MIT engineers have unveiled a revolutionary spray technology that reduces pesticide waste, decreases costs and enhances agricultural efficiency by ensuring droplets stick to plant leaves. This breakthrough could transform farming practices and sustainability.
Reducing the amount of agricultural sprays used by farmers could decrease polluting runoff, while at the same time cutting farmers’ costs and perhaps enhancing productivity.
A team of researchers at MIT and a spinoff company they launched has developed a system to do just that. Their technology adds a thin coating around droplets as they are being sprayed onto a field, greatly reducing their tendency to bounce off leaves and end up wasted on the ground. Instead, the coated droplets stick to the leaves as intended.
The research, published today in the journal Soft Matter, was co-authored by recent MIT alumni Vishnu Jayaprakash and Sreedath Panat, graduate student Simon Rufer and MIT professor of mechanical engineering Kripa Varanasi.
The necessity of this innovation is underscored by a recent study showing that pesticide-free farming could result in the loss of 78% of fruit, 54% of vegetable and 32% of cereal production. Currently, farmers often rely on traditional methods to apply these chemicals, leading to over-spraying and runoff, which pollutes waterways and degrades soil quality.
Pesticides take a significant toll on global health and the environment. A recent study found that 31% of agricultural soils around the world were at high risk from pesticide pollution. In the United States alone, farmers spend $16 billion annually on pesticides.
“Over more than a decade of research in my lab at MIT, we have developed fundamental understandings of spraying and the interaction between droplets and plants — studying when they bounce and all the ways we have to make them stick better and enhance coverage,” Varanasi said in a news release.
Initially, the team experimented with a two-nozzle system using electrostatically charged droplets, but the complexity and cost of retrofitting existing equipment proved impractical for farmers. Instead, they found success with a simpler, single-nozzle system that coats each droplet with a minuscule layer of oil.
High-speed cameras revealed the effectiveness of the oil coating. When untreated droplets landed on hydrophobic leaf surfaces, they spread into a pancake shape before bouncing away. By coating the droplets with less than 1% of oil, they spread out but remained adhered to the surface. This treatment increased the retention of droplets by as much as one hundredfold.
“When these droplets are hitting the surface and as they expand, they form this oil ring that essentially pins the droplet to the surface,” Rufer added.
The researchers noted that even minute quantities of oil significantly reduced droplet rebound.
In field tests, they initially used soybean oil but soon discovered that surfactants and adjuvants, chemicals already used by farmers, also worked effectively.
“That way,” added Varanasi, “we’re not introducing a new chemical or changed chemistries into their field, but they’re using things they’ve known for a long time.”
Varanasi and Jayaprakash formed the company AgZen to commercialize this technology. To validate their system’s efficacy, they developed a monitoring tool called RealCoverage, which has been deployed on farms ranging in size from a few dozen to hundreds of thousands of acres. This system has saved farmers 30% to 50% on pesticide costs by optimizing the application process.
“You could give back a billion dollars to U.S. growers if you just saved 6% of their pesticide budget,” Jayaprakash, lead author and CEO of AgZen, said in the news release. “In the lab, we got 300% more product on the plant. So that means we could achieve orders of magnitude reductions in the amount of pesticides that farmers are spraying.”
Field tests have demonstrated the practicality of the new system.
“[W]e doubled the amount of product on kale and soybeans just by changing where the adjuvant was,” Jayaprakash added. The spray system is convenient for farmers because, as Jayaprakash explained, “all they’re doing is changing their nozzle. They’re getting all their existing chemicals to work better, and they’re getting more product on the plant.”
This innovation “is useful for every chemistry that’s going on the leaf, be it an insecticide, a herbicide, a fungicide, or foliar nutrition,” Varanasi added.
The team plans to introduce the new spray system on about 30,000 acres of cropland within the year.
Varanasi emphasized the relevance of this technology given global population growth projections.
“[T]he amount of food production has got to double, and we are limited in so many resources,” he said. “This means that every acre we currently farm must become more efficient and able to do more with less.”
AgZen has recently raised $10 million in venture financing to support the commercial deployment of these technologies.
“The knowledge we are gathering from every leaf, combined with our expertise in interfacial science and fluid mechanics, is giving us unparalleled insights into how chemicals are used and developed,” Varanasi added. “Our mission is to use these technologies to deliver improved outcomes and reduced costs for the ag industry.”
By bringing this innovative technology to market, AgZen aims to revolutionize agricultural practices, making them more sustainable and efficient, while also addressing critical environmental concerns.