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Latest 2012 #Corn Yield Predictions

2012 Corn Yield Potential Forecast Based on Aug. 27 Hybrid-Maize Simulation:  Irrigated corn yield potential is predicted to be 2-8% below long-term average, while dryland yield potential in much of the Corn Belt will be moderately to severely reduced, falling 22-67% below normal. Predictions are assuming no stress during pollination and fully irrigated fields with no equipment, disease, or insect problems.
Map of sites used for yield forecasts

Figure 1. Locations used by the Hybrid-Maize model for in-season yield forecasting with actual weather and dominant management practices and soil series at each site (indicated by stars).  Green areas indicate where corn is planted.  Weather data used is from the High Plains Regional Climate Center and the Water and Atmospheric Resources Monitoring Program through the Illinois Climate Network (Illinois State Water Survey, Prairie Research Institute, and the University of Illinois at Urbana-Champaign). Link to a larger version of Figure 1. 

Simulations were run for dryland corn in Iowa, Illinois, and South Dakota, and for both irrigated and dryland corn in Nebraska. Simulations were based on the typical planting date, hybrid relative maturity, plant population, and soil properties at each location. Underpinning data used in these simulations are provided in Table 1. To evaluate the impact on potential production at 12 sites across the Corn Belt (Figure 1), we used the Hybrid-Maize model  to estimate end-of-season yield potential based on actual weather up to August 27, and historical long-term weather data to complete the season using data from each of the past 30 years. This approach gives a “real-time,” in-season estimate of expected yield potential (the median value shown in Table 1) depending on weather conditions from August 27 until the corn crop reaches maturity.

August 27 projections give a narrower range than our projections based on August 13 simulations, and, at some locations the crop reached blacklayer during the past week (Mead, Concord, O’Neill, and Nashua, Iowa). Projected yield potential since August 13 has not changed by more than 7% across all locations, except for the two locations in west central Illinois (Monmouth) and south central Illinois (Bondville) where predicted dryland yield has increased by 30% due to good rains and cooler weather. It should be noted, however, that if unusually hot, dry weather occurred during pollination at these Illinois locations, such a large yield improvement would not be expected due to reduced seed set. Still, projections of final yield potential are below the long-term average at all sites, under both irrigated and dryland conditions (Table 1).

The bottom line is that 2012 irrigated yields will be moderately lower than the long-term averages (2-8% below normal), while dryland corn yield potential in much of the Corn Belt will be moderately to severely reduced (22-67% below normal). It is important to keep in mind that yields can be even lower at places where both prolonged drought and high temperature stress at pollination have occurred. Also, greater field-scale variability is being observed this year in irrigated fields due to the inability of some irrigation systems to keep up with crop water use demand, problems with pivot irrigation nozzles and uneven watering, and additional stresses from insects and diseases. Such problems can contribute to reduced yields at irrigated sites of more than the 2-8% simulated by the model.There is a modest yield loss (5-8%) for locations in South Dakota (Brookings) and west central and north central Illinois (Monmouth and DeKalb) while a moderate yield loss of 22-28% is predicted for dryland corn in central and northeast Iowa (Gilbert and Nashua). Severe yield loss of 32-67% is projected for dryland corn in south central, eastern, and northeastern Nebraska (Clay Center, Mead, and Concord), northwest Iowa (Sutherland), and south central Illinois (Bondville) (Table 1). In contrast to large loss of yield potential in these dryland systems, the projected losses in yield potential at all irrigated sites are modest at about 2-3% in south central Nebraska (Clay Center, Holdrege), and 7-8% in east and northeast Nebraska (O’Neill, Concord, and Mead) (Table 1). Projected irrigated yield potential since August 13 has increased by about 3% due to cooler weather during the past two weeks.

Patricio Grassini, Research Associate Professor, Agronomy and Horticulture Department
Jenny Rees, UNL Extension Educator
Haishun Yang, Associate Professor, Agronomy and Horticulture Department
Kenneth G Cassman, Professor, Agronomy and Horticulture Department

Earlier Hybrid-Maize Predictions

Table 1.  2012 In-season yield potential forecasts as of August 17  using UNL Hybrid-Maize Model

Location, State Water Regime Soil Type&
Initial Water
Plant
Pop.
(ac-1)
Relative
Maturity
(days)
Planting Date Long-term
Yp
(bu/ac)
2012 Forecasted Yp (bu/ac)
 Median  

Holdrege, NE Irrigated Silt loam 32.4k 113  April 27  248
243  
Clay Center, NE Irrigated

Rainfed

Silt clay loam

100% ASW

32.4k

24.0k

113 April 23

April 23

 250
146
242
98
 
Mead, NE Irrigated

Rainfed

Silt clay loam

100% ASW

32.4k

28.0k

113  April 30  240
160
224
53
 
Concord, NE Irrigated

Rainfed

Silt loam

100% ASW

32.4k

29.0k

104 May 3 235
154
218
90
 
O’Neill, NE Irrigated Sandy loam

100% ASW

32.4k 106  May 3 225
207   

Brookings, SD Rainfed Silt clay loam

100% ASW

30.0k 98  May 4 120
110   

Sutherland, IA Rainfed Silt clay loam

100% ASW

31.4k 99  May 1 168
104    
Gilbert, IA Rainfed Loam

100% ASW

32.4k  110  April 26 200
145
 
Nashua, IA Rainfed Loam

100% ASW

32.4k 99  May 1 198
155  

Monmouth, IL Rainfed Silt loam

100% ASW

32.4k 112  April 27 212
189   
DeKalb, IL Rainfed Silt clay loam

100% ASW

32.4k 111  May 1 201
190
Bondville, IL Rainfed Silt clay loam

100% ASW

32.4k 114  April 20 197
134   

  Simulations based on dominant soil series, average planting date, and plant population (PP) & relative maturity (RM) of most widespread hybrid at each location (Grassini et al., 2009). 

 Average (20+ years) simulated yield potential (Yp). 

Latest 2012 #Corn Yield Predictions

The 2012 corn growing season has been unusually hot and dry. To evaluate the impact on potential production at 12 sites across the Corn Belt, we used the Hybrid-Maize model to estimate end-of-season yield potential based on actual weather up to August 13 and historical long-term weather data thereafter. (Data  from each of the past 30 years was used.) This approach gives a “real-time,” in-season estimate of expected yield potential (the median value shown inTable 1), and the most probable range (25th to 75th percentiles) depending on weather conditions from August 13 until the corn crop reaches maturity.

By comparing this range of possible simulated end-of-season yield potential against the long-term average (long-term Yp, fourth column from right in Table 1), it is possible to estimate the likelihood for below-average (25th percentile), average (median), or above-average (75th percentile) yields. Comparing estimated 2012 yield potential versus the long-term average gives the size of the expected yield difference. While the 25th percentile projection is most likely if weather conditions are harsher than normal from August 13 until crop maturity, the 75th percentile scenario is more likely if weather is more favorable than is typical at a given site. There is roughly a 50% probability that final yield potential will fall between the 25th and 75th percentile levels, a 75% chance that yield will be at or below the 75th percentile, and a 25% probability that it will be at or below the 25th percentile value.

Simulations were run for dryland corn in Iowa, Illinois, and South Dakota, and for both irrigated and dryland corn in Nebraska. Simulations were based on the typical planting date, hybrid relative maturity, plant population, and soil properties at each location. Underpinning data used in these simulations are provided in Table 1. Details about the Hybrid-Maize model and our simulation forecast methods can be found in a previous CropWatch article.

As the season progresses, the range of yield outcomes shrinks and the 25th and 75th percentile values converge toward the median value. Indeed, August 13 projections give a much narrower range than our projections two weeks earlier based on July 30 simulations. The good news is that projected yield potential since July 30 has stabilized or even increased slightly at 7 of 12 sites as weather has improved, especially during the most recent week. The bad news is that projections of final yield potential are below the long-term average at all but two sites.

Dryland Corn

Even in hot, dry years like 2012, parts of the Corn Belt escape untouched and catch adequate rainfall. This appears to be the case in the northern tier of the Corn Belt (e.g. Brookings, South Dakota) and near the Great Lakes (e.g. Dekalb, Illinois) where projected dryland yield potential is within 2% of the long-term average. In contrast, there is moderate yield loss of 26-33% for dryland corn in south central Nebraska (Clay Center), central and northeast Iowa (Gilbert and Nashua), and west central Illinois (Monmouth). Severe yield loss of 40-65% is projected for dryland corn in eastern and northeastern Nebraska (Mead, Concord), northwest Iowa (Sutherland), and south central Illinois (Bondville).

Irrigated Corn

In contrast to large loss of yield potential in these dryland systems, drought years like 2012 highlight the value of irrigated agriculture and the stability it provides to our food system. Although hotter than average temperatures have shortened the grain filling period at all irrigated sites, which reduces yield potential somewhat, projected decreases are modest at about 5% in south central Nebraska (Clay Center, Holdrege), and 10% in east and northeast Nebraska (O’Neill, Concord, Mead). High grain prices are likely to offset the impact such losses will have on profits from irrigated corn.

Model Reliability

Given the severity of reductions in yield potential at some locations, and the apparent lack of negative impact at others, the question arises as to how reliable these projections are? In areas with relatively little heat or water stress, past experience indicates that predictions of yield potential using Hybrid-Maize are robust. In contrast, we would expect predictions of yield loss to be underestimated by Hybrid-Maize in areas where there was high temperature stress during the critical two to three day period of pollination, or where there were large water deficits that severely reduced development of the leaf canopy before tasseling. Both phenomena are not well accounted for in the current version of the model although we plan to release an improved version of Hybrid-Maize later this year that addresses these deficiencies.

Summary

The bottom line is that 2012 will be a difficult year in terms of U.S. corn production. Although irrigated yields will be somewhat lower than long-term averages, dryland corn yield potential in much of the Corn Belt will be moderately (25-33% below normal) to severely reduced (40-65% below normal). Where both prolonged drought and high temperature stress at pollination occurred, yields could be reduced by 65% or more. The final outcome will be determined by weather conditions until maturity. Fortunately, predicted weather patterns indicate a trend toward more normal temperatures and rainfall in many places.

While 2012 will certainly be a significant drought year, episodic droughts of this magnitude have occurred at regular intervals in the U.S. Corn Belt over the past 100 years of recorded weather data. Nebraska is fortunate that about 70% of total corn production comes from irrigated systems, and that improved agronomic management practices such as conservation tillage and more stress-tolerant hybrids can significantly reduce dryland corn yield losses under moderate drought. But there is little that can be done to mitigate the impact of severe, prolonged drought especially when coupled with high temperature stress at critical growth periods.

Patricio Grassini, Research Associate Professor, Department of Agronomy and Horticulture
Jenny Rees, UNL Extension Educator
Haishun Yang, Associate Professor, Department of Agronomy and Horticulture
Kenneth G Cassman, Professor, Department of Agronomy and Horticulture

Table 1.  2012 In-season yield potential forecasts as of August 13  using UNL Hybrid-Maize Model

Location, State

Water Regime

PP(ac-1)

RM¶ (days)

Planting Date

Long-term
Yp (bu/ac)

 2012 Forecasted Yp (bu/ac)

 75th*

 Median


Holdrege, NE

Irrigated

 32.4k

113

 April 27

 248   

 239

 232

Clay Center, NE

Irrigated
Rainfed

32.4k
24.0k

113

April 23
April 23

 250
146   

241
115

237
104

Mead, NE

Irrigated
Rainfed

32.4k
28.0k

113

 April 30

 240
160   

221
60

216
56

Concord, NE

Irrigated
Rainfed

32.4k
29.0k

104

May 3

235
154   

210
92

208
86

O’Neill, NE

Irrigated

 32.4k

106

 May 3

225   

 212

203


Brookings, SD

Rainfed

 30.0k

98

 May 4

120   

 127

118


Sutherland, IA

Rainfed

 31.4k

99

 May 1

168   

 110

99

Gilbert, IA

Rainfed

 32.4k

 110

 April 26

200   

 157

144

Nashua, IA

Rainfed

 32.4k

99

 May 1

198   

 152

147


Monmouth, IL

Rainfed

 32.4k

112

 April 27

212   

 161

143

DeKalb, IL

Rainfed

 32.4k

111

 May 1

201   

 227

204

Bondville, IL

Rainfed

 32.4k

114

 April 20

197   

 110

105


  Simulations based on dominant soil series, average planting date, and plant population (PP) and relative maturity (RM) of most widespread hybrid at each location (Grassini et al., 2009).
 Average (20+ years) simulated yield potential (Yp).
* 75th percentile yields, which represent favorable and unfavorable weather scenarios for the rest of the season.

#Corn yield predictions across the corn belt

A follow-up to my last blog post predicting corn yields for our local area this week in south-central Nebraska.  Here’s some 2012 yield predictions for throughout the corn belt from an article my colleagues in Agronomy and Horticulture and I posted this week’s CropWatch newsletter.

July 10, 2012

Forecasted Corn Yields Based on Hybrid-Maize Model Simulations

Most Sites, Except Northeast, Dip Below Long-term Average Yields

The weather is hot, dry, and windy. Corn is pollinating in much of the state and growers are asking how the weather will impact potential corn yields for 2012. To answer this, we ran in-season corn yield predictions using the Hybrid-Maize Model developed by researchers in the UNL Department of Agronomy and Horticulture. This model simulates daily corn growth and development and final grain yield of corn under irrigated and rainfed conditions.

Corn Belt map showing areas of data collection for Hybrid-Maize Prediction

Figure 1. Locations used by the Hybrid-Maize model for in-season yield forecasting with actual weather and dominant management practices and soil series at each site (indicated by starts).  Green areas indicate where corn is planted.  Weather data used is from the High Plains Regional Climate Center and the Water and Atmospheric Resources Monitoring Programthrough the Illinois Climate Network (Illinois State Water Survey, Prairie Research Institute, and the University of Illinois at Urbana-Champaign).  (See larger version of Figure 1 andTable 1)

Compare with 2011 Forecasts in CropWatch

Similar models were run with Hybrid-Maize in 2011.  See the results in these CropWatch stories:

The Hybrid-Maize model predicts yields based on no nutrient limitations, no disease or insect pressure and an “optimal management” scenario. Hybrid-Maize is helpful in understanding how current in-season weather conditions are affecting corn growth and potential yield for the current year and in comparison to previous years.

Hybrid-Maize model can be used during the current crop season to forecast end-of season yield potential under irrigated and rainfed conditions. To do so, Hybrid-Maize uses observed weather data until the date of the yield forecast and historical weather data to predict the rest of the season. This gives a range of possible end-of-season yields. This range of simulated yields narrows as corn approaches maturity.

Hybrid-Maize was used around July 1 to predict 2012 end-of-season corn yield potential throughout the Corn Belt, including locations in Nebraska, Iowa, South Dakota, and Illinois (Figure 1). Sites in Nebraska include Holdrege, Clay Center, Mead, Concord, and O’Neill. Separate yield forecasts were performed for irrigated and dryland corn for those sites where both irrigated and rainfed production is important (in Nebraska: Clay Center, Mead, and Concord). Underpinning inputs used for the simulations include weather data provided by the High Plains Regional Climate Center (HPRCC) and the Illinois Water and Atmospheric Resources Monitoring Program (WARM) and site-specific information on soil properties and typical crop management (planting dates, hybrid maturity, and plant populations).

Corn Yield Potential (Yp) forecasts, as well as the underpinning data used for the simulations, can be seen inTable 1. The long-term, predicted yield potential based on 30 years of weather data (fourth column from the right) is then compared to the range of predicted 2012 corn yield potential (three columns on the right), which includes the yield potential simulated under the most likely scenario of weather expected for the rest of the season (median) and for relatively favorable and unfavorable scenarios for the rest of the season (75th and 25th percentiles) based on historical weather data.

In general, when comparing the median predicted yield for 2012 to the long-term, 30-year average yield potential, 2012 yields are trending lower than the long-term yields (Table 1). Below-normal rainfall coupled with high rates of daily water use due to high daytime temperatures, are the factors leading to the below-average yield potential predicted by Hybrid-Maize for dryland corn across the Corn Belt. An exception is Brookings, S.D. where rainfall has been favorable so far and rates of water use are relatively low compared with other locations.

In the case of irrigated corn in Nebraska, the model is predicting a median yield potential six to seven bushels below the long-term average irrigated yield potential at Holdrege, Clay Center, and Mead due to above-normal temperatures which hasten crop development and increase night respiration. However, this is not consistent throughout the state.  Predictions of irrigated corn yield potential are only slightly below (Concord) or even above (O’Neill) the long-term average in northern Nebraska due to cooler weather.

These are simulations and again are based on optimal conditions for crop growth, that is, no limitations by nutrients and no incidence of diseases and insects. Nevertheless, they provide an idea on how in-season weather conditions can impact corn yield potential under irrigated and rainfed conditions. Last year, we saw a similar situation when in-season yields dropped off from the long-term average due to extreme high temperatures by late July and then climbed back up with cooler night temperatures and a long grain-filling period in August. These yield predictions are based on a snapshot in time. Actually, in the current 2012 season, there is still a good chance of having a near or above-average corn yield potential at locations where weather conditions are favorable during the rest of the season as indicated by the 75th percentile yields shown in Table 1. However, if hot, dry conditions continue through much of July, we would expect yield predictions to fall. We will follow-up with predictions later on in the season.

Patricio Grassini, Research Assistant Professor, UNL Department of Agronomy and Horticulture
Jenny Rees, UNL Extension Educator
Haishun Yang, Professor, UNL Department of Agronomy and Horticulture
Ken Cassman, Professor, UNL Department of Agronomy and Horticulture

Table 1. 2012 In-season Yield Potential Forecasts using UNL Hybrid-Maize Model
Location, state Water regime Soil type¶ & initial water PP¶ (ac-1) RM¶ (days) Planting date† Long-term yield potential (bu/ac)‡ 2012 forecasted yield potential (bu/ac)
75th Median 25th
Holdrege, NE Irrigated Silt loam 32.4k 113 April 27 248 257  241 228
Clay Center, NE Irrigated

Rainfed

Silt clay loam

100% ASW

32.4k

24.0k

113 April 23

April 23

250

146

263
153
244
123
232
103
Mead, NE Irrigated

Rainfed

Silt clay loam

100% ASW

32.4k

28.0k

113 April 30 240

160

251
173
234
145
218
129
Concord, NE Irrigated

Rainfed

Silt loam

100% ASW

32.4k

29.0k

104 May 3 235

154

244
180
232
148
223
110
O’Neill, NE Irrigated Sandy loam

100% ASW

32.4k 106 May 3 225 255 231 221
Brookings, SD Rainfed Silt clay loam

100% ASW

30.0k 98 May 4 120 150 132 99
Sutherland, IA Rainfed Silt clay loam

100% ASW

31.4k 99 May 1 168 190 157 127
Gilbert, IA Rainfed Loam

100% ASW

32.4k 110 April 26 200 227 187 171
Nashua, IA Rainfed Loam

100% ASW

32.4k 99 May 1 198 225 191 156
Monmouth, IL Rainfed Silt loam

100% ASW

32.4k 112 April 27 212 229 186 161
DeKalb, IL Rainfed Silt clay loam

100% ASW

32.4k 111 May 1 201 252 197 165
Bondville, IL Rainfed Silt clay loam

100% ASW

32.4k 114 April 20 197 206 156 140
 ¶ Simulations based on dominant soil series, average planting date, plant population (PP) and relative maturity (RM) of most widespread hybrid at each location (Grassini et al., 2009), assuming 100% available soil water in the top 40 inches at the beginning of the growing season. ‡ Average (20+ years) simulated yield potential (Yp)

2012 #Corn Yield Predictions

The past few weeks I’ve received questions on how the weather conditions are impacting corn yields.  One way to help predict this is by running the Hybrid Maize model developed by researchers in the Agronomy and Horticulture Department at UNL.  I ran Hybrid Maize model simulations for various planting dates in the Clay Center, NE area.  This model predicts corn yields using weather data under “perfect conditions”-nothing such as nutrients or water is limited and there is no disease or insect pressure in these simulations.  Reality is that all these things do occur.  To use the model, I input current season weather data from the High Plains Regional Climate Center which allows me to compare the current growing season weather conditions and potential yield impacts to a long term median 30 years worth of weather and yield data.  

For the simulations I ran right now using Clay Center weather data, I found that overall, we are trending below the 30 year median average yields for both irrigated and rainfed corn.  Right now the long-term median yield for all irrigation simulations is trending towards 259 bu/ac at planting populations of 32,000 seeds/acre with 113 or 115 day relative maturities.  The following are a few simulations and please check out this week’s CropWatch to view simulations across the Corn Belt.  Click on the images below to view them closer up.  Compare the 2012 median yield line (in red) to the long-term median line (yellow).

  • Mar. 27 planting date, 115 day rm:  Best yield 300 bu/ac.  Predicted mean is 241 bu/ac.

  • Apr. 15 planting date, 113 day rm:  Best yield 293 bu/ac.  Predicted mean is 242 bu/ac.

  • Apr. 15 planting date, 115 day rm:  Best yield 200 bu/ac.  Predicted mean is 253 bu/ac.

  • May 1 planting date, 113 day rm:  Best yield is 286 bu/ac.  Predicted mean is 248 bu/ac.

  • May 1 planting date, 115 day rm:  Best yield is 293 bu/ac.  Predicted mean is 252 bu/ac.

  • May 15 planting date, 113 day rm:  Best yield is 310 bu/ac.  Predicted mean is 253 bu/ac.

The best comparison is the predicted mean to the long-term median so right now we’re seeing a slight drop below the long-term median for all the planting dates and relative maturities run in these simulations.  However, if we receive cooler night-time temperatures and a longer fill period like last year, we may see these yield trends turn up.

For rainfed conditions, I did not run optimal simulations.  I ran real-time water limited situations assuming full soil moisture from 0-40” into the profile at the beginning of the season.  Here are the results for a planting population of 22,000 plants/acre with 113 day relative maturities:

  • Mar. 27 planting date, 115 day rm:  Best yield is 202 bu/ac.  Predicted mean is 140 bu/ac vs. long term median of 163 bu/ac.

  • April 15 planting date, 113 day rm:  Best yield is 224 bu/ac.  Predicted mean is 146 bu/ac vs. long term median of 167 bu/ac.

  • May 1 planting date, 113 day rm:  Best yield is 223 bu/ac.  Predicted mean is 152 bu vs. long term median of 167 bu/ac.

  • May 15 planting date, 113 day rm:  Best yield is 250 bu/ac.  Predicted mean is 161 vs. long term median of 165 bu/ac.

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