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Tarps versus grain bags

For farmers short on storage, tarps or grain bags can be a low short-term 
solution. It’s not risk free, but these five tips can improve your odds

Farmers short on storage this year might consider tarping grain or using grain bags. But neither is good for long-term storage or high-moisture grain.

Farmers short on storage this year might consider tarping grain or using grain bags. But neither is good for long-term storage or high-moisture grain.

Tarping dry grain on the ground is okay for a day or a week, Dr. Chelladurai Vellaichamy says, but not any longer.

Chelladurai Vellaichamy is a Ph.D. student in biosystems engineering at the University of Manitoba. Vellaichamy and his colleagues have been researching canola storage in grain bags for three years, with support from the Canola Council of Canada and Growing Forward.

Vellaichamy says tarping high moisture grain is likely to cause mould growth and other problems. Humidity can also be high during harvest. “So that also makes it a difficult case if we just store it after harvesting right on to the ground.” 

Grain bag results

High-moisture grain can be stored in grain bags for a few weeks maximum.

Vellaichamy and his colleagues stored canola with eight per cent, 10 per cent, 12 per cent, and 14 per cent moisture content in grain bags. They found canola with eight per cent moisture could be stored for up to 10 months without com- promising quality. Canola at 10 per cent moisture could be stored for six to seven months, and 12 per cent about five months.

But once canola hit 14 per cent, it started to deteriorate within about a month. Vellaichamy says there was mould growth and cak- ing in 14 per cent canola.

Moisture content in grain bags isn’t likely to change over winter as long as they remain sealed. But once the weather warms, condensation can collect at the bag’s top.

Even dry grain should be unloaded from grain bags before the temperature hits 10 C or 15 C, or it may be downgraded, says Vellaichamy. Last year researchers unloaded some No. 1 canola in late February, and it wasn’t down- graded. A second batch unloaded the first week in May dropped one grade, and canola stored in grain bags until August fell to feed quality.

Grain bags are quite airtight, so when grain respires, it increases carbon dioxide concentration and drops oxygen content. “So that creates a condition where… insects or pests can’t grow inside,” Vellaichamy says. Grain bags can be fumigated as well.

Rodents and birds can rip holes in bags, making them less airtight. Farmers should try to seal any holes so the bag remains fairly air tight. Vellaichamy says special tape provided by the manufac- turer works best, but it doesn’t

work well below -5 C or -10 C. Vellaichamy and his colleagues have also tried closing holes with duct tape and sealing styrofoam,

but the special tape works better. Farmers should make sure they

can get to the bags at all times. “You can’t put those bags in

the middle of the field where (they’re not) accessible to the trucks or anything. Because if something goes wrong we have to unload it right away, even at the peak of winter time,” says Vellaichamy. 

Five tips for ground preparation

Ground preparation is an important fact for both tarps and grain bags, says Vellaichamy. Here are five tips:

1. Make sure the site has good drainage.

2. Clean the ground, removing any sharp objects, such as rocks, that might pierce the bag or tarp.

3. Pack the ground really well. Pressure needs to be applied while loading grain bags, so it won’t work well if the ground is soft.

4. Cut grass to keep rodents away.

5. Apply lime to the ground before placing the bag, and around the bag once it’s in place. Vellaichamy says they didn’t see a single rodent after using lime.

If tarping grain, make sure the tarp is secure. Some companies recommend using an aeration fan at the bottom to keep the tarp on, Vellaichamy says, but he hasn’t tried this.

Grain bags and tarps may seem low-cost, but farmers should take into account costs of a grain bag- ger and unloader, and any money they might lose if grain quality is downgraded.

“If you erect a bin in your yard, it will last at least 15 (to) 20 years. But these bags are one-time use,” says Vellaichamy. 

Costs of bins versus bags

Mike Pylypchuk, a business management specialist with Saskatchewan Agriculture, ana- lyzed different grain storage sys- tem costs in 2012. Using numbers provided by Flaman’s in Southey, Saskatchewan, he compared the cost of using flat bottom bins, hoppers, and grain bags to store 120,000 bushels.

The bottom line is the annual cost for grain bags came in at $0.37 per bushel, while the flat bottom bins cost $0.38. Hoppers cost $0.59 per bushel each year, according to Pylypchuk’s calculations.

Pylypchuk assumed the bagging system would last 10 years, and bins 25 years. He didn’t include power costs for operating PTOs or power carts. Farmers can use a custom rate calculator to figure out these costs, which is available at tom_rental_rate_guide.

Pylypchuk used a two per cent spoilage rate in the grain bags, and no spoilage in the bins, which evened up the costs between the grain bags and flat-bottom bins. The actual spoilage cost will vary with crop prices. Pylypchuk encourages farmers to plug their own numbers into his spreadsheet. To get a copy of the spreadsheet with instructions, email him at [email protected] 

About the author

Field Editor

Lisa Guenther

Lisa Guenther is field editor for Grainews based at Livelong, Sask. You can follow her on Twitter @LtoG.



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