Does Black Plastic Mulch have a place in Sustainable Agriculture?

mulch 2

When many of us think of sustainable agriculture, there is a set of stereotypes that come to mind. Green acres, bucolic animals gently grazing a flowering meadow, and people stooped in the fields endlessly weeding.  For me, my ideal never included the use of plastic, which on the surface, seems to be the opposite of organic in so many ways. What could be less sustainable then black plastic mulch?

Using mulch is a huge part of organic agriculture. There are so many benefits its actually hard to fully enumerate them. Reduced water consumption, less weed pressure, better soil texture, and at the end of the season, depending on what you used, you can till the mulch back into the soil. The soil on my farm is largely clay, so I have spent the last year turning in as much organic matter into the soil as possible. The goal is to eventually shift the soil towards something resembling sandy loam through cover cropping, green manures, mulching, and composting. Last year my mulch of choice was straw.

mulch early spring

I went a bit crazy covering nearly every piece of bare soil with straw. To a certain extent, this was great. The soil already looks better this year. But it was wet last year, and this year is already very sodden. I suspect that my fungus/blight problems were at least partly connected to the use of straw, which has a tendency to keep the soil moist and was starting to sprout little mushrooms. Last year the garden was newly tilled, so there was a lot of issues with grass coming back, and I spent too much time dealing with regrowth from clumps of sod I had hoped would decompose in the ground and add to the organic matter in the soil. The straw never seemed thick enough to suppress the tenacious blades of grass, so I thought I would try something new this year.

Mulch can also help to regulate soil temperature by either cooling or heating the ground through the albedo effect. This is where black plastic mulch can help with heat loving plants like tomatoes, peppers and eggplants. I have never been happy with my peppers. They are always so finicky and only grow in the hottest years, but this year I am determined! I expanded the area of cultivation significantly this year, with new sod turned under, so I thought it would be a good idea to cover those sections with a mulch that is a bit more impervious. I will be testing three different systems in order to see what works better, but the larger philosophical issue haunts me: should using a non-renewable resource be considered organic? Is this different than using gasoline to power my tractor? And if so, what would it mean to remove all oil from the equation? Are we ready for the labour involved, and who exactly will do that labour?


The first “test” is the standard drip tape/black plastic mulch combo. It is supposed to raise soil temperature and really help yields with tomatoes, eggplants, and peppers. The second is for a hugel bed I made for the asparagus and strawberry patch. Hugel beds involve a layering technique that creates raised beds by utilizing branches, straw, leaves, and other course materials that can provide a decade or more of fertility as the lower levels slowly decompose.  With so many twigs, branches, and leaves leftover from the ice storm, what better way to get rid of the “waste” than to raise an otherwise low patch and provide compost for these long lived perennials?

hugel 1

hugel 3

Since this patch is permanent, plastic was not an option. Instead, I have tried something called bio-film, a semi-permeable, and biodegradable plastic that will help keep the grass at bay for the first season. Next year I will go back to hay after the bio-film breaks down.

hugel 4


For me, the bigger question is: does plastic have a role in organic agriculture? It is allowed by organic standards, and many people swear by its effectiveness. On one level the question of waste is very important, since it is difficult to reuse the material at the end of the season, although I will try. However, organic agriculture is beset by a bigger issue of labour and needs to balance the very real need for sustainable, chemical free food, and the increased requirements for labour that this necessarily involves. Say what you will, the green revolution has allowed our farmers to become some of the most productive humans ever working the soil. Pesticides, herbicides, and other chemicals associated with conventional agriculture have lots of negative side effects, but they do one thing really well: save labour.

mulch 3

As a small farm owner, figuring out how to do everything that needs to be done, hour by hour, is a major challenge. Organic ag often relies on exploiting unpaid or lowly paid interns or migrant workers. In the long run, this is neither sustainable nor really desirable. I doubt many young people will hede the calling unless a living wage is possible. Until people are willing to pay the true cost of the food they eat, organic farmers will be stuck in a conundrum. Do I use a technique that is allowed, but not really in line with the ideals I hold, but can drastically increase yields and reduce my work load? Or do I hold onto those ideals and self-exploit my own time, or that of my interns?

mulch 1

This is why I think that initiatives like community gardens, urban agriculture, and farm-to-table programs are so important. The more people realize the labour involved in sustainable agriculture, the more likely they are to realize why good food costs more. I don’t know where I stand on black plastic mulch yet. We will see at the end of the season I suppose, but I am glad to see initiatives like the Halton Community Garden Network and the Halton Food Council encouraging urban agriculture. Knowledge is the first step towards change, and growing even a few vegetables or herbs can help shift your understanding of what it takes to eat without degrading the land. You may not provide all, or even a lot of your food, but at the end of the day, that small plot you tend on your balcony, back yard, or in the community garden will help you understand what is involved in sustaining us every day.