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On Farm Research
As harvest rolls to a close you most likely noticed some field variability or have some questions about how various products or production practices may work on your farm. Every year during the winter, UNL Extension educators share research conducted by your peers-other farmers-in their own fields and often those presentations are very interesting to our clientele.
With the advance of farming technologies, it’s easier than ever for more farmers to conduct research on their own farms. Depending on the study, there may be additional time involved, but overall, the farmers I’ve worked with who have conducted on-farm research say they obtained answers to their questions and the power was knowing it was research based on their own farm.
Last winter the two on-farm research groups in Nebraska combined to form the Nebraska On-Farm Research Network. With help from the Nebraska Corn Growers and Nebraska Corn Board, three State-wide studies were rolled out in addition to other studies that producers wanted to conduct on their own farms. That data is still being collected and analyzed right now and results will be presented this winter.
So as you think about the 2012 season, what are the questions you have? Consider working with your local Extension Educator to design a valid research-based experiment to answer the questions on your farm. To learn more, please check out the CropWatch on-farm research page.
What studies would you like to see our group research on-farm in 2013?
#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.
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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 |
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|---|---|---|---|---|---|---|---|---|---|
| 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) | |||||||||
2011 Corn Yield Predictions
Harvest is nearly complete! In early August, I shared a post regarding in-season yield predictions from the Hybrid Maize
model. At that time, I showed how 2011 predicted yields had been tracking with the 30 year long term average yields up until early August. At that point, the 2011 predicted yields took a steep drop due to high night time temperatures. High night time temperatures don’t allow for the corn plant to shut down at night. The plant engages in respiration, essentially burning sugars that should be converted into yield.
Some interesting things happened with the weather this year to make yields more favorable than what once was predicted. While silking to beginning dent occurred in 20 days or less in several Nebraska fields this year, the weather cooled off during the filling process. Some fields stayed at ¼ starch for nearly three weeks. Looking at fields, kernels continued to get deeper, heavier, and expand to help cover some of the pollination problems observed earlier in the year. During this time, yield predictions from the Hybrid Maize model showed that yields had the potential of returning close to the long-term median
yields and it was interesting watching the trendlines move back up toward normal. This seemed to be truer for 113 day hybrids vs. 110 day hybrids.
For example, a 110 day hybrid planted April 15 at 32,000 seeds/acre showed a predicted yield of 227 bu/acre compared to 240 bu/acre long-term median. But a 113 day hybrid planted the same day showed a predicted yield of 244 bu/acre compared to a 248 bu/acre long term median yield.
So what happened in your fields? While yields have been decent, on average, I’m not seeing the trend towards the long-term median yields in our area in general. Dryland yields I think have been better than expected but irrigated yields potentially not as good as anticipated by many. 
Hybrid Maize predicts yields based on perfect conditions-nothing limiting and no pest/disease issues. In many fields, corn was planted then sat in cool, wet soils. We had stand losses due to Pythium in some fields or due to loose residue that was piled in areas of fields after heavy rains. We also had varying degrees of pollination problems and the high night temperature stresses which reduced yields. Regardless, yields are still very good in spite of another interesting growing season! Please share what you’ve been seeing for yields in your fields!
Table 1: Hybrid Maize 2011 Predictions from Simulations (through Oct. 30, 2011)
Date RM Population Long-Term Median Yield 2011 Predicted Yield
Apr. 15 110dy 32,000 240 bu/acre 227 bu/acre
Apr. 15 113 dy 32,000 248 bu/acre 244 bu/acre
May 1 110dy 32,000 241 bu/acre 234 bu/acre
May 1 113dy 32,000 260 bu/acre 245 bu/acre
May 10 110dy 32,000 244 bu/acre 235 bu/acre
May 10 113dy 32,000 258 bu/acre 258 bu/acre
JenResources 