Focus on...Agricultural Plastics

Farm plastic has been getting increasing attention lately. In part this is a result of the increasing popularity of heavy plastic bags for storing grain, which was evident in the recent harvest. Those long, white tubes that look like giant caterpillars are becoming a common sight.

According to the Western Producer, prairie farmers use an average of 12,000-16,000 grain bags a year. Given that the bags weigh between 135 and 315 kg apiece, that's a lot of plastic.

Grain bags and silage bags are made from polyethylene (LDPE - plastics label #4) and have the same underlying chemical composition as the basic plastic shopping bag.

Another common use for plastic on farms is to wrap bales of hay and straw. Plastic twine is made from polypropylene (PP - plastics label #5), the same basic composition as containers for dairy products like yogurt and sour cream. Bale wrap products are most often made from high-density polyethylene (HDPE - plastics label #2). This is in the same plastics family as milk jugs and shampoo bottles.

All of these types of plastics can technically be recycled, but there are special problems with agricultural plastics. First, they are all used outside and get dirty and coated with stuff - silage wrap and bale netting especially. Traditional plastic recyclers can't really handle dirty plastics without adding washing equipment. This adds to the cost. In many cases, recyclers would be making the same product whether or not they used ag plastics for their source. This means that the profit margin (such as it is in recycling...) would be higher for non-ag plastics that don't need additional cleaning.

Second, gathering the plastic for recycling can be a challenge. A spent grain bag is big and unwieldy, unless you have one of those slick machines that rolls it back up as it empties it. Even then, it's pretty heavy and difficult to get to a recycling depot. Silage wrap can get very dirty and stick to the ground, especially in winter. Twine and netting are easily tangled and hard to work with.

No one in Saskatchewan is accepting ag plastics for recycling, and manufacturers are not willing to take them back. This leaves farmers with two options: bury or burn. Taking them to a landfill still requires gathering and transporting them and some landfills have started to refuse ag plastics.

Burning ag plastics seems to be a fairly common practice, but it carries significant air quality concerns. There are a lot of chemicals added to plastics to give them the optimal properties and open burning of these can generate toxic fumes, as well as pollute the land and groundwater. We've got to find a better way to deal with these products.

(Source: November 2009 WasteWatch)

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