Electronic Soil for Alternative Farming

The World population is increasing, and we also have climate change. So 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. Research group has now developed an electrically conductive cultivation substrate, tailored to hydroponic cultivation, that they call e-Soil. Hydroponic cultivation means that plants grow without soil, needing only water, nutrients and something their roots can attach to—a substrate. It is a closed system that enables water recirculation so that each seedling gets exactly the nutrients it needs. Therefore, very little water is required and all nutrients remain in the system, which is not possible in traditional cultivation.
Hydroponics also enables vertical cultivation in large towers to maximize space efficiency. Crops already being cultivated in this manner include lettuce, herbs and some vegetables. Grains are not typically grown in hydroponics apart for their use as fodder. The researcher’s show that barley seedlings can be cultivated using hydroponics and that they have a better growth rate, thanks to electrical stimulation. “In this way, we can get seedlings to grow faster with fewer resources. We don’t yet know how it actually works, which biological mechanisms that 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.”
Mineral wool is often used as cultivation substrate in hydroponics. Not only is this non-biodegradable, it is also produced with a very energy-intensive process. The electronic cultivation substrate e-Soil is made of cellulose, the most abundant biopolymer, mixed with a conductive polymer called PEDOT. While this mixture is not novel, its application in plant cultivation and as an interface for plants is unprecedented. This combination as such is not new, but this is the first time it has been used for plant cultivation and for creating an interface for plants in this manner. Previous research has used high voltage to stimulate the roots. Eleni Stavrinidou, associate professor at the Laboratory of Organic Electronics and leader of the Electronic Plants group at Linkoping University, emphasises the urgency of finding new agricultural methods due to the increasing world population and the challenges posed by climate change. The advantage of the Linköping researchers’ “soil” is that it has very low energy consumption and no high voltage danger. 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,” In a new study published in the journal PNAS, researchers from Linkoping University have unveiled an innovative electrically conductive cultivation soil, dubbed e-Soil, which has demonstrated a remarkable ability to enhance the growth of barley seedlings by 50% within just 15 days. This development in hydroponic technology could potentially revolutionise urban farming and contribute significantly to global food security.
One of the key benefits of e-Soil is its low energy consumption and the elimination of high voltage risks associated with previous research that used high voltage to stimulate plant roots. The researchers have observed that barley seedlings grown in e-Soil process nitrogen more effectively, although the exact biological mechanisms behind the enhanced growth and electrical stimulation’s role remain to be fully understood. Stavrinidou acknowledges that while hydroponics alone may not solve the problem of food security, it can make a substantial difference, especially in regions with limited arable land and harsh environmental conditions. The study’s findings pave the way for further research into hydroponic cultivation, potentially leading to more efficient food production methods.
Researchers from Linköping University in Sweden developed a ‘bioelectronics hydroponic soil’ that can speed up the growth of plants in  hydroponic space, or farms that grow plants without soil in environments made up of mostly water and a place for roots to attach. After integrating the engineered ‘e-Soil’ into the framework where seedlings grow, researchers discovered that sending electrical signals through the soil made plants grow 50 percent more on average. Eleni Stavrinidou, the supervisor of the study, told Engadget that the soil’s conductivity was necessary for stimulating the plant roots. In this particular study, the researchers examined the effect of sending signals to barley seedlings over the span of 15 days before harvesting them for analysis. Applying a voltage as small as 0.5V on the e-Soil electrically stimulates the roots, Stavrinidou explained. This, in turn, resulted in a recordable increase in the biomass of the electrically stimulated plants when compared to the non-stimulated seedlings.
The stimulation’s effect on the barley seedlings was described as steady and transient”. Stavrinidou told Engadget that nitrogen, one of the main nutrients involved in plant growth, was processed more efficiently through the stimulation. “We found that the stimulated plants could process the nutrients more efficiently however we don’t understand how the stimulation is affecting this process,” Stavrindou explained, adding that the reason behind the growth process will be a focus of future studies. While hydroponic techniques are mainly used to grow leafy greens and some vegetables like cucumbers and tomatoes, the e-Soil could offer a solution to create new ways to increase crop yields in commercial settings and especially in places where environmental conditions impact plant growth. The study highlights that this technique could minimize the use of fertilizers in farming.
But beyond improving crop yield, the implementation of e-Soil in hydroponic farms could make them more energy-conscious. While traditional hydroponic farms use up less water, they require more energy to run. “The e-Soil consumes very little power in the microwatt range,” Stavrinidou said. Before this technology can be applied to large scale agriculture and other types of crops, more studies need to be conducted to observe how electrical stimulation can impact the whole growth cycle of a plant throughout its entire lifespan and not just in the early stages of seedling maturation. Stavrinidou also said that her team plans on studying how the technique affects the growth of other plant species.
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