But if the whole plant is buried, then harvesters don’t know where to cut the tasty shoot from the rest of the plant. If they cut too high, the shoots may not be long enough to sell. If they cut too low, they risk trimming into the roots and killing the whole plant, which could otherwise live and produce shoots for as long as a decade.
So scientists from the Braunschweig University of Technology did what anyone in the same predicament would do: They strapped a ground-penetrating radar (GPR) detector to a little cart, pointed the detector at the mound of buried asparagus plants, and used the results to find the perfect asparagus cutting height. They published their research in the Journal of Applied Geophysics last month.
Study co-authors Jörg Schöbel and Daniel Seyfried wanted to find agricultural problems with scientific solutions, and white asparagus was a perfect fit. “We immediately recognized it as a well-suited application for GPR,” they said in an email.
GPR is normally used to look for buried things such as land mines or pipes and cables. It works by emitting radio waves in a wall perpendicular to the mound. It's sort of like sending a wall of tiny dogs into a forest to fetch tennis balls, then measuring how long it takes the dogs to come back (but slightly less ridiculous).
Since asparagus is mostly water and dirt is mostly dirt, the radio waves bounce back at different times – the quicker a single dog returns with the ball, the closer his or her ball was. Additionally, if we strapped a little speedometer to each pup, we'd know that those who ran the fastest must have run through the part of the forest with the fewest trees. In this scenario, the trees are the asparagus.
But there’s a catch – clutter in the ground itself can muddy up the radargram, or the log of which dogs returned when and where. Some of the dogs can't pass through thicker parts of the forest and come back without a ball. As the radar emitter moves forward along the mound, the scientists get the full radargram of all these dogs, both the successful and unsuccessful ones, and then must use sophisticated processing techniques to figure out where the asparagus is.
From there, it was simple to determine an optimal cutting height. Woof.
We wouldn't and couldn't use GPR on our familiar green asparagus, since the shoots aren’t buried. But there might be a use for similar technology, even in the United States.
Right now, farmers have no automated way of cutting asparagus at variable heights. Asparagus shoots can grow incredibly fast – sometimes as much as two inches on a hot day, said Michael Orzolek, professor emeritus of vegetable crops at Penn State. Shoot heights can be so different that setting one level to cut everything often wastes a lot of the shorter shoots, but harvesting the crops by hand takes too much time. Orzolek thinks that if a radar detector could be attached to a harvester – allowing the machine to smartly harvest different shoots at different heights in real time – it would save farmers a lot of money in wasted asparagus.
“With asparagus we're looking for a selective harvesting that would be able to pick an 8- to 10-inch spear and leave the rest alone," Orzolek said. “It's a very difficult crop to harvest.”
It will be a long while before Schöbel and Seyfried’s radar detection method is ready for the German asparagus industry, and it could cost tens of thousands of euros to implement. However, the money saved from waste reduction might make the investment worthwhile for some companies.
Schöbel and Seyfried were most excited about coming up with such a novel application for radar detection, saying, “From a scientific point of view, our research shows that two different disciplines, agriculture and high-frequency technology, may benefit greatly from each other.”