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#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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