Credit: Elizabeth Intac

They say necessity is the mother of invention, but for Adnan Sharif a dose of forgetfulness was the catalyst.

Sharif is a chemical engineering master’s student at the University of Toronto. His invention is a 3D printed soil for hydroponic farming – one that’s more environmentally friendly than traditional hydroponic soil.

It’s an innovation rooted in his experience working in a plant pathology lab. “Being an undergrad, I was quite unreliable and I would forget to water the plants,” says Sharif. “My subjects kept dying.”

He figured the key to longer stretches between watering might lie in growing plants in engineered soil, just like commercial hydroponic operations. So he brainstormed solutions with his father, a mechanical and electrical engineering professor in Japan with expertise in manufacturing complex materials with porous three-dimensional structures.

What they ended up with was hydroponic soil printed using biopolymers such as corn-based polylactic acid. The soil retains just enough water to keep the plants alive for about a week.

Engineering sustainability

But better water retention wasn’t their only aim. They also wanted to help reduce the industry’s carbon footprint.

Traditional hydroponic soil is made of something the construction industry calls rockwool insulation. It’s a rock-based mineral fibre insulation made of volcanic basalt rock and recycled slag – a by-product of the steel industry. But add a hydrophilic coating to rockwool and you’ve got a soil substitute.

“The stuff you see in your walls as insulation is exactly the same thing, except they put a hydrophobic coating on it so your walls don’t get soggy,” says Sharif.

The problem is that rockwool is not the most environmentally friendly product. The rock used to make it is generally mined far away from most greenhouse operations and must be transported great distances. The manufacturing process requires high temperatures, and because rockwool is very spongy, roots get so entangled that they are hard to separate out in order to recycle the hydroponic soil.

“There are recycling centres, but they’re not widely used,” says Sharif. “It (hydroponic soil) usually ends up in the landfill.”

Sharif and his father took a different approach. “Instead of a block-like structure like rockwool cubes where the roots get entangled within the soil substrate, we engineered individual biopolymer pellets with a certain kind of porosity to resemble the sand, silt, and clay of real soil such that it holds just the right amount of water.”

This means it can be cleaned and reused for up to a couple years, depending on the kind of biopolymer used. After that, it can be composted.

Plus, polylactic acid from corn can be sourced locally and doesn’t require high temperatures to turn it into a hydroponic soil replacement. Sharif estimates their manufacturing and recycling process is up to 65 times less carbon intensive than rockwool.

A business blooms

Soon after proving he could manufacture the soil, Sharif turned to some friends to consider how to turn the invention into a business. Today, they call it SmartSoil and it’s the basis of Lyrata, a startup he helped found that grows crops for caterers and high-end restaurants in the Toronto region. The company grows more than 15 different types of crops, including basil, parsley, and mizuna, a type of Japanese mustard greens.

Lyrata also builds modular hydroponic units about the size of a single parking space containing lights, SmartSoil and an irrigation system.

“Our clients sign a contract with us to place a unit on their site, and we take care of everything from planting to harvesting,” Lyrata co-founder and engineering graduate Leo Hua told University of Toronto Engineering News. “For a flat fee, they get a self-contained farm that provides a reliable quantity of their desired crop over a set period of time.”