Our house was built 41 years ago. An acquaintance said he remembered when that piece of land was a farmer’s field. I assume it had gentle rolling hills like the bare land just a couple of blocks away did when we first moved in. When our subdivision was developed, I bet the standard earth movers / scrapers were all about leveling some of the area for the streets and lots and later redistributed the topsoil into the back yards.
We arrived three years after the houses were built. I heard stories of the previous halfwit owner and his neighbour. There was a very slight slope from the backyard towards the house and the Tweedle Brothers decided that was a dangerous source of flooding. So, Dee and Dum hired a contractor with a tractor and truck to haul topsoil off their properties to level it out. I’m sure the contractor was smiling; he got to sell the topsoil too.
When I arrived, the half of the back lawn closest to the house quickly dried out in the dry summers – the topsoil was much thinner there. But my vegetable garden was on the slightly higher, rear half of the yard. It had a pleasant 10 inches of sandy loam topsoil.
For the next 37 years I mowed the lawn, always leaving the clippings to fall back into the lawn. This gradually rebuilt the depth of topsoil. Most virgin topsoils in the area are only 10,000 years old since the last ice age receded and mine is made of the sand and gravel it stands on, volcanic ash from eruptions of Mount Baker and Mount Garibaldi, dust that has blown in, and the organic matter that has built up from the forest and vegetation that grew here.
Last year with lockdowns and shortages I opened up a section of the lawn and created four more 50 square foot beds. This was on the part of the yard with the thinner topsoil. I had about 6 inches of topsoil after shaking out the sod. I’ve raised that a bit more by mining some of the soil from the paths between the beds. Now I wish I’d fertilized the back yard lawn over the years with some chicken or other manure, like I’ve done with my small front yard, and built up the soil even more (although that would have required more frequent mowing).
Without topsoil I’d have nothing. In my opinion, people who think they can incorporate the garden centre’s ‘Garden Mix’ is in for a hard way to grow productively. That stuff is mostly sawdust and sand. Take a look at it under an eye loupe or magnifying glass. It’s partly composted to make it look loamy and black and beefed up with some nitrogen for the first year’s crops. But during the following number of years it becomes a nitrogen sponge as all the carbon uses up all available nitrogen as it decomposes, slowly. I’d stick with real topsoil.
Not all marketed topsoil is topsoil. If there’s nothing growing on the top of the pile it probably isn’t. TOG and I watched another community garden start in a church gravel parking lot. Some fine member donated loads of topsoil and the gardeners were free to use as much as they needed. One problem – it was full of weed seeds, specifically, morning glory. They came up everywhere. That was a recurring pain.
Another strange thing with that group was it seemed no one loosened up the hard packed gravel underneath their garden plots. They just poured on the topsoil and planted. TOG and I just looked at each other and said what we often say: “They don’t know!” I assume that over several years the roots, bugs and microbes have managed to loosen up the ‘subsoil’ but I would have been there with a pick or broadfork to open up access to the under story of the beds.
TOG’s one and a half acres that he market-farms has a different topsoil signature. He’s on bottomland in the Sumas Prairie with a soil built up over the centuries from the constant flooding of the Fraser River. It’s a nice deep silty-loam with no stones or rocks. When he got the lease, he reluctantly had it turned (plowed) to get a quick enough start on the growing season.
It had been a hay field for a good number of years, usually cut before the grasses went to seed and appeared to not have had any horses on it, so the weed seed count was nice and low. He did have the pasture's population of crane fly larvae (leather jackets) and those caused some problems the first two years.
TOG also found he had two areas that were lower fertility than the rest. He speculates that the field originally had a few bumps that were shaved off and that left a thinner topsoil in those two areas. It was solved with his soil building, sustainable gardening techniques as well as a double portion of well composted horse manure.
There was one other thing TOG got with his piece of land. He uncovered the thinned remains of a farmer’s antique garbage dump. There was nothing left but bits of metal and some very colourful broken glass all spread out in the soil over a couple thousand square feet.
A good topsoil is so much more than just dirt. It’s living and active, full of life and nutrition, and needs to be sustainably nurtured and cared for. I believe the day could soon come when the quality of our topsoil could determine whether we’re Dirt Poor or Filthy Rich.
Happy Gardening.
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