2020 Corn Yield Forecasts as of July 14

2020 Corn Yield Forecasts as of July 14

Patricio Grassini, UNL Associate Professor of Agronomy and Horticulture, Extension Cropping System Specialist and Water for Food Institute Fellow; Jose Andrade, UNL Affiliate; Juan Ignacio Rattalino Edreira, UNL Research Assistant Professor of Agronomy and Horticulture; Gonzalo Rizzo, UNL PhD student; Haishun Yang, UNL Associate Professor of Agronomy and Horticulture and Water for Food Institute Fellow; Keith Glewen & Jennifer Rees, Nebraska Extension Educators; Jeff Coulter, Professor and Extension Specialist, University of Minnesota; Mark Licht (Extension Cropping System Agronomist) & Sotirios Archontoulis (Assistant Professor), Iowa State University; Ignacio Ciampitti, Crop Production and Cropping System Specialist and Assistant Professor of Agronomy, Kansas State University; Ray Massey, Extension Professor, University of Missouri

Simulations of 2020 end-of-season corn yield potential and real-time crop stage were performed on July 14 for 40 locations across the US Corn Belt using the UNL Hybrid-Maize crop model in collaboration with faculty and extension educators from ten universities. This article summarizes the simulated crop stages and yield forecasts; the data can be found in Table 1 below. Details on the UNL Hybrid-Maize crop model and the underpinning methodology to simulate phenology and forecast end-of-season yields, as well as on interpretation and uses of yield forecasts, are described in a previous article. Note that one location in IA (Kanawha) was not included for the forecasts due to lack of weather data.

A summary of weather conditions during the last 60 days (from May 14 to July 13) is shown in Figure 1. The season started with warm conditions throughout the Corn Belt, showing average temperature above normal in most cases. In contrast, rainfall was more erratic, with most locations exhibiting near or above normal records, except for western KS and NE, eastern NE and western IA, and a few scattered locations in IL and IN with rainfall below normal.

Graph of Daily solar radiation, maximum and minimum air temperature, total rainfall, and total reference grass-based evapotranspiration (ET) for the time period between May 14 and July 13, 2020
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 May 14 and July 13, 2020. 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 2020 values for the same period.
Table 1. Data from simulations of 2020 end-of-season corn yield potential and real-time crop stage performed on July 14
Location Water regime Long-term average yield (bu/ac) § Range of Yp forecasts as of Jul 14 (bu/ac)¶ 25th Range of Yp forecasts as of Jul 14 (bu/ac)¶ 75th Below (relative to the long-term Yp)† Near (relative to the long-term Yp)† Above (relative to the long-term Yp)† Simulated current crop stage*
NE Alliance Irrigated 194 194 224 0% 65% 35% V14
Beatrice Dryland 143 81 136 63% 13% 23% R1, Silking
Irrigated 230 218 248 3% 73% 23% R1, Silking
Clay Center Dryland 153 48 121 87% 11% 3% R1, Silking
Irrigated 245 238 264 5% 74% 21% R1, Silking
Concord Dryland 172 125 203 45% 26% 29% V18
Irrigated 248 245 283 3% 61% 37% V18
Elgin Irrigated 252 241 276 3% 72% 25% V16
Holdrege Dryland 109 58 129 47% 16% 38% R1, Silking
Irrigated 242 229 264 9% 75% 16% V18
McCook Dryland 84 36 86 63% 13% 24% R1, Silking
225 211 243 13% 74% 13% V18
Mead Dryland 177 110 154 79% 16% 5% V18
Irrigated 235 222 256 8% 71% 21% R1, Silking
North Platte Dryland 86 38 93 53% 24% 24% V16
Irrigated 235 225 263 11% 58% 32% V16
O'Neill Irrigated 227 216 250 9% 63% 29% V14
IA Ames Dryland 231 204 238 28% 56% 16% R1, Silking
Crawfordsville Dryland 228 229 250 7% 70% 23% R1, Silking
Lewis Dryland 205 169 213 55% 32% 14% V18
Nashua Dryland 230 223 250 6% 74% 19% V16
Sutherland Dryland 210 189 225 23% 55% 23% V16
IL Bondville Dryland 228 211 251 18% 57% 25% V18
Freeport Dryland 209 217 256 3% 47% 50% V16
Olney Dryland 180 133 190 47% 43% 10% R1, Silking
Peoria Dryland 204 193 222 4% 78% 19% R1, Silking
Springfield Dryland 166 166 202 15% 35% 50% R1, Silking
IN Butlerville Dryland 224 202 229 24% 59% 18% V18
Columbia City Dryland 221 201 244 24% 47% 29% V16
Davis Dryland 227 226 245 0% 100% 0% V16
West Lafayette Dryland 235 230 247 6% 82% 12% V18
KS Garden City Irrigated 219 205 231 21% 68% 12% R2, Blister
Hutchinson Dryland 90 57 108 60% 7% 33% R3, Milk
Manhattan Dryland 128 114 166 26% 20% 54% R2, Blister
Scandia Dryland 122 82 150 56% 15% 29% R1, Silking
Irrigated 224 214 259 6% 59% 35% V18
Silverlake Dryland 129 126 165 15% 29% 56% R2, Blister
Irrigated 209 186 218 29% 59% 12% R2, Blister
MI Ceresco Dryland 178 191 241 11% 21% 68% V12
MN Eldred Dryland 104 128 160 0% 8% 92% V12
Lamberton Dryland 206 209 236 0% 39% 61% V16
Waseca Dryland 214 217 253 8% 52% 40% V16
MO Brunswick Dryland 178 123 188 50% 30% 20% R1, Silking
Monroe City Dryland 163 143 230 32% 16% 53% V18
St Joseph Dryland 159 145 184 25% 40% 35% R1, Silking
ND Dazey Dryland 106 68 145 52% 8% 40% V10
OH Custar Dryland 204 186 211 23% 71% 6% V16
South Charleston Dryland 207 158 209 51% 40% 9% V16
Wooster Dryland 208 192 229 14% 60% 26% V14

§Long-term (last 20+ years) potential yield at each location and surrounding area.
¶ Range of forecasted 2020 potential yields based on average planting date in 2020, indicating the potential yields in the 25th and 75th percentile of the potential yield distribution (associated with respective adverse and favorable weather scenarios during the rest of the season).
† Probability of obtaining a 2020 yield below (<-10%), near (±10%), and above (>10%) than the long-term potential yield at each location.

Simulated Corn Stage Across 40 Locations

Corn has reached silking in most of the southern fringe of the Corn Belt, including sites in southern NE and IA, western MO and IL, and KS. In contrast, majority of sites in the northern and eastern fringe of the region are still in the late vegetative phases (ND, MN, northern IA and IL, MI, IN, and OH) as well as in northern and western NE (Figure 2). Most locations are running ahead last year’s corn development.

Figure 2. Simulated developmental stage for irrigated and rainfed corn at each location. Vn: vegetative stage (nth leaf); R1: silking; R2: blister; R3: milk. Separate maps are shown for irrigated corn (top) and rainfed corn (bottom).

Irrigated Corn: High Probability of Near-Average Yields

The range of forecasted irrigated corn yield potential for each location, as well as the probabilities for yields above, near, or below average, are shown in Figures 3 and 4. Although it is still too early in the season, there is a relatively high probability of near-average yields for all sites. Weather conditions during the rest of the growing season will determine if most irrigated sites will have near-average yield potential. The chance of below-average yield appears to be small for all irrigated sites except for one site (Silverlake, KS). Compared with the 2019 forecasts by mid-July, the forecasted scenario for irrigated maize seems more pessimistic in the current season.

Variable 2020 Forecasted Corn Yield Across Rainfed Locations

Forecasted yield potential is highly variable across rainfed sites (Figures 3 and 4). There is a high probability of below-average yield (>75%, that is, a chance of 3 out of 4) at two sites in south-central and eastern NE, while there is only one site with high probability of above-average yield (Eldred, MN). Overall, at this point of the season, probability of near-average yield is relatively high in the central area of the Corn Belt (southern MN, IA, IL, and IN). In contrast, the probability of below-average yields increases towards the western fringe of the region (NE, KS, and southwestern IA) but this may change depending on precipitation and temperature during the rest of July and August. Compared with the 2019 forecasts by mid-July, the forecasted scenario for rainfed maize seems more pessimistic in the western fringe of the Corn Belt (southwestern IA, NE, KS, and ND) in the current season. In the remaining area, the scenario looks similar to last year’s forecast at this point in the season.

Figure 3. 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 indicates the long-term (2005-2019) average yield potential at each location. Separate charts are shown for irrigated corn (top) and rainfed corn (bottom).
Figure 4. Probability of the 2020 yield potential to be below (<10%, red color), near (± 10%, yellow color), and above (>10%, green color) the long-term (2005-2019) average yield potential at each location. Separate maps are shown for irrigated corn (top) and rainfed corn (bottom). 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.

Conclusions

Corn is still in vegetative stages throughout most of the region. Although it is still too early to make strong inferences about end-of-season yields for irrigated corn, there is a relatively high probability for near-average yields for a majority of sites, but this can change depending upon temperature during the next 4 weeks. For rainfed corn, the scenario is diverse across regions, with higher probability of below-average yields in the western fringe of the region. Temperature and rainfall during the rest of July and early Aug will likely define the trend for all sites across the region. 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 the ones reported here in fields with planting dates or hybrid maturities that differ markedly from those used as the basis for the forecasts. We will follow up with further forecasts in early August.