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.