Straw: hang onto it or sell it?

University of Saskatchewan soil scientist Jeff Schoenau said retention and return of crop residue is important to soil organic matter and fertility, contributing carbon, nitrogen, phosphorus, potassium and sulfur. If it is removed too frequently then it has to be replaced somehow.
 | File photo

The proponents of a wheat straw pulp mill in Regina say there is adequate straw for the facility if even just 10 percent of farmers within 120 kilometres commit feedstock to the project.

A study looked at straw availability within different distances around the plant.

Red Leaf Pulp plans to use 290,000 tonnes of straw each year to produce pulp for processing into tissue and packaging. It has announced a $350-million plant will be built next year.

That sparked debate about straw’s value, with some saying it should stay on the field for the nutrients and water-holding capacity it provides.

Joe Hinz from Red Leaf said the company is well aware of that view and has taken it into consideration.

“I know that there is value to cereal crop residue,” he said in an interview after a virtual presentation at Canada’s Farm Show. “Obviously there’s a certain amount of carbon that gets returned back as far as soil organic matter, (and) straw helps with that.”

But he also points to long-term studies done at the Indian Head research farm that found fields were able to maintain yields and organic matter when straw was baled because of the chaff and crop roots that remained behind. In that experiment only 40 percent of total residue produced was removed.

University of Saskatchewan soil scientist Jeff Schoenau said retention and return of crop residue is important to soil organic matter and fertility, contributing carbon, nitrogen, phosphorus, potassium and sulfur. If it is removed too frequently then it has to be replaced somehow.

But he also said there are places like the eastern Prairies where there is so much straw produced that it can slow drying in spring and hinder seeding.

Burning straw results in carbon and nutrient losses and many opt instead to make better use of it.

“Traditionally, this involves baling for animal feed and bedding, but more recently has been expanding to other uses such as fibre board, biofuel and pulp production,” Schoenau said. “Ideally, in the processing if some carbon and nutrients are retained in the byproducts of the straw processing, these can be returned and recycled through land application of the byproduct as a soil amendment. In so doing, this aids in replenishment of carbon and nutrients in the soil. I understand that this is the intent of the wheat straw pulp mill.”

Red Leaf has said it will produce soil additives.

Long-time Alberta agronomist Ieuan Evans said straw is valuable and should never be sold.

“If you’re a farmer and you get a 60-bushel crop of wheat, if you sell that straw off that field you need about $12,000 in compensation for that straw in terms of what you lose,” he said. “People don’t believe the 20-30 pounds of nitrogen that’s in the 1.5 to two tonnes of straw that’s in each acre. They don’t believe the potash that’s in it, even sulfur, water-holding capacity.”

Evans has previously listed 16 reasons why farmers should never sell a straw bale. He adds the fact that a truck moving the bales could bring disease into a field.

And, he says increasing soil organic matter by one percent will produce four more bushels of canola and five more bushels of wheat in a dry year because of the holding capacity created.

Hinz said the company is taking all concerns into account, noting that it’s up to farmers to choose what to do on their land. That’s why Red Leaf chose to locate where it did, he said, because the amount of wheat, particularly durum, straw available within a 120-km radius should provide its annual requirements.

The company will also be looking for a small amount of flax straw for use with one of its byproducts. Small wheat fibres unsuitable for pulp could be mixed with flax and the lignin from processing to produce a pellet that can be burned for energy.

Red Leaf does not intend to disrupt existing straw markets, he said, including what’s needed for cattle bedding and mushroom farms.

Bart Lardner, research chair in cow-calf and forage systems at the University of Saskatchewan, said that sector isn’t likely to be too affected by straw diversion. He said newer rotary combines mean less straw is available in the first place and producers would generally be more interested in barley and oats straw for feed. Wheat is much better for bedding, he said, although it can be used in cases of feed shortages.

Hinz also said Red Leaf will use several satellite sites on farms to store bales to reduce risk. The bales won’t have to be wrapped or covered; some spoilage is expected but quality for this process isn’t a concern.

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