PDC Day 10: Earthworks

Permaculture is labour-intensive in the beginning, but saves work in later years. By moving the earth around a bit according to a well-designed plan, we can control the elements somewhat – water, wind, sun, frost – so that they make life easier in the long run. It’s a lucrative retirement investment plan that also yields big dividends for the earth.

Swale with ditch and berm

In our climate, swales are the most common permaculture earthwork. You might think they are just raised beds as you see in many gardens. In fact, they are carefully engineered – but don’t be daunted because they don’t require fancy equipment and they don’t require an engineering degree to execute!

A swale consists of a long shallow ditch and a low berm built from the soil taken from the ditch. It can usually be dug by hand – though doesn’t have to be.  Swales collect rainwater and runoff, and spread it out along their width, encouraging it to seep into the soil to nourish the roots of the plants growing on the berm. The ditch can be filled with woodchips and inoculated to grow edible mushrooms.

Slate close to the surface challenged our strongest efforts to level the ditch. Maybe it's time for the heavy machinery!

Swales are built on contour. That means they follow the lines of equal elevation that you see on maps. We learned some different ways of marking the contours on the land.  You can be sure that we’ll be running workshops on basic surveying and swale digging, passing this knowledge on, so stay tuned.

Stakes in the grass mark the contour as measured by students using the A-frame level, while Graham sets up the transit level.

The most precise measurement is the level at the bottom of the swale. It must be absolutely level along its length so that water doesn’t pool in one place.

The other major earthwork used in permaculture is the pond (called a “dam” in Australia where these ideas originated). A pond can serve many uses, from fire safety to gravity fed irrigation to micro hydro to raising fish and ducks.

Graham went into much interesting detail about kinds of dams or ponds, where and how to build them depending on the contour, and construction techniques.

If you are planning to do permaculture on a large property, you should definitely study this issue further.  Water control should be designed before road access and house site are determined.

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