Flax straw is the fibrous stalk of a flax plant, left behind in the field after the flax seeds have been removed during combining.
Unlike the straw of other crops commonly grown on the prairie, flax straw has a long history of being utilized, primarily for the strong fibers it contains. The ancient Egyptians produced fabrics from flax and wrapped their mummies in linen cloth.
First introduced in Canada in 1617, flax was often one of the first crops planted as settlers moved across the country and broke ground. It's an excellent crop for the prairies because it matures even under cool, short-season growing conditions.
There are two broad categories of flax varieties: oilseed flax and fiber flax. The vast majority of North American producers grow oilseed flax. These varieties tend to be short, highly branched plants, because they were bred to maximize the number of flowers (and hence the production of seeds). (ODA-OSU Oilseed Project, 2008)
The tough stem fibres in flax straw decay slowly over time making it difficult to incorporate the straw into the soil after harvest: the fibres tend to wrap themselves around and/or plug disks, wheels and tillage points.
Because of this, farmers have traditionally managed flax straw by dropping it in windrows behind the combine, then either burning it there or raking it into piles and then burning it.
More recently, combines with straw choppers have been developed to chop and spread flax straw adequately.
In 2001, Canada produced 720,000 tonnes of flaxseed, and 720,000 tonnes of straw to go with it. It's estimated that 570,000 tonnes of that could be sustainably removed. (Wood and Layzell, 2008)
Although flax straw could conceivably be used as a feedstock for the production of biofuels, its fibrous nature makes it useful for a number of other bioproducts. Oilseed flax fibres are already being used in specialty papers and to replace fibreglass in automotive parts such as dashboards and door panels. Many other potential uses for the fibres are being researched. (Flax Council of Canada, 2008)
In order to get more insight into the many advantages of flax straw and all it encompasses, there are four essential elements:
The goal of flax straw processing is to separate the useful fibres from the other parts of the stem.
Although flax straw has, in Canada, traditionally been seen as a problem to be managed rather than a valuable resource in its own right, that view is beginning to change as the existing market for straw expands and new technologies hint at even more exciting uses for it in the future.
Oregon State University. 2008, Flax. OSU-ODU Oilseed Project, (March 28, 2008).
Wood, Susan M. and Layzell, David B., 2008, A Canadian Biomass Inventory: Feedstocks for a Bio-based Economy, BIOCAP Canada Foundation, Queen's University, (March 28, 2008).
Flax Council of Canada, 2008, Growing Flax: Flax Straw and Fibre, (March 28, 2008).
For more information on these documents, please refer to the Department of Crop and Soil Science at the Oregon State University, Ag-West Bio and/or The Flax Council of Canada