On most lettuce farms, workers weave between rows to cull extra heads of lettuce crowding out the healthiest plants. The practice, called thinning, is labor-intensive and a labor shortage has made it difficult to find workers for the task.

In 2011, Jorge Heraud and Lee Redden came up with the idea to use robotics to mechanize lettuce thinning as part of their coursework in Stanford's executive MBA program.

"Mention robotics in agriculture and people think it's R2D2 and C3PO going into the field, but that's not quite what we do," says Heraud, the former head of precision agriculture for GPS tech giant Trimble Navigation.

Their product, the LettuceBot, is a "smart" farm implement that attaches to a tractor. Using cameras and algorithms, the machine measures plant size and assesses color, making split-second decisions about which lettuce plants to keep.

The pair launched their Sunnyvale, Calif., startup Blue River Technology in 2011. They raised $13 million between 2012 and 2014 to bring their inaugural product to market.

The LettuceBot has put Blue River Technology at the forefront of a new trend: Entrepreneurs creating high-tech applications for agriculture.

"There are tremendous opportunities for smarter, more precise applications that can be used in the field," Heraud explains.

The "ag tech" sector has experienced rapid growth. An average of 132 new ag tech startups launched each year between 2006 and 2012, with private sector investments topping $10 billion in 2010, according to the latest research from the Kauffman Foundation.

"[VCs] like to invest in areas where new disruptive technologies can bring change in industries," Heraud says. "Ag tech fits that definition."

New VC firm AgTech Innovation is working to raise $50 million to launch a fund that invests in agricultural technology. It's one of several VC firms around the country raising capital for investments in agricultural technology and renewable energy. There's even a crowdfunding platform: AgFunder launched in 2013 to match ag tech companies with accredited investors.

Several high-profile acquisitions have excited investors, but the promise for farmers is even greater.

Dairy farmers often rely on handwritten records or simple spreadsheets to monitor animal health and manage breeding operations, according to farm kid-turned-entrepreneur Matija Kopic.

"Even the more advanced databases [available to farmers] can track simple events but have no analytics for farmers to measure the impact of their decisions," Kopic explains.

In 2011, Kopic and Marko Dukmenic launched Farmeron, a cloud-based software platform that provides real-time data on things like the impact of feed quality on production to conception rates for each animal. The Silicon Valley startup raised $4 million in seed funding.

More than 100 farmers currently use the software, which can increase their productivity and efficiency by as much as 50%. In some rural areas, it's the first time farmers have been able to use high-tech methods to track production.

"Rural connectivity is a major barrier," Kopic explains. "There has been a lag in terms of broadband penetration on farms; now that infrastructure is more widely available, it's fertile land for startups to emerge."

Kopic believes this will lead to an explosion of startups developing apps for farmers in the next decade. As more farmers embrace technology, Farmeron continues growing. Kopic expects that the software will be used to track more than one million cows on farms across the U.S. in 2015, quadrupling their current reach.

Blue River Technology is also focused on growth.

Since the LettuceBot entered the market in 2013, the company has contracted with 20 farms, including four of the largest lettuce growers in the nation. There is currently more demand for the technology than the startup can accommodate.

"Agriculture was left behind by modern technology, until now," Heraud says. "This is a new age of automation in agriculture."