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Research Discovers New Option for Cleaning Spray Tanks

Kali Elftmann, LSU research associate, conducts a laboratory experiment to determine how well a plant-based solubilizer cleans a spray hose model. Photo: Zhijun Liu

By Laura Temple

Herbicide-tolerant soybeans expand weed control options to include dicamba, 2,4-D and more. Yet many soybean varieties are still sensitive to herbicides that other varieties have been bred to tolerate. That means herbicide residue left in spray tanks and booms from a previous application can damage crops much like herbicide drift.

A new potential cleaning solution may be available from an unlikely source.

“While researching medicinal plants, I discovered natural ingredients that can solubilize a wide range of substances, or force oil and water to mix,” says Zhijun Liu, professor in the School of Renewable Natural Resources at Louisiana State University. 

These compounds can be used to deliver lipid-based pharmaceuticals. However, he also asked his agricultural-focused colleagues, including weed scientists James Griffin and Matthew Foster, if other potential applications existed for this discovery.

“One suggestion was learning if these solubilizers can clean herbicide residues from spray equipment,” he continues. “Some types of residues can’t be removed from sprayer tanks, booms, hoses and nozzles even with ammonia water or currently available commercial cleaning products.”

With soy checkoff funding from the Louisiana Soybean and Grain Research and Promotion Board, Liu and his team began investigating the potential for this plant-based spray tank cleaner. For the past few years, he has explored the use of these solubilizers to remove potentially damaging herbicide residues in both lab and real-world conditions.

As Liu started this research, he learned that herbicides can leave hard, dry, insoluble residues in equipment. Chemical manufacturers recommend triple-rinsing spray tanks, booms and nozzles to clean them. However, Liu heard from farmers that they rarely do this because it’s time-consuming and requires significant amounts of water. Plus, the wastewater from this method may not be environmentally friendly.

Kali Elfmann, research associate, and Dr. Zhijun Liu analyze rinsates, or used cleaning water, from experiments with a plant-based spray tank cleaner.

“And for some chemicals, this triple-rinse protocol isn’t adequate,” he says. “For example, 2,4-D acid ester in EC formulation may not be cleaned with this method even if the protocol is strictly followed. Farmers need both a better cleaner and a better cleaning method.”

Effective Cleaner

His team’s research on a botanical cleaner for spray equipment found that his formulations work better than current products. Made from the plant-based solubilizers he discovered, it effectively binds to residues from water-soluble and water-insoluble herbicides. Experiments found that the botanical cleaner solubilizes more than 100 active ingredients, including 2,4-D acid, flumioxazin and atrazine. 

Liu studied many other properties as well. For example, the botanical cleaner remains stable for at least three months, based on evaluations under refrigeration and at room temperature. And the natural solubilizers are safe for humans, animals and the environment.

New Cleaning Method

After confirming the effectiveness of the cleaner, Liu focused on developing a better cleaning method. 

“We learned that this cleaner could work well when added in just enough water to prime sprayer booms and hoses,” he reports. “If it sits for 18 to 24 hours, it effectively removes more than 90% of residue.”

This method does take time, but he found that the cleaner needs to sit for a while to work well. Based on his study, his method does need to sit at least overnight, with a longer time period working better than just six to eight hours.

Despite the drawback of the cleaning time, he believes these plant-based solubilizers provide a valuable solution for farmers, especially since the wastewater from cleaning with them has less environmental impact than the triple-rinse method.

“We are currently testing formulations with more types of crop chemicals, to verify that it will work for any type of herbicide,” Liu says. “Then we plan to explore potential for commercialization. We are willing to work with product developers to make this tool available for farmers and custom applicators.”

Published: Dec 5, 2022

This project was funded by the soybean checkoff. To find research related to this research highlight or to see other checkoff research projects, please visit the National Soybean Checkoff Research Database.