PDC Blog: Day 4
Jump to: Creating an A-frame, Capturing water run-off practical or Building swales
After everyone had their goji berry and banana smoothie (and of course, porridge for those who wanted) we began our daily game, which I called ‘Snake’.
This entailed us forming a long line where each person has to copy what the person in front of them does, with everyone getting a turn to be the leader (head of the snake).
From jogging to star jumps, wriggling our hips and performing strange dance moves, we all laughed ourselves silly as we snaked around doing ridiculous things. Next up was an intuitive body sculpture where each person used their body to represent how they were before the course and how they were at that moment (mid-course).
The lecture began with a review of making compost, after which we discussed water. A small demonstration showed us how water always takes the shape of the container which it is in. We also learnt that dew is always more powerful than normal water. The origination of water and its cycles concluded our discussion, and we headed outside to learn how to create an A-frame.
To understand why we create an A-frame, it’s first necessary to understand what a swale is.
What is a swale?
Simply put, a swale is a horizontal ditch that follows the contour of the land and traps water (like an underground water reservoir).
Basically what happens is that when it rains heavily, water tends to run off the land. A swale arrests its progress so that the water soaks into the soil like a sponge.
Properly designed, swales allow extra water from heavy rainfall to slowly run off without causing erosion/gully formation. Creating multiple swales, in turn allows the overflow to be captured downslope as well.
What’s more, swales collect eroded soil and mulches, creating rich, moist soil which can be used to grow water-loving plants. Swales also create high-moisture microclimates, useful for growing a diverse range of useful and edible plants.
An A-frame effectively marks the contours of the land, so you can decide where to dig your swale.
Literally forming the shape of an ‘A’, the A-frame has two legs equal at approx 1.5 metres long and a 1 metre long cross bar. A line with a weight hangs off their intersection.
The cross bar, attached at the same point on each leg, is marked at its centre. When the weighted string (plumb line) cuts the centre mark, the two legs are at exactly the same height.
We divide into groups and get started.
What materials are needed to create a A-frame?
• Two lengths of wood approx 1.5 metres long
• One length of wood 1 metre long for the cross bar wire as well as bolts with wing nuts
• A length of string long enough to fall from the top of the A to below the cross bar
• A weight such as a stone
• A sharp knife and pencil
First we measure and mark 30 cm from the bottom of our two wooden poles, and then connect them to form an A-shape.
Then we attach the cross bar at the 30 cm mark, with wires or bolts and wing nuts.
We then tie the string to the top of the A -shape, allowing it to hang below the crossbar, and attach the weight.
Marking the centre point
Although we can simply use a measuring tape to mark the centre point, it’s useful to know how to find the centre point, using only the tools we have.
Still in our group of three, we place the A-frame on a sloping surface. Where the string stabilises at, one makes a mark on crossbar. We turn the A-frame around in exactly the same spot and mark the crossbar again at the stabilisation point.
Taking a separate piece of string the length between the two marks we have just made, we fold the string in half, placing it at one mark and where it ends, we make a notch with a knife. This indicates the centre mark.
Should the string with the weight attached to it fall exactly on the centre mark when the A-frame is placed on the ground, it means that each point of the A-frame is level.
Marking the contour with an A-frame
After building the A-frame with a marker and drill, we use it to walk across the land, shifting the moved leg up or down the slope until the weighted string stabilises at the centre mark.
We then mark that point and swivel the other leg around, repeating the levelling, marking the contour with a line of pegs (or rocks). The weighted string (plumb line) often swings like an out-of-control pendulum and can take a long time to settle. However, our 3-man team manages with one of us steadying it at the bottom.
Our fun with the A-frame ends with a quick practical exercise where we split into teams to discuss how we’d most effectively capture water. Our assignment was to find ways of capturing runoff from the roof of the chicken coop.
We decided to make a ditch which would direct water flow into our swale, putting rocks at the bottom to reduce erosion and runoff. We’d also plant banana trees in the areas where the most rain comes down.
After a lunch of tomato soup and homemade bread, I wandered to the river's edge to read in the blissful quiet.
We then learnt a bit more about swales, before going to dig one.
As I mentioned earlier in this blog article, a swale is a ditch which follows the contours of the land to either redirect or capture water. A swale is generally one spade wide, and two spades deep. The steeper the slope, the deeper the swale.
Avice shows us how to dig the swale, starting with turf removal. This entails cutting into the turf with a spade, before sliding the blade underneath to lift it, giving us a straight edge.
We then invert the turf and pile the rest of the soil on top. Our soil has a high proportion of clay and loads of stones, which makes digging very difficult.
We then pat down the edges of the swale to give it some form and strength until the plants and dynamic accumulators have established their roots in order to take over the role of holding the soil together.
After a few hours have passed in the scorching sun, suddenly the idea of using a machine to dig the swale, such as a grader or disc plow, seems much more attractive!
Suddenly it's tea time and dirty, tired but not defeated, we leave our hard work behind us to go wash up before tea. I’m enlisted with the task of making a salad for dinner, using anything I can find in the garden.
My mom and I go foraging, finding spinach, romaine lettuce, basil, mint, and thyme to form our base, with cherry tomatoes, avocado and fresh corn tossed in a large bowl.
Dinner is a barbeque over the river. We cook up a butternut, some potato and have it with our divine salad while everyone else eats salad and fresh fish. It’s another delicious meal to reward our hard day’s work.
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