Details on Swales
Here are some more details on swales. As I was working on them, I was struck by the sophistication of even the simplest of permaculture techniques.
Here’s a better diagram of how they work and how mine are constructed:
I had previously marked the paths out using a very simple contour-locating device I built ($5) from 2 x 2, a hinge, a cross piece of scrap wood, some fishing line and a weight. This forms a big “A” shape. Calibrate it by setting it up on a level surface and marking where the fishing wire and weight hangs crossing the cross piece. To use it, pick a starting point and then swing it around til the other leg hits the grass and the weight lines up, showing the legs to be level. Mark the new point with a stone and move on to the next point.
To actually dig the swales, first, I rented a rototiller ($39 for a half day) and loosened up the soil on the swale paths. Then I simply went along and dug with a shovel, flippiing the sod over onto the downslope side. After digging, I went along each swale and forked down and loosened a bit, just to put some depth for water to soak in.
Next I filled the swales with whatever drainage and organic matter I had handy. In this case, I had a bunch of gravel scraped onto my lawn from the next door neighbors winter plowing, so I put that in the base. Then I put in dead leaves which I had in profusion as I don’t rake them in the fall. Finally I put some ground bark mulch. This all went inside the swale.
I then scattered clover seed on both the ridge and the upslope side of the swale. The upslope side, being level, makes a nice path. Since the main path on the site runs downslope, across the swales, the swale paths are secondary cross paths. From these I run some keyhole garden paths upslope into the main garden beds defined by the swales and main path.
Finally, both the ridge and upslope side get a layer of straw mulch to keep them moist and deter weed and grass growth, while allowing the clover to sprout.
The fact that all of this works as an integrated whole where each part plays multiple roles was kind of impressive in a quiet sort of way. The clover helps seed the ridge, and will grow a good root system to keep it locked in place. It also adds nitrogen to the soil. The gravel and leaves were readily available and relatively easy to move. I would have had to scrape up the gravel anyway, so no big deal just putting it in the base of the swale. I mentioned that I use the upslope side for paths. I also noticed that laying the swales in broke up the garden space in a very interesting and useful way. The slope is now visible in the landscape, and it’s really obvious where the moisture is and isn’t in the ground, and where it flows. Little pockets and odd accute angles suggest places for anchor plants and shrubs. The garden starts to design itself.