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Map Tracks Cases of Chemical Drift

Agriculture chemicals are a tool to keep pests out of fields or yards, but drifting pesticides or herbicides are a concern for farmers and their neighbors.

According to the National Agricultural Statistics Service, Iowa farmers apply herbicide to 97 percent of corn acres and 95 percent of soybean acres. Nearly 77 percent of Iowa's 26 million acres of agriculture land was treated with pesticide. In that area, there are an average 78 cases of drift a year.

The University of Iowa's Great Plains Center for Agricultural Health is looking at those numbers and trying to help reduce it. Center Coordinator Jenna Gibbs helped research and map out all the cases of drift reported to the Iowa Department of Agriculture and Land Stewardship from 2010 to 2015.

Gibbs says, "Just by looking at the individual pieces on the map and scrolling through them and seeing what the target crop was can really show us a lot of lessons for how to prevent this from happening again in the future."

The map can zoom in to a county by county level and see individual cases. It looks at what was the target crop, how the application happened, and what chemical it used.

A county like Des Moines sees urban pesticide drift, where some counties did not have any cases reported. Gibbs says it can heal teach the right weather conditions, when to spray and what engineering controls are needed. Drift not only can waste money, it also raises concerns on the health impact to people and livestock.

Gibbs says a quarter of drift cases involved human exposure, "A lot of people's fields go right up to their neighbor, so kind of one of the biggest lessons we learned about this is just having that neighborly communication. Talking to your neighbors, letting them know the day that you're going to spray and things like that so you can avoid those potential human exposures."

Gibbs also found that high humidity reduces drift, 70 percent of drift cases happened with ground equipment versus aerial application, and that manufacturers' recommendation that pesticides be applied at wind speeds lower than 10 miles per hour is correct.

The majority of drift cases reported, happened when wind speeds were between 10 and 25 miles per hour.

She says Iowa is a gusty state and suggests farmers rely on personal wind tracking machines, "Microclimates are very important. Just because your cellphone weather app says that the wind's blowing eight miles per hour, that may not be the conditions that you're seeing on the farm."

You can look at the map here: https://uiowa.maps.arcgis.com/apps/MapJournal/index.html?appid=783dbfde24014d1fb8875a376ce7023f

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