Tuesday, 7 February 2012

Digging A Small Swale

Towards the end of last week I posed an open question to the awesome folks on the open-source social network Diaspora*, asking if anyone could think of a good way to visualise the relationships of beneficial/detrimental interactions between various plants. If we can figure that out, it might make my job of deciding how to arrange the smaller shrubby plants a lot easier, and similarly make it easier for anyone in future.
While I got a friendly response but didn't get any answers to the question itself that night, I updated my map in more detail, noting a few places where I thought various crops ought to be planted just as a draft, using freely-available information on companion planting available online, such as Wikipedia's List of Companion Plants, which unlike some of the other lists, is more likely to evolve over time.
Extra zoomed section on the left has a key along its left border.

I've had some thoughts since then, that maybe we could write a cloud-computing puzzle game, where players have to arrange plants on the ground (perhaps on a grid such as in the cute 2D game "Plants vs Zombies", only without the graveyard zombies), so that they get the best yields and ecological stability, counting the time/energy expended on things like earthworks, and perhaps calculating a score from that at the end. I imagine it having a learning curve of complexity where you start with small flat-ground puzzles and add elements like sun/shade, slope, wind, rain, soil type, etc.
The game could share results/scores like the Foldit cloud-computing program, over the web to server(s) hosting such highscores, using humanity's great capacity for lateral thinking to supply novel solutions to these problems to future permaculture designers. This is probably a tangent to be developed in conversation elsewhere though.

Sadly, the next day those bare-root fruit trees didn't turn up in the mail, so the fedex service used by mail-order trees kinda let us down a bit. Not having the trees to plant did give me a chance to start digging a water-harvesting swale, although planting them wouldn't have taken very long anyway, since I already had the holes pre-dug and covered over. (Since I got back to Glasgow, my friend told me that the trees didn't arrive until Monday, so I'm a little concerned about their health now.)
I brought something with me that I've learned should turn out useful after disturbing the soil.
Queue music.
So, I set about digging a swale just below the contour line that we had measured out, to give a good supply of water to the fruit trees where they will be below the swale.
Digging a water-harvesting swale is a fairly simple task once you have your line marked, where you have loose soil you can just shovel the earth up into a mound on the lower side, in this case where there were lots of tough grass roots, my approach was to repeatedly cut out blocks of sod in a long row, and flip them over to the lower side, on top of the grass to kill it down.
I started in the middle and worked my way east. One block is a start.
It was simple to start with anyway, but sometimes when digging in this highland soil, you find boulders...
...and they get right in the way of the fork & spade.

I dug along some more, went for a brew, and came back to pick up where I left; thinking I'd had quite enough of boulders for one day, I came across another one even more awkward than the first.
A wild boulder appeared!
I ran the swale off to the east end of the contour that we measured, and then turned it back slightly towards the hill, so that there was a cut-off and water couldn't get out there.
Extra soil mounded up to reinforce this point.
I had a closer look at that boulder, and it looks to be quite a big problem, since it could restrict water from passing by it along the swale. I did my best to dig around it a bit, but it was just too big in exactly the location that I wanted to put my swale, so I just hope that any significant water that gets in there will slosh over it.

I went back to where I started, just east of the bit I intended to be wide and slightly pond-like, and started to dig that out, heading north.
Here's the pond half-- oh wait you can't see that can you? I could.
Digging by moonlight (like a boss).
Again, with flash, the pond-like bit half-finished, with some more swale already dug further north.
Now with only moonlight left, since my friend was away at work all day and digging by yourself can take a while, I mounded all the earth in the wide section into a double-thick wall on the lower side, and ran the swale off to the fenceline.
Once there, I wanted to install a level-sill spillway so that if the swale was to fill up during a long rain event, any excess of water could be allowed to empty out passively by one side, without causing any soil erosion. Since I know that the fenceposts there are cast out of concrete with a big lump at the bottom as an anchor, I decided to bring the swale wall up against one of those posts, where the hard top of the concrete anchor would make a perfect run-off surface, even though I reckon that damn grass will survive almost any water thrown at it.
This part of the swale wall I piled up a little higher than normal and actually packed down tighter with my boot, so that it could withstand some water flowing past it.
I don't expect monsoon-type rains any time soon, but it's better to be safe.

As for the contents of the mystery jar, that was a mix of manure, water and pigeon/gungo peas, to repair the soil that had just been worked, fix nitrogen into it by growing in symbiosis with some of the beneficial root bacteria that I mentioned in my last post, and act as a cover crop to some extent so that the grass shouldn't take over again right away. I emptied them out thinly along the swale wall, and with any luck they should germinate in the warmer weather in the coming week and fix the soil until I get back to plant more veg.
Gungo peas, aka pigeon peas, a useful soil-repair legume.
I've had those peas from a big sackful for quite a while now, so I don't know if many will germinate, and then I don't know how long the warmer weather that came over as I was leaving will last for (this is probably better done in autumn), so any that do germinate might not last long, but something is better than nothing. I'll just have to wait a few weeks til I go back to sow seeds, to see the results of this bit of earth-surgery after the weather has affected it without my intervention.
How the ditch looked the next morning as a small rainstorm was blowing over (least-shaky picture I took)
I haven't measured it exactly yet, but from looking at the sketched contour, I guess the curve of the swale to be about 20-30m long, while the blocks I was taking out were for the most part 1-foot-cubes (30cm ^3) and a couple of points were wider, up to 4x that width, I estimate this swale is probably capable of holding something like 80-120 cubic feet of water while it drains into the landscape. Given the hilltop location and that the weather is usually quite steadily cold&wet but not often heavily rainy, there shouldn't ever be enough rainwater in one go to break the swale wall, but then that's partly why we want it there, to trap whatever bit of water falls on that hilltop.

If you'd like a good video tutorial on this sort of installation, check out "Harvesting Water The Permaculture Way" where Geoff Lawton took a bunch of permaculture students onto someone's land in Australia to install a rainwater-harvesting system about 10x the size of this one, including a dam. In that scenario they brought in the fancy surveying gear that I mentioned in my previous post, along with a backhoe excavator-tractor. I largely developed my methods from that video, scaling the example down to this situation appropriately. As was mentioned in that video, things don't always go exactly to plan once you start digging, and in this case the very rocky ground posed an interesting problem.

On a cheerful recycling sidenote, here's a little something I'll be testing soon when I sow spring crops, an alternate method to the early indoor sowing and later transplanting that is often advised in gardening. Some people might use 'cold frames' or big sheets of plastic to try and keep delicate plants warm while they get a little extra sunlight for an early crop, but this is my way of creating a temporary mini-greenhouse for them...

First, take a couple of empty soda-bottles:
If you had some nasty sugary stuff in them, wash them out first, and stop drinking that stuff.
Next, remove the labels and slice each bottle in a hoop around its centreline.
You can use either end of the bottle for this, and sturdy tent-pegs; I just used twigs for quick demonstration purposes.
Poke holes slightly back from the cut edge to push pegs through, you decide how many you want depending on how windy it is, and secure one of these over wherever you have sown seed for a vulnerable plant. You want the bottle that you use to be large enough to last until cold weather passes.

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