When the soil is electrified, barley grows faster

Barley also grows by half as much if you add a very small amount of electricity to the soil. Researchers from Linköping University in Sweden discovered this during experiments conducted on small plants on artificial soil. They believe their “electronic soils”, or eSoils, could help feed the world's growing population, especially in arid or infertile regions. search Published last week in With people.

Growing plants without natural soil, but only in water containing dissolved nutrients, has been practiced since the 17th century. “Hydroponics,” or water farming, has taken off in recent decades. For example, companies are already growing spinach, lettuce, tomatoes, flowers and all kinds of herbs on a large scale in enclosed spaces, often in vertical racks and under LED lighting.

The LED light can burn for 24 hours

This vertical farming holds great promise for the global food supply. Hydroponics is more efficient than conventional farming. Firstly in terms of space requirements: since you rise higher, this farming is also suitable in cities. Then there is water consumption. To grow one kilogram of tomatoes, you need about 17 liters of water in a Dutch greenhouse, and in a field in southern Europe easily 60 to 200 litres. calculated Wageningen University. In a growing apartment 2 to 4 liters will work. You can leave the LED light on for 24 hours. 100% of the nutrients in the circulating growing medium end up in the crop, while much of it leaches out on the ground and the plants absorb only 50% of the nutrients from the field anyway, according to the Swedish researchers. Finally, in a closed environment you do not need any pesticides.

Sometimes the roots of plants in hydroponics dangle in the water; Sometimes they grow in a matrix, for example in clay pellets, coconut fibers or rockwool. In their study, the Swedes used a porous polymer, made mainly of cellulose: the natural material from which plants derive their strength. But they also added the synthetic polymer PEDOT:PSS (for fans: poly(3,4-ethylenedioxythiophene):polystyrene sulfonate). This increases electrical conductivity.

Electronic bottoms require very little electrical current

The Swedes showed for the first time that barley plants grow on this matrix just as they grow on a conventional rockwool matrix. They then investigated, in different systems, what happened when they slightly electrified the soil (0.5 volts) for five days. Electrical stimulation increased biomass by 50% on day 15. Strikingly, additional growth did not occur during stimulation, but only in the following days.

The Swedes were interested in knowing why plants grow better in e-soil. The first hypothesis was that negatively charged nitrate ions in the nutrient medium could be better transported to plant roots thanks to the electric field.

At the molecular level

It turned out not to be the case: in the control soil, the roots absorbed as much nitrate as in the E-soil. The difference seems to occur only in the plant itself, when it converts nitrates into organic nitrogen compounds (such as proteins). But the Swedes want to further investigate how exactly this works at the molecular level. They also want to know whether the chemical and physical composition of the soil can ensure better plant growth.

Hydroponics is a realistic option for widespread application, as the Swedes emphasize in the conclusion of their article. The soil is easy to make, cheap and environmentally friendly – ​​especially compared to rockwool, which requires a lot of energy to produce. E-soil also requires very little electrical power, which can be easily supplied by everyday rechargeable batteries. The system also appears to be suitable for growing cereal crops, such as barley, which is widely used for animal feed. The Swedes want to know what other crops their method also offers advantages, and which electrical system is best.

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