The Problem with Silage Tarps
Next week, I will pull all the garlic, mow any residue, and then cover it with a tarp for two weeks to allow the weeds to breakdown below the opaque covering while I focus other things. It will be magically effective.
And I will feel nothing but conflicted about it.
Not just because it’s one of the four giant sheets of plastic I own that will be around (mostly in some useless, holy form) for the next thousand-ish years, but also because—in many ways—using plastic directly on the soil may be bad for the soil and the plants. Tarping creates an anaerobic environment and can cause some compaction and it’s possibly toxic for the consumer. Emphasis on possibly, but possibly nonetheless.
Let me explain.
Phthalates are a chemical often added to polyethylene plastics (like many silage tarps) to increase flexibility. Phthalates are also not great for people.
“In the past few years,” writes The Guardian, “researchers have linked phthalates to asthma, attention-deficit hyperactivity disorder, breast cancer, obesity and type II diabetes, low IQ, neurodevelopmental issues, behavioral issues, autism spectrum disorders, altered reproductive development and male fertility issues.”
Not a fun list—in fact, it reads like a list of all of the reasons consumers gravitate towards organic food to begin with: to avoid those things.
Although chemical uptake of such toxins by plants is very complicated, if the plants we are growing do take up those phthalates, then what the hell are we doing? Put bluntly, using a silage tarp becomes indistguishiable using any other toxic chemical. Further, as is the case with every agricultural chemical, the farmers and their families are at risk if high levels of exposure.
It’s worth reading this little thread in the forum posted by soilmatesfarm before passing any judgement on what I’ve written here or on tarps themsleves. Not all covers are created equally (there is a difference, for instance, between polyethylene and polypropylene ).
There are a couple important studies linked in that thread (like this one about a phtalic acid esters in Chinese soil or this review on plastics and soil degradation that touches on the issue of microplastic buildup) all very thought-provoking. To be sure, more research is obviously needed—plant samples, comparisons of different tarp production methods perhaps, etc.—but I think it’s important to emphasize that just because something makes our job easier does not mean it shouldn’t be scrutinized, nor adopted until proven harmful. Anything we put on or in our soil will become a part of that soil—and anything that comes from that soil—to some degree. Are we okay when it comes to micro plastics, phthalates or whatever else comes with tarping?
In no-till farming especially, the goal is soil and plant health. If the tarps don’t facilitate improvements in soil health, or if they directly harm it, I don’t know that tarps are a tool I can personally keep in my toolbox.
And I would really f****ng miss them.