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The last straw: nine ways to handle flax straw

The problem of what to do with the straw after the crop has been harvested has been slowing producer acceptance of flax for generations.

Burning is the traditional method, but there are other options.

Allen Kuhlmann of Rouleau, Sask., said he feels the problem gets more attention than it should.

“Especially with prices where they are. This year the price may act as an incentive for farmers to deal with the straw,” said the flax producer and chair of Saskflax, the regional growers’ association.

Canada is the world’s largest exporter of flax. However, in recent years producers have reduced seeded acres from more than 2.2 million annually to about 1.3 million acres last year due to low prices and higher yields from crops such as canola.

“Big gains in canola yield have gotten it to 35 bushels or so. Prairie flax averages 22 bu. (per acre). It’s left flax in a tough spot,” said Kuhlmann.

However, the shortfall in acres has produced a windfall for those who grew the crop as prices pushed past $18 per bu. in recent weeks.

Those high prices should ensure good seeded acreage for 2008, say analysts.

Kuhlmann said attracting new producers to flax can be as tough as the crop’s straw.

“For lots of folks they look back at their fathers having grown the stuff years ago. Swathing it wasn’t much fun as straw wrapped around everything. Then you had to bunch and burn it (after threshing),” he said.

“Now they are reluctant to add it to the rotation. But there are options and with research and market development for fibre products there will be a lot more in the future.”

Flax straw holds linen fibre in tight, waxy bonds around a hollow straw core. The tough fibre means that flax tends not to lodge and stands up well to cold and heavy snow.

This also means it withstands producer attempts to cut and chop it for spreading onto fields.

Most varieties of oilseed flax grown on the Prairies are deficient in the long, fine fibres prized for the textile industry. However, the fibre the oilseed provides is sought after in some markets. Researchers are seeking to develop more uses and crop varieties.

Alvin Ulrich of Crop Fibres Canada in Saskatoon told agronomists, researchers and producers attending the recent Soils and Crops Workshop in Saskatoon that producers have many choices when it comes to dealing with the wiry straw, including some limited marketing opportunities. He presented nine options.

Option 1

If the straw can’t be sold or tall stubble is necessary to trap snow or prevent fall wind erosion, then swathing, combining and chopping with the combine chopper may be the right path to take.

“You need a chopper that is in good condition and big enough for flax. Most of the bigger combines can do this pretty well today. Many producers don’t know their combine chopper will handle the job,” said Ulrich.

Option 2

If there is no straw market or the field is weedy, the crop can be straight cut, leaving less than 18 centimetres of stubble to catch snow. The straw is chopped and spread by the combine.

“If there is no practical local market for straw and you have no other use for it, straight cutting relatively low means you can chop more of it to return the field,” Ulrich said.

Option 3

If there is no place to sell the straw, harvest the oilseeds high with a straight cut header or use a stripper header, leaving tall stubble.

This requires a direct seeding drill that can handle planting in tall stubble the following spring.

“But many (air drills) can seed into tall flax stubble without difficulty,” said Ulrich.

Option 4

If marketing the straw isn’t an option and the combine mounted chopper isn’t up to the task of chopping flax, it can be chopped and spread using a forage harvester.

Option 5

Harvest the crop and drop the straw in windrows, with good soil contact to ensure some retting, or rotting, takes place. As late as possible in the fall, the standing stubble and straw may be heavy harrowed.

“After two or three passes you won’t even be able to identify the crop,” he said.

Option 6

Drop the straw from the combine into windrows. Bale it for use as livestock shelters, for farm heating in boilers or for marketing as biofuel, if the market exists. This straw may be damaged by combining with a rotary machine, but that isn’t an issue for these uses.

Option 7

Combine the crop and drop the straw in windrows. Bale the straw for sale of the fibre where it isn’t used for textiles or where other long, undamaged flax straw is required. Rotary combining may be acceptable.

Option 8

Where there is the possibility of selling flax straw as fibre for textiles or specialty industrial use, producers should harvest the seed separately from the straw.

Combine the crop using a conventional combine to avoid straw damage. In a second operation use a rotary mower to cut the remaining stubble down to about 10 cm and spread the straw dropped from the combine so it can be packed against the soil by a land roller or sheep’s foot packer. Some stubble remains and the snow catch is still significant, said Ulrich.

Allow the straw to ret throughout the winter and in the spring rake the material into windrows and bale the short lengths of fibre.

Rotary mowers can be adjusted to drop the stalks with limited amounts of recutting within the mower housing.

Some mowers are now being designed in Saskatchewan with this option in mind.

Option 9

Where the fibre is of high quality and the long length needs to be preserved, the crop can be taken first for seed and then for fibre, as in Option 8. However, this approach doesn’t leave much stubble as the mower cuts down the cuticle of the plant’s stem.

Straight cut the crop high or harvest seed with a stripper header.

Cut straw with a rotary mower, pack and leave to ret in the field until late fall or spring before raking and baling.

Snow capture can be accomplished by leaving narrow rows of standing stubble in the field, said Ulrich.

“There is a 10th way to look at dealing with flax straw. But lighting a match seems like a waste of nutrients, energy or fibre,” said Ulrich.

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