Mesh helps reduce pesticides

An innovative mesh devised by MIT researchers could help farmers dramatically reduce the amount of pesticides they spray.

When spraying fertilizers or pesticides onto crops, the size of the droplets makes a big difference. Bigger drops will drift less in the wind, allowing them to strike their intended targets more accurately, but smaller droplets are more likely to stick when they land.

Typically, less than five per cent of sprayed liquids actually stick to their intended targets. The rest is lost to drift or never even gets there, and the other half bounces away.

Now, a team of MIT researchers has found a way to balance these properties and create sprays that do not drift too far but provide tiny droplets to stick to the surface, announced a statement. It is based on a fine mesh placed between the spray and the intended target to break up droplets into one-thousandth the size.

The new advance is based on atomizers, or devices that can spray liquids in the form of tiny droplets, but with the initial spray in the form of larger drops, which are much less affected by breezes. Finer droplets are created just before they reach the surface by inserting a mesh screen.

“The big motivation is agriculture,” explained MIT associate professor Kripa Varanasi. “The runoff of pesticides that miss their target and fall on the ground can be a significant cause of pollution and a waste of the expensive chemicals. What’s more, the impact of finer droplets is less likely to damage or weaken certain plants.”

Farmers already cover some crops with fabric meshes to protect against birds and insects. But what matters is the size of the openings in the mesh and the material’s thickness, according to the researchers, who have quantified the precise parametres.

The presence of the mesh over the crops could also protect them from damage from rainstorms, by breaking up raindrops into smaller droplets that place less stress on the plant when they strike, explained the statement.

The process may also reduce the problem of drift of pesticides, which sometimes blow from one farmer’s field to another, and even from one state to another, added Varanasi.

Photo credit: benjamin/ CC BY-NC-ND 2.0

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