agriculture does not expect Illinois to set new yield records. Last week, the agency pegged the state’s corn and soybean yields at 188 and 58 bushels per acre, respectively.

For corn, this falls below both the 197 bpa in 2016 and the record 200 bpa set in 2014. For soybeans, the forecast is just shy of 2016’s record of 59 bpa. Illinois is the leading soybean state and is second to Iowa in corn.

Based on a crop tour conducted this week in Illinois agricultural districts 50 and 70, district 50 – in the east-central part of the state – might weigh down the state average corn yield just a touch based on irreversible impacts from heat and dryness this summer. The outcome for soybeans could still be very good here, but that all rides on rainfall within the next two weeks.

District 70 – in east-southeast Illinois – has been luckier with the rain lately, but several dry spots still exist, leading to a large amount of variability. The field surveys indicate that this district is pulling its weight in soybeans, and it may be able to perform near last year’s levels in corn with a little help from weather.

In 2016, IL70 was the top soybean-producing district in the country while IL50 came in fifth. Together, these districts made up roughly 4 percent of both the nation’s soybean and corn harvests last year.


This summer has featured highly variable weather across the state of Illinois. The northern third of the state was extremely wet in July, while rain has been hit-or-miss in the bottom two-thirds for the past two months. And although August has been favorably cool so far, periods of heat in June and July hurt some corn fields.

From Chicago into the northern portion of IL50, impacts of the earlier excessive moisture were visible. This was especially the case for soybeans, which displayed a lot of drowned-out spots, weeds, and uneven plant heights. Bean yield potential was the lowest of the trip in this area (

Fields just east of Champaign in IL50 were the driest of the entire route. The moisture stress was especially visible in corn, as many plants had begun to die and turn brown – much earlier than they should (

The soybeans in this dry pocket actually looked pretty good, but they will not be able to put on more pods and make bigger beans without rainfall in the next week or two. Little pods and flowers at the top of the plant show the potential for heavy podding there – which is key for driving big yields – but this cannot happen without moisture.

Of the whole trip, soybeans looked the best in eastern IL70, the area that was sampled. Fields were uniform and largely weed-free, plants were thick and bushy, and just as in IL50, plants could still put on some more pods especially near the top with some timely rains (

Heavy rains in April and early May led to a lot of replanting of corn in IL70, which was apparent this week by the variety of stages the crops had reached. There was no clear advantage of the earlier-planted fields versus later or replants, most likely due to the high regional variability of the weather this summer (

Due to heat stress earlier in the summer, corn tip-back – when the kernels do not fill out the full length of the ear – was present in both districts although it was not necessarily the case in every field. This was most prominent in the northernmost and southernmost fields that were sampled.


A total of 31 fields were sampled using the same methodology as the widely followed Farm Journal Midwest Crop Tour, which will kick off its 2017 run on Monday. The data collected this week in Illinois is compared with what scouts found on the 2016 FJ Tour.

A rough corn yield is computed using the ear count, length of grain on ears, kernel circumference on ears, and row spacing. For soybeans, pods and plants are counted to derive the number of pods in a three-by-three-foot area.

In IL50, the average corn yield was 190.3 bpa over eight samples. Last year, FJ Tour scouts pulled 45 samples that averaged 194.04 bpa. The key difference in the numbers was a lower ear count in 2017.

Six soybean samples in IL50 resulted in a pod count of 1,250, lower than the 1,499 pods that FJ Tour computed in 2016 using 45 data points.

In IL70, eight corn samples had an average yield of 176.6 bpa, very close to the 173.7 bpa that FJ Tour derived in 2016 using 11 samples. More ears and more kernel rows gave the 2017 calculation an edge.

Soybeans in IL70 also outperformed last year’s FJ Tour results. Eight samples averaged 1,304 pods, well above the 1,109 pods computed over 11 samples in 2016.

(The opinions expressed here are those of the author, a market analyst for Reuters.)

Editing by Matthew Lewis

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