In 2011, I took a course at McGill in Organic Soil Fertilization where I learned that my yard’s soil type is loamy clay (with a lot of rocks in it – I actually look forward to digging them out and collecting them on the surface, if they’re bigger than a quail egg). I also learned that soil microfauna, like isopod “pill bugs,” centipedes, and worms, are essential for soil fertility. They are our little decomposer friends, grazing on bacteria, fungus, carbon sources, and occasionally on each other.
Dirt is a living mass, it’s not supposed to be sterile.
A couple of years ago, I reconfigured the deck as I was changing the set up of the garden. As I lifted various parts of the deck, I noticed the soil was quite moist and rich, sheltered from the heat.
Soil macrofauna, like rodents, amphibians, and others who burrow to make nests and passageways, are soil engineers. They are particularly responsible for distribution of seeds and nutrients.
Over the years, the soil underneath my back deck has been a home to ground-dwelling bees, a rat or two, and a family of skunks. I don’t mind the wildlife, especially the skunk, who is a good neighbour, apart from eating my lilies. (A tip for dealing with the skunk’s latrine: throw down some dolomite lime). And their presence does the soil itself some good. It had been tunnelled, turned, and fertilized by all the species of animals I know and don’t know.
The state of Victoria in Australia has a good guide to soil health here.
Soil remediation in an urban context
In 2010, I participated in the École d’été sur agriculture urbaine, when I asked Eric Duchemin, Associate Professor of Science and the Environment at UQAM, some questions about remediating landscapes and urban soil and returning it to primary use — that is, forestry and agriculture.
He did not say “it’s impossible,” but that is what it comes down to. There are two reasons why. When it comes to agriculture, the Province immediately declassifies built land into a class that you cannot farm on. The things that happen to land when you
- “improve” it by removing natural cover and features (forests, vegetation, and water features),
- prepare and build on it,
- occupy and use it, and
- eventually demolish structures
– All of these poison and destroy the soil.
This image shows you the relative availability of metallic nutrients, depending on the pH of the soil solution (water in soil):
From the graph: the general availability of metals for uptake by plants is strongest as the soil gets either more acidic or more basic. If you keep testing the soil and keep it within range, you should be able to keep the metals in the ground and not in the foliage you eat. Or, if you do decide to do something about chelating the metals, or change the pH and put an acid-loving plant in place, you may be able to remediate the metallic content of the soil.
Keep in mind while gardening: don’t amend vegetable gardens with cow manure. It contains a lot of trace metals as a consequence of biomagnification.
The gist of soil remediation is: excavate the soil, install a certain kind of liner, ship out that soil to remediate it for metals (hydrocarbons are rather easy to biodegrade in place), and then put it back in place or replace it with new soil from somewhere else.
These would be the requirements if you were to farm the land by planting forage crops or crops for human consumption. So basically: you can’t. Legally, at least. The legal process and cost of remediating soil is prohibitively expensive.
This boggles my mind: why then are we so careless that we allow anything to happen to such an extent that not only for a garbage dump (landfill), but for ANY soil, we must compartmentalize it away from the underlying geology, in order to protect what remains?
My take: while I’m a pessimist in some things, I do think that Environment, Health & Safety (workplace EHS) can be a legalistic cult at times. Here I err not with them, but on the side of optimism, science, and heritage values. I believe we can find a practical mix of crops, livestock, and supplies that would allow farming on former city land.
Because, given time and inspired action, soils do get remediated. Hydrocarbons? Add pipes to the soil so that it’s aerated; an aerobic environment lets soil microbes metabolize them. Salinity? Osmosis. Halophytic plants. Mycorrhizae metabolize a variety of substances, and they can work surprisingly fast.
So I’d recommend rather than just abandoning the land (though, that helps biodiversity anyway: vacant land is niether disused nor empty!), use it and make healthy structural and biotic amendments to the soil for various purposes anyway. Build it back up to health over the long term. If the quality of its outputs matter, such as plants to feed ourselves or animals, we test them, and handle them according to test results.
What else can we do instead with the land?
Restoration of landscapes from urban features
You could use de-developed land for animal agriculture, provided you bring in the food from somewhere else, because the animals will not be getting enough healthy forage from plants growing in compacted and potentially contaminated city soil. The tracts of land will not be big enough to support medium- and large-scale livestock farming.
The only alternative to redeveloping a brownfield in Quebec is restoring it to parkland and forests. De-developed land is a prime candidate for often-needed parkland, and this can let the long biotic/geological processes ameliorate the soil – especially assisted by animals, such as introducing a burrowing species, or even introducing beavers, who are the best landcape engineers! It does good even if the parkland remains in a secondary, poorer state, groomed for sports play and horticultural use, without natural water, meadows, and forests springing up. Even so, people have an appetite for these.
Furthermore, if trees will grow, who is to disallow silviculture – the planting of trees for commercial use, such as a tree nursery, or a lumber/paper plantation? Why would they? Even ¼ of an acre is a respectable stand of trees.
Eric told me, apparently, city people don’t like forests. I don’t believe this. This is seriously vexing. Our culture here used to dislike forests, but despite still having a preference for overly groomed, horticultural forests (and a silvicultural approach fits!), our appreciation of them has changed for the better. So I have some reason to be optimistic.
There is still a problem with democracy, because its primary purpose is to valourize money changing hands with the least amount of conflict. And there is a lot of value to having a peacable society where people can at least have their say, even if it only amounts to a lot, a lot of talk (while actions speak otherwise). The long-term good of the people and stewardship for the future are of little real importance, and so there is a vested interest in zeroing out nature in the first place to protect the commercial interest.
Show people only cityscapes, they will think cityscapes are good and non-cityscapes are just real-estate-in-waiting. Show them a forest, and they think something akin to leisure and vacation. The worst of them consider it lost opportunity. But why should we allow or require people to prefer what is obviously bad (defunding nature and subordinating it to development is obviously bad!), and perpetuate misinformation that it’s good because… money?
One thing that helps us maintain theses goods is public ownership: holding park land in trust for the use of all (or otherwise managed by the city as a woodlot or garden allotments). Still, it’s in the back of municipal officials’ minds, as always in the forefront of developers, that this land is held in escrow for future development interests. Then they can sell the idea to the public with they idea of “urgent need for…” space that they’ve already misallocated amongst the built environment, also known as ‘inventory.’ (That’s not a link, that’s a key point.)
So with the eventual threat implied by public ownership in mind, newly de-developed forest land should also be privately owned by a wealthy person, foundation, or trust, to be held in perpetuity or until the powers that be threaten eminent domain. Alternatively, in private hands, it can put under a conservation easement, to provide for its ecologic use and make improvements to it down the years.
When you consider how long it takes the geologic processes of this world to form soil, it is no surprise to me that we have to treat it gently. We have to preference building on brownfield, and outlaw building on “greenfield:” farmland, wetland, and forest. And we have to improve the way we handle development in the first place, and the remediation of brownfield so that the cost is less prohibitive than what it is now, with toxic soils. Finally, we need to include de-development as part of the options when we no longer have use for the things we’ve already built. Maybe start by planning “exit” strategies for every development that is made, with a fund to make sure they happen.
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