17 May 2023

Created by researchers at Carnegie Mellon University, seed delivery devices pave the way for soil regeneration. But some observers are skeptical

by Matteo Cavallito


The distribution of seeds in the soil can be done by air through the use of drones and appropriate man-made carriers, according to researchers at Carnegie Mellon University in Pittsburgh, Pennsylvania, who, in recent months, came up with a solution called E-seed, a “bio-inspired” device designed on the model of cycutaria (Erodium) seeds.

The seeds, a statement from the U.S. university points out, sit inside a thin stem wrapped around itself. “During rain or high humidity, the corkscrew-like stalk unwinds and twists the seed into the soil, where it can take root and is safe from hungry birds and harsh environmental conditions.”

The seeds carrier

Made from a thin layer of white oak, the seed vector developed by scientists works in the same way. Unlike its natural counterpart, however, the stalk has not one but three tails, which together help maintain its vertical position in the soil. According to the researchers, the vectors – whose transport is entrusted to drones – can also be used to distribute fertilizer, fungi and nematodes.

That is, those tiny invertebrates that feed on microorganisms by taking up excess nutrients from them, which are then released into the soil to benefit plants.

“Seed burial has been heavily studied for decades in terms of mechanics, physics and materials science, but until now, no one has created an engineering equivalent,”” said Lining Yao, professor at Carnegie Mellon University. “The seed carrier research has been particularly rewarding because of its potential social impact.”

The goal: regenerate the soil

Through aerial planting, scientists explain, it is possible to solve some problems typically associated with traditional distribution. Using drones, for example, large and physically inaccessible areas can be covered quickly, improving soil quality and contributing to the regeneration of areas affected by wildfires. The use of self-perforating vectors, that is, those capable of autonomously penetrating deep into the soil, also allows seeds to be protected from the weather and the action of external factors.

“Our three-tailed carrier has an 80% drilling success rate on flat land after two triggering cycles, due to the beneficial resting angle (25°–30°) of its tail anchoring,” researchers say in an article published in the journal Nature.

Moreover, they say, “Our carriers can carry payloads of various sizes and contents including biofertilizers and plant seeds as large as those of whitebark pine, which are about 11 mm in length and about 72 mg.” The system developed, the researchers say, will improve the effectiveness of aerial seeding in alleviating agricultural and environmental stresses by paving the way for further applications in the energy sector and robotics.

Other researchers are skeptical

Not everyone, however, seems to share the same enthusiasm. In an article published by the Australian network The Conversation, some researchers pointed out the limitations that would still characterize this type of solution. “Numerous private companies have entered the market with revolutionary devices (mostly drones), claiming to restore ecosystems by planting billions of trees,” the authors write. “Yet, to date, there is little evidence of their efficacy.”

Two problems, in particular, were noted. First, it seems difficult for the moment to secure such a large production of vectors to carry the “many billions of seeds across thousands of species we need to restore entire ecosystems.”

In addition, they say, there is a logistical hurdle. To keep the queues from tangling, the researchers divided the box carried by each drone into individual compartments containing only one carrier. Thus reducing the number of seeds that can be delivered during each flight.