Corn Yield Forecasts as of Sept. 7

Corn Yield Forecasts as of Sept. 7

To evaluate, in “real-time,” the impact of this season’s weather on corn yield and its spatial variability across the Corn Belt, simulations of 2016 end-of-season corn yield potential and real-time crop stage are performed for 41 locations. The simulations were developed using the UNL Hybrid-Maize model in collaboration with faculty and extension educators from 10 universities.

This is the fifth article in a series that summarizes the simulated crop stages and yield forecasts across the Corn Belt. Data for the Sept. 7 forecasts for actual and potential yields, as well predicted dates for physiological maturity (“black layer”), can be downloaded here. Previous corn yield forecasts for this year can be found here. Details on Hybrid-Maize and underpinning methodology to forecast end-of-season yields, as well as on interpretation and uses of yield forecasts, are described in a previous article.

During the last two weeks there were below-average (nighttime and daytime) temperatures in Illinois, Indiana, Michigan, and Ohio, near-average temperatures in Iowa, and below-average daytime temperatures in Nebraska. Rainy and cloudy conditions prevailed in Nebraska during this period. The rest of the locations exhibited near- or above-average rainfall, except for a few sites in Illinois and Iowa. Weather conditions during the last two weeks are shown in Figure 1.

Going to Husker Harvst Days?

Be sure to stop by the IANR Building to visit with researchers developing these corn yield models and see their exhibit. Read more.

Chart showing factors affecting crop growth at each site

Figure 1. Daily solar radiation, maximum and minimum air temperature (Tmax and Tmin), total rainfall, and total reference grass-based evapotranspiration (ET) for the time from August 25 to September 7, 2016. Vertical bars indicate the range for these variables based on 20+ years of weather records. The horizontal thick line indicates the long-term average and the red dots indicate the 2016 values.

Simulated Corn Stage Across 41 Locations

Physiological maturity (black layer) has been reached at about half of the rainfed sites (Figure 2). These sites are in the southern Corn Belt. Grain filling continues in the other half of rainfed sites, with most corn at dent stage. Irrigated corn has matured (Kansas) or will reach maturity soon (Nebraska).

Simulated irrigated corn stages by Aug. 24

Figure 2. Simulated crop developmental stage for irrigated and rainfed corn at each location. R4: dough; R5: dent; matured (“black layer”).

Simulated rainfed corn stage by Aug. 24

Irrigated Corn: Slightly Above-Average Yields

The range of forecasted irrigated corn yields for each location, as well as the probabilities for yields above, near, or below average, are shown in Figures 3 and 4. The irrigated sites where corn has already matured exhibit yields slightly above average (+6%), except for Beatrice. A similar scenario is forecasted for the rest of the irrigated sites where maturity has not been reached yet.

Map indicating probability of yield deviation for irrigated corn July 13

Figure 4. Probability of obtaining a 2016 yield below (≤10%, red color), near (±10%, yellow color), and above (>10%, green color) the long-term (2005-2014) average at each location. The larger a color section is within the pie chart, the higher the probability that corn yield will be in that category.

Probability of yield deviations for rainfed corn

Rainfed Corn: High Yield Variation Across Sites

Forecasted yields for rainfed corn indicate near-average yield at about half of 37 rainfed sites (Figures 3 and 4). These sites are mainly in the southern and eastern Corn Belt. Above-average yields are expected for 11 of the rainfed locations: western and central Nebraska (North Platte, Holdrege, and McCook), central-east and northeastern Nebraska, southwestern Iowa, and northwestern Missouri (Mead, Concord, Lewis, and St Joseph), eastern North Dakota and western Minnesota (Dazey, Eldred, and Lamberton), and central Illinois (Peoria). In contrast, the forecasts indicate below-average yield at five sites: southeastern Nebraska (Clay Center and Beatrice), and across a southeast-northwest transect in Iowa (Crawfordsville, Ames, and Sutherland).

State-Level Forecasted Corn Yields

Our yield forecasts were upscaled to state level using the spatial framework of the Global Yield Gap Atlas, which is based on agro-climatic zones and distribution of corn harvested area. Forecasted yields for 2016, for each state and water regime, are shown below. For comparison, we also show the average corn yield reported by USDA-NASS for the last 10 years.

Forecasted 2016 state average yields in comparison to long-term average yields fall

  • well above average (10% or more) in Nebraska (rainfed) and Minnesota (rainfed),
  • slightly above average (3-9%) in Indiana, Illinois (both rainfed), and Kansas (rainfed and irrigated) ,
  • near-average in Nebraska (irrigated) and Missouri and Ohio (both rainfed), and
  • below-average (6%) in Iowa (rainfed).
Table 1. Forecasted corn yields for 2016 and the average corn yield reported by USDA-NASS for the last 10 years for each state and water regime.
State*Water regime

Forecasted 2016 yield

Average (2006-2015) yield

% deviation‡Previous record yield
Nebraska Irrigated 193 191 +1 207
Rainfed 139 126 +10 154
Kansas Irrigated 202 186 +9 206
Rainfed 99 93 +6 123
Iowa Rainfed 160 170 -6 192
Minnesota Rainfed 197 164 +20 188
Missouri Rainfed 137 135 +1 186
Illionois Rainfed 175 166 +5 200
Indiana Rainfed 160 156 +3 188
* North Dakota and Michigan were not included because we only forecasted yield for one site at each of these states. Note that uncertainty in Minnesota statewide yield is also higher due to the small number of sites for which corn yields were forecasted.
** Based on our median 2016 forecasted actual yield estimated for each location.
† State 10-year (2006-2015) average yield reported by USDA-NASS.
‡ Deviation of forecasted 2016 yield relative to average (2006-2015) yield.
¶ Highest statewide average yield reported by USDA NASS during the last 10 (2006-2015) years.


Overall, our Sept. 7 forecasts suggest a near or slightly above average yield for the entire Corn Belt, with no clear indication of a record yield crop in 2016. Our forecasts indicate a high probability of near-average corn yields in 2016 in about half of rainfed sites, with above- and below-average yields expected in the rest of the locations. Slightly above-average yields are likely for irrigated corn.

Note that these forecasts do not take into consideration problems with stand emergence, hail/flooding damage, replanting situations, disease, or nitrate leaching. In fields negatively affected by these constraints, actual yields will be lower than estimates provided here. It is important to keep in mind that yield forecasts are not field specific and, instead, represent an estimate of average on-farm yield for a given location and surrounding area in absence of the yield-reducing factors mentioned here. Likewise, crop development stages and forecasted yields will deviate from the ones reported here in fields with planting dates or hybrid maturities that differ markedly from the ones used as the basis for these forecasts.

Watch for a final end-of-season report in late September.

For more information contact Patricio Grassini at or 402-472-5554.

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