In the face of growing obstacles in the quest for food security, a promising study from Linköping University offers hope. The study presents a novel method of soilless gardening, or hydroponics, using an electrically conductive growing medium called "electronic soil" or eSoil. The Electronic Plants group, led by Eleni Stavrinidou, an associate professor in the Laboratory of Organic Electronics, has made significant advances in hydroponic technology with its groundbreaking work. From what it is to how it works, let's explore the extensive details of eSoil and its potential impact.

What is eSoil?

According to the study, in hydroponic environments, eSoil is a low-power bioelectronic growth substrate that can electrically stimulate the root system and growth environment of plants. This novel substrate is not only environmentally friendly, being derived from cellulose and a conductive polymer called PEDOT, but also offers a low energy, safe alternative to previous methods that required high voltage and non-biodegradable materials. eSoil uses low energy and minimises resource consumption. Its active material is an organic mixed-ionic electronic conductor.

How does eSoil work?

The study's findings represent a noteworthy advancement. When the roots of barley seedlings were electrically stimulated for 15 days, they showed a 50% increase in growth using eSoil. This research promotes more effective and sustainable development while increasing the variety of crops that can be grown hydroponically. In hydroponics, plants are grown without soil, requiring only water, nutrients and a substrate - something for their roots to attach to. This closed system allows water to be recirculated, ensuring that each seedling receives exactly the nutrients it needs. As a result, very little water is used and all the nutrients remain in the system - something that is not possible with conventional farming.

To maximise the use of space, hydroponics also allows vertical production in huge towers. Crops currently grown in this way include lettuce, herbs and some vegetables. Hydroponics is not usually used to grow grains other than animal feed. In this paper, the scientists show that barley seedlings can be grown hydroponically and that electrical stimulation improves the plants' growth rate. “In this way, we can get seedlings to grow faster with fewer resources. We don’t yet know how it actually works, and which biological mechanisms are involved. What we have found is that seedlings process nitrogen more effectively, but it’s not clear yet how the electrical stimulation impacts this process,” says Eleni Starvrinidou.

What are the benefits of using eSoil?

Linköping University's research represents a major step forward in urban agriculture. Combined with the advantages of hydroponics, such as the ability of vertical farming to utilise available space, eSoil's low energy consumption and safety features offer a sustainable answer to the world's growing food needs. Highlighting the current global challenges of a burgeoning population and climate change, Professor Eleni Stavrinidou, said “It’s clear that we won’t be able to cover the food demands of the planet with only the already existing agricultural methods. But with hydroponics, we can grow food also in urban environments in very controlled settings."

Eleni Stavrinidou believes that the new study will open the pathway for new research areas to develop further hydroponic cultivation. “We can’t say that hydroponics will solve the problem of food security. But it can definitely help particularly in areas with little arable land and with harsh environmental conditions,” she added. In conclusion, this research illuminates the possibilities of hydroponics in urban environments and simultaneously provides impetus for additional exploration and advancements in sustainable agriculture.

The full study was published in the journal PNAS.