Human Hair: The Next Green Fertilizer?

Jan. 15, 2009 -- Scientists are exploring an Earth-friendly way to use all that hair that piles up on salon floors -- as fertilizer.

A new study adds hair to a growing list of waste products that can boost crop growth. The list already includes cow manure, sewage sludge, and sheep wool.

"We concluded that human hair can release a sufficient amount of nutrients to support crops," said agricultural scientist Valtcho Zeliazkov of Mississippi State University in Verona. "This is a waste material with clear benefits for producers and the environment."

The idea is not entirely new. In fact, hair-based fertilizer is already commercially available. A Florida-based company called SmartGrow, for one, sells hair-containing mats that gardeners place beneath or on top of their plants. The company claims the mats add nutrients, hold in moisture, and battle weeds, while making chemicals unnecessary. Its Web site showcases a series of photographs depicting lush, healthy plants grown with the product and wimpy, wilted ones grown without it.

Zeliazkov wanted to see whether it really worked. He and colleagues began by growing 48 lettuce seeds and 48 wormwood seeds in individual pots in a greenhouse. Into the soil of each pot, the scientists added either a quarter-sized cube of hair waste (in varying concentrations), a controlled-release fertilizer, a water-soluble fertilizer, or no treatment at all.

With hair treatments, results showed, the plants grew better than with no treatments at all. But chemical fertilizers did best. Results from the second half of the experiment were more promising. This time, the researchers planted the medicinal herb feverfew in the pots that had originally grown lettuce and yellow poppy seeds in the pots that had held wormwood. They otherwise left the soil alone.

Twenty weeks later, the poppies had grown best in pots that contained hair cubes with 5 or 10 percent hair by weight. For feverfew, yields were equally high in hair-treated and chemically treated pots. Results appeared recently in the journal HortTechnology.

Hair contains all the organic nutrients that plants need to grow, Zeliazkov said. But it takes about a month for those nutrients to break down into an inorganic form that plants can use. That's why the second round of hair-treated plants grew better than the first.

Those results suggest that hair could be a good fertilizer for slow-growing crops, such as basil, sage, and ornamental shrubs, Zeliazkov said. For quicker-growing vegetables, gardeners might need to mix hair with chemicals to get through the first few weeks. Hair is on the list of certified organic growing methods.

On a small scale, hair might be a useful addition to the gardener's toolbox, said Allen Barker, a plant and soil scientist at the University of Massachusetts in Amherst. "But I don't think it's going to replace other sources of fertilizer," he added. "There's not enough hair around to amount to anything."

Using hair to grow fruits and vegetables also brings up both health issues and ethical concerns. Zeliazkov has found traces of lead in some hair samples, for one thing. SmartGrow gets most of its hair from India and China, he added.