Across Iowa, corn pollination is now complete and grain fill is well underway. Some people are actually walking out into fields and making yield estimates. Others are driving down the road, gazing at the fields and making yield "guestimates."
On July 20 an article was written by Iowa State University Extension agronomist Mark Licht, with input from fellow ISU agronomists, titled Corn Yield Predictions and posted on the ISU Integrated Crop Management newsletter website. He wrote the article to provide an insight into corn yield forecasts, how they are made based on the weather that occurs and the management that is used through the pollination period.
Today, Licht and his fellow agronomists at ISU Extension have updated that previous article. In the following article they update and discuss their revised corn yield forecast now that grain fill is underway. The July 20 article gives the background on the collaborative team at ISU that is working on this project, and explains the management and location assumptions they put in the Hybrid-Maize model.
Iowa farmers are looking at a big corn crop in 2014
The newly revised yield forecast for 2014 is based on current weather up to August 15 and historical weather thereafter. For Iowa, the median forecasted yields of the six locations ranged from -4% to 42% of the long-term average yield potential (See Table 1). The biggest deviation from the long-term average is the Lewis location where the yield projections indicate a 75% probability that yields near Lewis will be 27% or more above the normal yield. This represents the largest change from the July 20 article.
CORN YIELD POTENTIAL: This table shows the in-season yield potential forecasts for this growing season in Iowa. Yield predictions are made using the Hybrid-Maize model with current weather parameters prior to August 15, 2014 followed by historical weather records for the remainder of the growing season. Download revised corn yield forecast chart.
Yield projections at the Sutherland location were revised lower with a 50% probability of yields 6% above to 13% below the projection. Likewise, reductions in yield projections occurred at Kanawha and Nashua. These reductions in forecasted yields across the northern Iowa locations come from cooler weather and increased risk of a killing frost before maturity is reached.
Iowa has 75% probability of harvesting 231 bu. per acre
The full version of the July 20 simulation for all Corn Belt locations forecasted can be found at: "2014 Forecasted Corn Yields" Based on July 20 Hybrid Maize Model Simulations.
The best determination of yield potential for your farm will be by determining (or estimating) the yield components for your fields, says Licht. The most common yield calculations include; ears per acre, kernels per ear (rows per ear time kernels per row), and kernels per bushel (often as 90,000 kernels per bushels). Better estimates are achieved when conducting estimates based on 10 ears per stop and 10 stops per field with adjustments adjustment made to kernels per bushel for kernel weight and/or size.
Acknowledgements: The data presented here is part of larger yield forecasting project coordinated by Patricio Grassini, Haishun Yang, Roger Elmore and Kenneth Cassman from the Department of Agronomy and Horticulture, University of Nebraska-Lincoln and the Robert B. Dougherty Water for Food Institute.