The clumps of discarded hair on the barbershop floor could one day help sustainability efforts by growing salad out of human hair, thanks to scientists from Nanyang Technological University, Singapore (NTU Singapore), who have created the growth medium used in urban farming – known as hydroponics substrates – using keratin extracted from human hair.
In hydroponics, crops are grown without soil, using a substrate that acts as both a support structure and a reservoir for water and nutrients. The keratin-based substrates developed by the NTU research team have been tested with crops such as microgreens and leafy vegetables, including the Chinese cabbage bok choy and arugula leaves, also known as rocket.
In their study, the NTU researchers first extracted keratin from human hair gathered from hair salons and barbershops. The keratin solution is mixed with cellulose fibres to strengthen it, which is then dried into a spongy substrate.
The substrate is sustainable, biodegradable, and eco-friendly as it is made from waste material and becomes a source of nutrients for the plants as it degrades. The yield from this keratin-based substrate is comparable to materials currently available on the market, according to laboratory tests. Professor Ng Kee Woei, Associate Chair (Research) at NTU’s School of Materials Science and Engineering (MSE), who led the research, said: “Besides hair, livestock farming produces large amounts of keratin as biowastes, as it is found abundantly in wool, horns, hooves, and feathers. Since keratin can be extracted from many types of farm wastes, developing keratin-based hydroponic substrates could be an important strategy for recycling farm wastes as part of sustainable agriculture.”
The researchers hope their substrate offers a renewable alternative to current commercial offerings, such as those made from rockwool, polyurethane and phenolic foams which are not sustainable and do not provide nutrition to plants.
Hair Today, Crop Tomorrow
Keratin is composed of amino acids that are a source of nutrients for plant growth. These amino acids can also bind other types of nutrients and release them under controlled conditions. Keratin therefore has great potential as a growth medium used in hydroponics and urban agriculture, where the timely release of nutrients and water is essential.
However, keratin is not strong enough by itself to form a substrate. The researchers mixed it with cellulose fibres to strengthen its structure and improve its water-swelling capabilities. The cellulose was extracted from softwood pulp, meaning the final product is sustainable. Prof Ng said: “Our keratin-based substrate can hold water up to 40 times its original weight, which is on par with commercial substrates currently available.” A gram of human hair can produce about three blocks of substrates of about 1.5cm by 1.5cm by 3cm, or the size of a small ice cube. “The plants actually grew much longer root systems in the keratin-based substrates, which is a promising sign that vegetable roots can better penetrate keratin-based substrates and more effectively absorb nutrients released from the substrates,” said Prof Ng.
In its current form, the keratin substrate developed by the research team can last between four to eight weeks, depending on conditions. It also leaves no waste behind, unlike commercial substrates currently available in the market that do not degrade and become solid waste after harvest.