The Most Important Four Inches In Your Garden


| 5/18/2011 7:48:01 AM


Tags: gardening, topsoil, double digging, Cam Mather,
I delivered one of my books to a friend in town recently. She had borrowed “The All You Can Eat Gardening Handbook” from the library but had decided that she wanted her own copy when she realized that she’d be referring to it throughout the gardening season. She asked me about getting her garden started this year. She had removed the grass and was now trying to get the garden ready to plant. She was hesitant to rent a rototiller because she was afraid she might break it on some rocks, and I don’t blame her. We live in “Stone Mills Township” and the one thing that we grow well in our gardens and our fields is stones. And every year the frost heaves a few new ones up and I manage to hit them with my rototiller. Luckily I’ve never broken it on a rock.  

I asked her what she had done with the layer of sod she had removed and she pointed to a low spot where she had used it for fill. I suggested that it would be a good idea to retrieve that sod and put it in the compost heap. Or just pile it up with the grass facing down and cover it with old hay to kill the grass but keep the topsoil. Topsoil is really, really precious, especially in a place like this. When the glaciers retreated eons ago they left very sandy soil with lots of “big” grains of sand (i.e. stones. Part of my garden looks a bit like a small gravel pit.

I can’t remember the exact figure but I think I’ve read that it takes something ridiculous like 50 years to build up an inch of good topsoil. So if you had trees and they dropped their leaves every year and these rotted and earthworms chewed them up and pulled them into the soil, it would take a long time to make a significant amount of soil. So when you remove that top 2 or three inches of topsoil along with the grass, you’re removing the most valuable component of your new garden. When I lived in the city there were a few days each year when yard waste was picked up with the garbage. Some people would leave big piles of perfectly good sod at the end of their driveways to be picked up. People in the city have the money to head over to the big box store to load up on bags of topsoil to replace the topsoil they’ve thrown out. I don’t.

So save your topsoil at all costs. In my book I talk about why I am such a big fan of using rotten hay to expand my gardens. If I put it on thick enough it will kill the grass. I have to leave it a full season for it to work its magic, but I can usually anticipate where my next garden is going to go and so I can invest a full season in killing the grass. Hay is great because it allows water to trickle down through. And it decomposes, so when I’m ready to till it in the following season, not only have I killed the grass, but also I’ve added significant organic matter to my soil. I like to think of hay as “bio-mass”. Some farmer had a big field and this grass grew tall in some previous summer’s sun. It used photosynthesis to make all this wonderful grassy, woody biomass. And since an animal didn’t eat it, I’m now going to incorporate that stored sunshine energy into my soil. I absolutely love it.

The other reason I love using rotten hay is because it doesn’t disturb all that life in the topsoil that I want to maintain. All those wonderful microbes and microscopic little creatures that help organic matter to decompose, or help to free up trapped nutrients and minerals that might be locked in some of that organic matter, so it’s available for the new crop to absorb and pass along into this year’s fruit (or vegetable). This is really important. Again I can’t remember the exact statistics, but some biologists have suggested that there’s more life by weight in the top couple of inches of topsoil, than in all the living creatures that live on top of the soil … humans, cows, elephants, NFL linemen, etc. So when you dig up that topsoil and get rid of it, you’ve lost all those wonderful microbes that your plants need.

If you want a garden fast and want to preserve your topsoil you can just dig up the sod and turn it over. The problem with this method is that it usually doesn’t kill the grass, which will just turn around, and start growing back towards to the sun.

Instead you might want to try “double digging.” Put on your work boots and sharpen your shovel and cut the sod in the area where you want the garden to be into 12” inch squares, like a checkerboard. Take the first row of sod that you remove and place it about a foot from where you dug it.

wayne31r
6/1/2011 8:01:05 AM

Why not save the effort of double-digging and just make a lasagna garden? Just Google the term or see http://www.motherearthnews.com/Organic-Gardening/1999-04-01/Lasagna-Gardening.aspx. One way is to put down a layer of wet cardboard or newspaper, which will suppress the grass. Follow this with as much hay, mulch, and organic material as possible. If you want to use the garden this year, top it off with some pockets of topsoil into which you plant your vegetables. Voila! Oh, and sell the rototiller before your neighbors learn this trick. ;-)


wayne31r
5/27/2011 9:09:12 AM

Why not save the effort of double-digging and just make a lasagna garden? Just Google the term or see http://www.motherearthnews.com/Organic-Gardening/1999-04-01/Lasagna-Gardening.aspx. One way is to put down a layer of wet cardboard or newspaper, which will suppress the grass. Follow this with as much hay, mulch, and organic material as possible. If you want to use the garden this year, top it off with some pockets of topsoil into which you plant your vegetables. Voila! Oh, and sell the rototiller before your neighbors learn this trick. ;-)


vacuum1313
5/25/2011 6:25:02 PM

I follow a bit of a different regimen. I collect old jute backed carpet, cut it into 1' wide strips. In the spring or fall before planting mark the rows 1' apart and use a mini tiller to loosen the only in the strip to be planted. Pull out and shake the grass out that reclaims most of the soil and compost the grass. Lay the carpet down, jute side up and about 1" apart where the plants will come up. As the tilled area is >1" the carpet sufficiently overlays the remaining grass to kill it without all the work of digging everything. The carpet keeps you clean, the weeds in check and reuses material destined for landfill. Straw bales are used the 1st year to insulate around the base of the house, the 2nd year as edging around the garden and then worked in the 3rd year.





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