Your 2008 straw is no different from your 2005 straw, except your new straw cost a lot more money to grow because of soaring input costs.
That presents a dilemma: Do you chop the straw and leave it on the surface to recover long-term nutrient value, or do you bale and sell it to recover some money?
Traditionally, many grain farmers have reached loose agreements with cattle producing neighbours. For the grain farmer, there’s an operating cost of dealing with the straw himself.
For cattle producers, the straw has value as bedding and can be incorporated into a feeding plan, so it is worthwhile to bale and remove it.
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As well, the grain grower enjoys easier seeding next year because the straw is gone. No money exchanges hands and everyone’s happy.
But escalating input costs have forced grain farmers to rethink the value of straw. Until recently, researchers and farmers have valued it at $30 to $50 per acre in terms of nutrients returned to the soil.
But now Guy Lafond of Agriculture Canada says farmers can bale all the straw they want without harming the soil or future yields.
The statement seems to fly in the face of what conservation experts have been saying for decades. However, Lafond says an ongoing 50-year study at Indian Head, Sask., shows no detriment from baling.
“The grain yield on the plots which were baled is identical to the grain yield on the plots where all residue was left,” says Lafond.
Not only were grain yields equal, but soil chemistry was also the same in the baled plots and non-baled control plots. Lafond measured organic carbon and nitrogen in 1987, 1997 and 2007. There was no detectable advantage to leaving the straw.
“During any straw baling operation, you are only able to remove 30 to 34 percent of the total above ground dry matter. I think 34 is the maximum you can expect to get.
“You don’t get the standing stubble, the chaff or the roots. And roots are the most important component. They contribute a lot. They exude a lot of carbon.
“So after 50 years of study, it would appear that 70 percent of the residue is enough to replenish the soil,” he says.
The study is specific to the Indian Head area, not to the entire Prairies, but it shows that ongoing straw removal is viable.
He cautions that the research deals only with normal available residue and farmers still have to leave enough standing residue for snow catch and erosion protection.
When the study started in 1958, it was a fallow-wheat-wheat rotation. Straw was left on the control plots and removed on the test plots, using the standard implements of the day. All plots were fertilized according to the latest methods of the day.
In 1991, the study was modernized by converting to no-till seeding. At that time, the fallow plots were converted to chem fallow. On the baled plots, three different grain harvest methods are used: straight cut-drop the straw-bale straw; swath-harvest-bale straw and stripper header-swath-bale straw.
Lafond is compiling the 50 years of data and writing the final report.
“The really positive aspect of all this is that if we’re looking at agricultural products for energy and manufacturing, we can harvest grain for human food and concentrate on making optimal use of the straw for these other purposes. I think that’s sustainable,” he says.
Ken Coles says in some areas, soil protection and moisture conservation may be more important than the nutrient value of the straw. Coles is an agronomist for the Southern Alberta Research Association and a farmer.
“In dryland farming here in southern Alberta, farmers see a lot of value in keeping their straw on the field,” he says.
“No. 1 for us is residual soil cover. When moisture is the big limiting factor, covering your soil is important. We want to minimize evapotranspiration.
“For us, the No. 2 factor is nutrient value.”
Coles says a complicating factor is the large number of feedlots in the area. Their straw consumption drives the price higher than in other areas.
Feedlot demand makes it hard to get a good grasp on the market value versus nutrient soil cover value. Selling to feedlots means instant payment. Waiting for straw to return its nutrients to the soil is a vague business transaction with Mother Nature that can take years.
“It’s hard to get an exact number (on nutrient value) because you have to spread the value of one year’s residue over many years because of the timing of the breakdown. And if your straw has a high nutrient value, the feedlots don’t pay more for it. It nearly all goes into bedding. So nutrient value doesn’t matter to them. It’s a straight supply and demand deal.”
Coles says that until this year, he has always left the residue on the surface on his own farm, even under irrigation.
“But this year, I had a feedlot come to me and ask if they could take all my straw. In return, they’ll spread manure on the fields where they took the straw.
“I think that’s a good trade. They need the straw and they’re running out of places to spread manure. For me, the manure will have more organic matter and nutrients than the straw.”
