On a farm in Australia this winter, cows ambled across open fields, munching precisely on the grass that was ready for grazing and avoiding the areas that needed to recover and regrow. There were no fences to guide them. And these weren't especially smart cows. This was the work of a smartphone app.

Vence is a San Diego-based startup that wants to bring farming into the 21st century. The company makes a device and accompanying software that lets farmers control their animals' behavior remotely. Launching in April, it could have huge implications for agriculture--and the planet.

When left alone, livestock will often cluster in certain areas of a field while leaving other regions alone. That causes some sections to be overeaten, which makes the grass and soil there less healthy over time. The neglected areas--left to overgrow and develop weeds, and without the benefits of being fertilized--also suffer. And unhealthy grass hurts a farmer's bottom line.

For decades, farmers have combated this problem using a method called rotational grazing. Generally, that entails building several fenced-in paddocks between which they can alternate their livestock, giving the grass in each area time to grow back before it's eaten again.

Vence founder and CEO Frank Wooten, a former New York-based investment banker, doesn't have a background in agriculture. What he apparently does have: an open mind. In 2016, he was working as a startup consultant in Brazil when a friend who owned farms presented him with a business idea: What if farmers could achieve rotational grazing for much cheaper using Pavlovian training?

Wooten's curiosity was piqued. Over the next seven months, he traveled around the world interviewing farmers. "Every person that I spoke with--regardless of country, age, size of farm, or type of animal that they were managing--hated fencing," he says. The complaints: cost, labor to build them, time spent on maintenance. "It was a really well-defined pain point."

Wooten studied research on Pavlovian training performed by MIT and the U.S. Department of Agriculture. He reached a promising conclusion: The tech required to produce a solution was already viable, but no one had yet attempted to deploy it at scale. The entrepreneur raised a few hundred thousand dollars from friends and family, brought on several experts as advisers in exchange for equity, and got to work building an electric collar. 

Today, Vence makes a collar that can be placed on animals like cattle, sheep, goats, and bison. It contains GPS and a magnetometer that detects which way an animal is facing. If the animal strolls somewhere it shouldn't, the collar emits a buzzing noise. If it goes further, it gets shocked. "They get trained pretty quickly to respect that," Wooten says. When it's time for the herd to move to a new area, the buzzing starts again and stops when the animals walk in the right direction.

Farmers have the option of creating their own rotational schedule or letting Vence's series of algorithms do the work. The entire system, which also monitors the animals' vitals, can be controlled from a phone, tablet, or other device. The startup will charge between $15 and $25 per collar annually, depending on the amount of livestock.

The effects of Vence's technology could extend beyond agriculture. One acre of grass absorbs up to three tons of carbon each year. When it's dead or unhealthy, though, it loses much or all of that ability. With improved grazing techniques, estimates global warming think tank Project Drawdown, the world could sequester an additional 16.3 gigatons of carbon--nearly three years' worth of total U.S. emissions--over the next 30 years.

Combine that with the fact that there are more than 3 billion grass-grazing livestock on the world's farms, and it could mean a whole lot of interest in Vence's product.

Of course, the system is sure to have its detractors. Animal lovers won't be keen on the idea of shocking animals to control their movements. On its website, PETA points out that when used on dogs, shock collars can cause "psychological stress, including severe anxiety." 

And the startup may have a tough slog wrestling its way into an industry largely based on centuries-old methods. While invisible electric fencing has been around for some time, the agriculture world has largely steered clear. Keith Johnson, professor of agronomy at Purdue University in Indiana, says he doesn't know of any farms in the state that use it. 

There's also the fear of allowing an algorithm to control a process that farmers are trained to do by eye. "It better have a small standard deviation," Johnson says. "One or two extra days of grazing can do some damage."

Still, if the concept can help make farms more profitable, Johnson says farmers will be for it. "As an industry, we always have to be looking forward," he says. "Like any approach, I think it needs to be evaluated carefully."

For its part, Vence has performed pilot tests in Australia that Wooten says have been successful. The startup has has pulled in a total of $5.5 million in funding from firms including Utah-based Kickstart Capital and Rabobank, a Dutch financial company that invests heavily in agriculture.

The tech officially rolls out to the public on April 15. Wooten says the company already has a waitlist of hundreds of farms hoping to participate in pilot programs, plus a backlog of pre-orders for tens of thousands of units.

"We think that this is part of the climate solution, and we also think it's part of the food solution," Wooten says. "We want to be the livestock manager of the world."