One of the pressing questions this fall is when will corn reach maturity? Will there be enough time for corn grain to dry down in the field?
“We have developed and released a corn grain drydown calculator that can help determine how quickly corn grain moisture will dry down in the field,” says Iowa State University Extension cropping systems agronomist Mark Licht. “The calculator can be applied at any location across the Corn Belt, from North Dakota to Missouri and from Nebraska to Ohio. Users select a map location and then enter a date and a kernel moisture content at that date. In turn, the tool projects in-field corn drydown.”
This tool can be used to estimate when a specific field will reach appropriate moisture content for mechanical harvest (15% to 20% corn grain moisture) based on user input, explains Sotirios Archontoulis, an ISU agronomy professor who works with Licht.
The tool allows scenario planning by entering estimated dates and grain moisture for crops that are yet to mature compared to fields where crops have already matured. This is facilitated by the user’s ability to enter known (or estimated) dates and grain moisture.
Help with harvest schedule
Licht and Archontoulis provide an example of how to use and interpret the tool. This is a field in Story County in central Iowa that reached black layer on Sept. 15 at 30% grain moisture. In this situation, it is estimated that on Sept. 19, grain moisture will be 24.8% and on Sept. 24, it will be 21.8%. Furthermore, the grain drydown rate is estimated to slow down after Oct. 1.
This tool prediction uses the daily temperature and relative humidity as the input for an algorithm developed from a multiyear, multi-location research trial in Iowa. The algorithm development research report can be found at Evaluating maize and soybean grain drydown in the field with predictive algorithms and genotype-by-environment analysis. Where possible, current temperature and relative humidity data is used, Archontoulis says. Forecasting beyond the current date is based on historical temperature and humidity information.
Tool considers weather conditions
“The effect of precipitation on drydown of the grain in the field is indirectly captured by relative humidity, whereby on rainy days the drying power of the air is low, which is reflected by high relative humidity,” Archontoulis says.
He adds, “We tested the prediction using data spanning from eastern North Dakota to southern Iowa, and the tool predicted moisture decline with an error of 1.8%. The tool is best-suited and recommended for use when crops reach physiological maturity; however, predictions can be made before that point.”