Farm Waste Fashionistas
In the near future, when you reach for your favorite shirt or sweater – textile scientist Yiqi Yang wants you to thank CORN – not cotton – for that soft, comfortable feel.
Yang thinks part of the world’s most abundant grain may one day rival cotton as the future of textiles.
Yang develops sustainable bio-based textile fibers as a biochemical engineer at the University of Nebraska’s Department of Textiles, Merchandising and Fashion Design. “All clothing is created from fibers,” says Yang. Some are natural, from plants and animals, like cotton, linen, and wool. Others are manufactured from oil-based synthetics, including polyester, spandex, and nylon. The clothing we wear is determined by the supply and demand of natural and synthetic fibers.
A radical change in global fibers
For more than 50 years, a radical shift has been taking place in the worldwide source of fibers. In the 1960s, 80% of fibers were natural, while 20% were oil-based synthetics. Today, synthetics dominate the market because petro-based fibers have been cheap and durable, while natural fibers require higher investments in land and water to grow.
But our changing world is impacting the textile supply. An oil shortage is causing petroleum prices to rise, increasing the cost of synthetics. And soaring global populations are competing for space traditionally used to grow crops and cotton – creating a critical need to both feed and clothe the spiraling masses with less available land. Yang fears a crisis is brewing that could create an uncertain future – one that pits growing food vs. clothing fibers.
Right now, the world’s annual demand for textile fibers is 85 million tons. Just 15 years ago, it was about half that figure. Yang cautions, “The consumption will double again in the next 10-15 years. So everyone in the fiber industry worries how we can get that much fiber for the unlimited demands of humankind?”
Corn tops Yang’s list of new fiber options. “If you look at history, textiles are agriculture. And Nebraska is the place we have lots of corn,” says Yang. Corn is also grown worldwide. Most of that crop is used to feed people and animals – with some serving as a fuel additive.
But it’s not the corn kernels that interest Yang. It’s their husks he’s after – part of the farm waste left behind in the harvesting process.
Can farm waste become fiber?
Worldwide, the annual farm waste from corn is enormous, a whopping 400 million tons. That’s enough to fill 1,000 Superdomes each year! The stalks, leaves and husks are normally diced up during harvesting and left on the fields to decompose as fertilizer to enrich the soil for the next growing season. But where farmers see fodder for soil, Yang sees a new source of renewable natural fibers that could reduce our dependence on oil-based synthetics – and help meet the world’s textile needs.
So, how can Yang’s corn husks become textiles? Corn husks, like cotton, contains cellulose, the building blocks of plant’s cell walls. Cotton is almost pure cellulose that is plucked from the plant’s flower. But corn husks, stalks, cobs, and leaves are made of lignocellulose – complex and woody biopolymers (lignen, cellulose, and hemicellulose) that are distributed throughout the plant. Many of the fibers in the stalks and leaves are too coarse for textiles. But finer fibers are embedded in the husks to protect the kernels throughout a long growing season. To make husks useful for textiles, Yang and his researchers separate the lignocellulose fibers from the husks in a patented biochemical process.
Converting husks to fibers in the lab
Yang’s team designed a custom-built test lab for the process. “We use common, non-toxic chemicals in a mechanical and biochemical process to extract the fibers,” he says. Yang’s graduate students empty a trash can of husks into a stainless steel tumbling reactor and add a solution of simple chemicals (acetic acid, sodium chloride, sodium hydroxide, surfactants, and softeners). Piping in hot water, the reactor rotates continuously for half an hour as the solution breaks down the rigid husk material, leaving behind clumps of coarse fibers. The fibers are then washed with water, and dried. Finally, another biochemical treatment reduces the diameter of the coarse fibers to make finer strands. Once the fine fibers are bleached, they can be spun into yarns and colored with common cotton dyes.
Although the husk fibers look similar to common textile fibers, Yang says they have different properties than cotton or linen. “Fibers from corn husks have much better stretchability compared to any other natural cellulose fibers. That makes it compatible to be spun together with synthetic fibers, like polyester, that are usually mixed with cotton in making textiles,” he explains.
The lab has proved that husk fibers can be made on a small scale. So far, Yang’s team has made one prototype, a red sweater from a yarn mixed from corn husks and polyester fibers. By touch, it’s softer than linen, but similar to cotton. But making one sweater requires a single trash can of husks.
Can corn husks find a market?
To get the process to work on an industrial scale will require massive volumes of husks. That’s no easy task. “Right now, it’s a challenge because there’s not a market for husks,” laments Yang. For the most part, the farming industry is set up to harvest corn for its kernels. Conventional harvesters shell the corn grain, but aren’t designed to separate the rest of the corn plant.
Consulting industry experts, Yang found two exceptions – seed corn and sweet corn manufacturers. Both harvest full cobs, complete with husks. A&K Development Company in Eugene, Oregon manufactures high-speed automated corn husking assemblies that shred the husks off in the blink of an eye before shelling the kernels for seed or sweet corn. Most of these husks are sold to livestock breeders as feed for cattle. In time, these growers and manufacturers might become a source for husks. But it would take complex distribution to make it work – and transportation costs might make it unaffordable.
For a while, it looked like the Yang might have to rely upon a century old solution – picking husks by hand. To help, the University of Nebraska-Lincoln enlisted the help of 4-H, the nation’s youth agricultural organization. Thomas Dux, Mead High School science teacher and 4-H leader, organized a class project to help Yang by having his students collect husks in trash bags. “Someday, we hope corn husks will be a commodity,” says Dux, as he bags a fistful of husks.
But collecting husks by hand is impractical. A single barrel weighs under 10 pounds. Yang’s team needs 1,000 pounds to run a larger scale test to convince farmers, implement manufacturers and textile mill operators that husks are worth harvesting on an industrial scale.
Dux hopes his class project inspires students to think about sustainable agriculture and new uses for crops. “Maybe one of our students will be the person who creates a part of a combine that actually separates the husk and stores them in a bin,” he adds hopefully.
Unbeknownst to the class, 40 miles away, two enterprising twins, Ty and Jay Stukenholtz, are closing in on a solution. The Stukenholz brothers are agricultural engineers who farm near Nebraska City. During the past 10 years, they’ve designed and custom-built three combines and formed a company, FarmMax, to create sustainable harvesting equipment. They began with a prototype harvester that separates cobs as a source for biochemicals and biofuels. “Over the years, we figured ways to clean the waste stream from a combine,” says Ty Stukenholtz.
When the Stukenholtz brothers learned of Yang’s plan to harvest husks for textile fibers, they re-designed their harvester to separate kernels and cobs, grind the stalks as mulch for the field, and eject the husks out the back of the combine to collect in a bobcat. “There is literally no combine in the world that can do what this machine is doing right now,” adds Ty.
Since then, they’ve re-engineered a farm waste recovery device that attaches onto existing commercial combines. Jay adds, “We’ve designed it to fit any combine.” Soon, their invention will allow farmers to collect kernels, cobs, and husks in one pass, while unloading them “on-the-go,” rather than pulling a cart or making multiple passes to pick up discarded farm waste. Their single-pass system is a sustainable means of saving time and fuel, while enabling farmers to create additional revenue from corn byproducts. “I think it’s got great potential,” adds Ty. “If harvesting husks brings in a similar price to cotton, farmers would really think about the value of those husks.”
The Stukenholtz farm waste recovery system may be a game changer for creating a commodity of husks. And although the market doesn’t yet exist, Yiqi Yang remains optimistic. “We have a strong agricultural industry. We’re using Ag wastes. It’s a perfect fit here in Nebraska, and there’s no reason we cannot develop a fiber industry right here at home,” said Yang.