Tech Reduces Runoff Pollution By Making Spray Droplets Less Bouncy

When farmers spray their fields with pesticides or other treatments, only 2 percent of the spray sticks to the plants while a significant portion becomes part of the runoff that flows to streams and rivers - often causing serious pollution. MIT researchers have developed a way to make droplets less bouncy, which could help drastically cut down on the amount of pesticide liquid that bounces off plants. The new approach uses two different kinds of additives. The spray is divided into two portions, each receiving a different polymer substance. One gives the solution a negative electric charge; the other causes a positive charge. When two of the oppositely-charged droplets meet on a leaf surface, they form a hydrophilic (water attracting) 'defect' that sticks to the surface and increases the retention of further droplets.

Transcript

00:00:00 [MUSIC PLAYING] Spraying fields with pesticides or other treatments is a common practice among farmers. However, it turns out only 2% of what is sprayed actually sticks to the plants. A significant portion of what is sprayed bounces right off. This not only defeats the purpose of spraying in the first place, but it can also be quite damaging in the form of pollution

00:00:23 to the surrounding lands and waterways. But now, by using a clever combination of polymer additives, a team of MIT researchers have developed a method of spray that can drastically cut down the amount of liquid that bounces off the plants. The new approach uses two different kinds of additives. One gives the solution to be sprayed a negative electrical charge, while the other causes a positive charge. When the two oppositely charged droplets

00:00:47 meet on the leaf surface, they form a hydrophilic, or water-attracting, film that sticks to the surface and increases the retention of further droplets. Their new approach would require only minor changes to the existing equipment that farmers use. And since the cost of pesticides can be a significant part of a small farmer's budget, reducing the amount that is wasted could improve the overall economics

00:01:08 of the farming business. Furthermore, preventing bouncing and reducing the amount of pesticide sprayed can also reduce the exposure of farmers to the spray chemicals. The polymers used are extracted from common, low-cost materials and could be produced locally. And they are also natural and biodegradable, so they will not contribute to the runoff pollution.