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Agricultural Horizons - Agricultural Sustainability Notes Series    





Rising lumber prices, decreasing supplies and environmental concerns are all cited as reasons straw-based building products are in demand. Straw is a renewable resource capable of relieving pressure on timber. Trees are harvested for wood but barley and wheat for grain. Straw is a by-product. But an ever-increasing population nevertheless demands more wood. This inevitably leads to regional wood shortages manifested in a general rise in wood costs. Straw as a new fiber source can substitute for wood, thereby preserving forests.

As new companies start up to meet this demand, farmers in some areas have a market for their straw. Some in the building industry see straw as a viable and near perfect alternative to wood: it is abundant, renewable and inexpensive. North American farmers produce an estimated 150 million tons of straw each year as a by-product of the continent's massive cereal grain harvest. Many growers would love to have a market for straw because it can be a disposal problem. The raw material is obviously there, but the ultimate success of the new industry will depend on the performance of the strawboard itself.

So, how does it do as a building product? It is durable, a good insulator and resists moisture and rot. Straw's greatest potential as a building material today seems to be as "strawboard"-straw pressed under intense heat and pressure to create a fiberboard. Naturally occurring resins in the straw, under pressure, bond it into a hard wood-like material. The resulting straw fiberboard (or particleboard) is used as floor underlay, cabinets, trim, siding, furniture and structural insulating panels. A house made using structural fiberboard panels requires 85 percent less timber than a conventional wood-frame home.

If the new straw building industry eventually uses just 25 percent of the known available supply of straw, about 37.5 million tons, it would be enough to provide structural panels (exterior wall, roof, interior partitions and floors) for one million two-story houses every year. According to industry spokesmen, that's nearly 2.2 billion square meters of straw particleboard. The projected figure is four times the current total of the U.S. production.

Particleboard is in common use in all types of building construction: wall and floor panels, doors, furniture and cabinetry. Wheat straw particleboard is made from wheat straw, a waste product from wheat farming bound together with resin. Bales of wheat straw are milled into fine particles, sorted and dried, and then bound together with a formaldehyde-free resin. The particles are then hot-pressed into sheets of the desired thickness. The sheet is sanded and cut to required sizes.

One of the primary advantages of this product is that the resin which binds the straw fibers together is formaldehyde-free, and is thus free of harmful emissions, both in use and in manufacture. The main ingredient-wheat straw-is a low-cost waste product; its use provides a second income to farmers and it is readily available and accessible.

Environmental Benefits of Straw Removal

  • Removal of straw
    • increases soil temperature in spring,
    • reduces soil dryout in summer,
    • helpful to low-till or no-till farming,
    • decreases combine operating costs,
    • diminishes risk of disease and insect transfer to next season.
  • Release of carbon from decaying straw into the air contributes to global warming through greenhouse effect. Straw-based panels sequester carbon, thus eliminating this contribution to global warming.
  • Proper straw removal has no effect on soil tilth in Black soils. For Grey soils, straw needs to be returned to the soil only intermittently.

Concepts described in this fact-sheet were presented by numerous speakers during a seminar held in St. John, WA on June 12, 1997. Prepared by John D. Fouts, WSU Cooperative Extension.

Agricultural Sustainability. Highlights from a seminar series conducted by Washington State University's Ag Horizons Team and funded by USDA Western Region SARE.

Cooperative Extension programs and policies are consistent with federal and state laws and regulations on nondiscrimination regarding race, color, gender, national origin, religion, age, disability, and sexual orientation. The University of Idaho Cooperative Extension System, Oregon State University Extension Service and Washington State University Cooperative Extension are Equal Opportunity Employers.

John D. Fouts
222 N. Havana
Spokane, WA 99202-4799
Phone: (509) 477-2176
FAX: (509) 477-2087

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