Research HighlightsReal-Time Weather Data for Spray Applications
Provided by the South Dakota Soybean Checkoff
When concerns surrounding dicamba drift surfaced for soybean producers around 2015, the need for access to accurate, real-time information about weather conditions became urgent.
“The kind of weather data that applicators needed to know to comply with the dicamba label basically wasn’t available,” explains Laura Edwards, South Dakota State University Extension Climatologist. That’s when South Dakota Soybean Research and Promotion Council partnered with SDSU Extension and SDSU’s Mesonet initiative to develop a user-friendly tool to report on localized conditions for spray applications.
A State-of-the-Art Reporting System
“We’re collaborating on this to provide real-time weather data for pesticide applicators,” says Edwards. Paid for by South Dakota soybean farmers through their checkoff, the Mesonet Spray Tool features a website built for desktop and mobile devices that shares up-to-date information on key measurements recorded at each of the state’s 49 weather stations. These recordings include:
- 3-ft Wind Speed: This measures the wind speed at the standard boom height for spray applications, which can sometimes vary dramatically from general wind speeds.
- Inversions: An inversion occurs when the air mass closer to the ground exhibits an air temperature that is lower than that of the air mass above it. This can cause dicamba droplets to remain within the air mass and thereby facilitate drift.
- ∆T (Delta T): Delta T is a means of measuring the humidity levels within the atmosphere and is useful in determining evaporation rates for droplets.
- Precipitation: The level of precipitation – both actual (since midnight) and forecast — in your region can help guide application decisions as well.
The inversion values were particularly important to Edwards and her team. “With support from South Dakota Soybean, we deployed additional thermometers out on the weather stations at that time to directly measure temperature inversion,” she says.
As noted above, an inversion occurs when the air temperature close to the ground is cooler than the air above it. “If you are spraying pesticide in an inversion, those droplets can basically stay airborne until there is wind,” says Edwards. “And that’s what can cause drift – when those droplets stay airborne and then blow to a neighbor’s farm or another field and potentially cause damage.”
Access Real-Time Data As Well As Forecast Values
Edwards points out that the Mesonet Spray Tool updates measurement data every 5 minutes; forecast values are updated hourly. The forecast feature is relatively new to the tool, providing producers and applicators with a better picture of conditions over the next 24 hours to aid with planning.
When visiting the Mesonet Spray Tool website, users can enter their specific location or browse the map to access site-specific information. Another feature worth noting is the ability to take a snapshot of weather data and send it to your personal email address by using the Record by Email button in the upper right corner of each location’s page.
Mesonet Expansion is in the Works
“With the Mesonet expanding to 150 stations or so statewide over the next few years, we’re going to be able to provide even more accurate data specific to locations all across the state,” says Edwards, acknowledging the support of farmers through their checkoff.
Published: Feb 3, 2025
The materials on SRIN were funded with checkoff dollars from United Soybean Board and the North Central Soybean Research Program. To find checkoff funded research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.
