Crop Stages and Weather Conditions During the Last Four Weeks
Corn has reached black layer at all irrigated sites and at most of rainfed locations of the Corn Belt, except for those situated along the north and eastern fringes of the region (Figure 2).
During the last four weeks, most sites across the Corn Belt exhibited near-normal temperature, although above-normal daily temperatures were registered in the western (NE and KS) and northern (ND) states.
While sites in the eastern fringe of the Corn Belt (OH, IN, IL) exhibited near-normal rainfall, the majority of locations had below-normal rainfall. A summary of weather conditions during the past three weeks is shown in Figure 1.
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 period between Aug. 16 and Sept. 13, 2022. Vertical bars indicate the range for these variables based on 20-plus years of weather records. The horizontal thick line indicates the long-term average and the red dots indicate the 2022 values. Click Image to Enlarge
Figure 2a. Simulated developmental stage for irrigated corn at each location. R4: dough; R5: dent; physiological maturity: matured. Click Image to Enlarge
Figure 2b. Simulated developmental stage for rainfed corn at each location. R4: dough; R5: dent; physiological maturity: matured. Click Image to Enlarge
Near but Below Average Yields in Irrigated Corn
Forecasted end-of-season irrigated yields are shown in Figure 3 and 4. Four sites (out of 13) exhibited below-average yields (that is with a difference >10%). Compared with our previous forecast, above-average temperature during the past four weeks in NE further reduced the forecasted yield for 2022. Expected yields in NE are consistently lower than historical average, with an average difference of 10%. Overall, the irrigated maize yield potential forecasted for the current 2022 season is 5% lower, on average, compared to that in the previous (2021) season.
Rainfed Corn: Yield Potential is Highly Variable Across Rainfed Sites
Forecasted end-of-season yields for rainfed corn indicate above-average yields at only 22% (eight out of 36) of the sites, and these were distributed in the southern fringe of the region (eastern KS and MO), western IL, southern OH and southeastern MN (Figure 3 and 4).
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In contrast, 42% of the sites (15 out of 36) exhibited below-average yields. These sites with below-average yield were located in NE, ND, most of IA, central KS and northern MN.
The remaining 13 sites, mostly located in the eastern part of the Corn Belt (eastern IL, IN and OH), showed a high probability of near-average yield.
Overall, this year’s scenario looks similar to last year’s forecast but 9% lower than the long-term average. Compared to the 2021 season, one-third of the rainfed sites exhibited a decrease in yield potential that was larger than 5%, especially at sites in NE, IA and KS. Another one-third of the sites improved yields by at least 5%, compared with the 2021 season, especially in MO, OH, IN, MN and ND.
Figure 3a. Vertical lines indicate the range of forecasted 2022 irrigated corn yield potential by Sept. 14 based on average 2022 planting date at each location. Horizontal lines indicate the 25th and 75th percentiles of the yield distribution (associated with respective adverse and favorable weather scenarios during the rest of the season). The blue squares indicate the long-term average yield potential at each location and the red dots represent the forecasted 2022 corn yield potential at sites that have already reached maturity. Click Image to Enlarge
Figure 3b. Vertical lines indicate the range of forecasted 2022 rainfed corn yield potential by Sept. 14 based on average 2022 planting date at each location. Horizontal lines indicate the 25th and 75th percentiles of the yield distribution (associated with respective adverse and favorable weather scenarios during the rest of the season). The blue squares indicate the long-term average yield potential at each location and the red dots represent the forecasted 2022 corn yield potential at sites that have already reached maturity. Click Image to Enlarge
Figure 4a. Probability of the 2022 irrigated yield potential to be below (<10%, red color), near (± 10%, yellow color), and above (>10%, green color) the long-term average yield potential at each location. The larger a color section is within the pie chart, the higher the probability that end-of-season corn yield will be in that category. Click Image to Enlarge
Figure 4b. Probability of the 2022 rainfed yield potential to be below (<10%, red color), near (± 10%, yellow color), and above (>10%, green color) the long-term average yield potential at each location. The larger a color section is within the pie chart, the higher the probability that end-of-season corn yield will be in that category. Click Image to Enlarge
Conclusions
Our forecasted yield potential this season seems to be almost 10% below the historical average for both rainfed and irrigated corn overall. The USDA also forecasts that 2022 corn yield will be lower than that predicted from the long-term historical trend.
Our forecast suggests a near but below-average year for most irrigated sites, although one-third of them can expect yields to be well below (>10%) the historical average.
For rainfed corn, the scenario is diverse across regions. Most sites in the eastern part of the Corn Belt have a high probability of near-average yields. Above-average yield is expected at eight locations in eastern KS, MO, western IL, southern OH and southeastern MN. In contrast, 13 sites located in northern and western fringes of the Corn Belt and IA exhibit a high probability of below-average yields.
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 stages and forecasted yields will deviate from those reported here in fields with planting dates or hybrid maturities that differ markedly from those used as the basis for these forecasts.
