I am really interested in this topic! The church where I am on staff has two or three acres of green grass, which we don't do anything with, other than water and mow. I'd love to create gardens that provide food for hungry people. Can the grass be just rototilled under and a garden planted, or is there concern about remaining lawn chemicals in the soil?
I would not till it, I would build raised beds with a layer of cardboard, newspaper, etc to kill the grass inside the beds. Leave the grass in between beds for paths.
Or go with a gradual takeover of the area with various trees, etc in true permie fashion, sculpt the area, again with grass-killing layer of paper, cardboard, etc (I have used old carpeting flipped over fuzzy side down) and just build beds on top with scrap wood , chips, compost, grass clippings (quit using chemicals!!), manure,spoiled straw, etc and plant away.
Basically that is what I have been doing to my gravel pit of a yard for the past 12 years. I have "framed" my plantings with the abundant big rocks, sifted the remainder to pebble and sand size (the sifting done with a milk crate and shaking), filling driveway potholes with the bullrock and gravel, then layering anything that will rot and make soil inside the beds. We have used cottonwood logs and branches for "framing" as well (makes lousy firewood).
Sorry for cross-posting, but check out no dig vegetable gardening and the site charlesdowding.co.uk and www.incredible-edible-todmorden.co.uk
He recently started a market garden from scratch by covering a field with 6in of composted cow manure, cardboard on walkways with some woodchips on top. No need to rototill. You can find out how much chemicals and which were put on the lawn but I wouldn't worry too much, most of the food we buy in a supermarket is subjected to a load more nastiness and we still eat it (some of us that is)
Framed beds as Mona suggested look very pretty, you could actually put a few beds on top of the lawn like that, for starters, and mow between them. If you want groups to work these beds (great way to socialize) keep the paths wide, 1m or so, and the beds at 1.2m (so one can reach the center of the bed without treding on it)
The more people you can get involved, the better. Especially those who will benefit from the food you grow.
And watch the new community garden video from Geoff.
If you do a few little things like curving the beds and creating sitting/reflection areas in places, it will have a lot more aesthetic appeal to satisfy the cranky neighbor, church member, or town council. Beneficial flowers along the edges help with that, too. Helps feed the soul, as well.
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