Archive for the ‘Groundworks’ Category

Greenhouse grow dome

Sunday, July 23rd, 2017

Why would anyone need a greenhouse in Portugal? Given adequate water and soil fertility, the climate provides more or less ideal growing conditions pretty much year round. General climatic conditions though are one thing. Specific microclimates are another. This quinta has mountain ridges to the south and west and doesn’t get much heat from the sun early in the year. As a result, the clay soils are slow to warm in Spring. Any summer vegetable planted out much before May tends to stand still and then take a while to get going again once soil temperatures rise, so peppers and aubergines frequently don’t get harvested until October and November. A greenhouse in the sunniest spot on the quinta would make a huge difference. I could grow plants from seed in early Spring, bring them on while the soils warm up, and overwinter those which can be effectively perennialised for an early start the following Spring.

I also wanted to experiment with aquaponics to find a way of growing vegetables intensively without the need for supplemental irrigation.

The completion of the geodesic dome greenhouse was consequently eagerly anticipated. The covers went on at the end of April. Seeds were sown and plantings made. And since then, I’ve been revising my ideas of how growing our food here can be achieved almost as fast as the plants themselves have been growing.

Geodesic dome greenhouse covers installed, end of April 2017

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Geodome greenhouse progress

Monday, May 22nd, 2017

Projects here seem to have their own timing. What seem like frustrating delays at the time have an uncanny knack of turning out to be necessary pauses: intervals which allow for much better solutions to emerge. The geodome greenhouse has been no exception. With the groundwork complete by the middle of last summer, I was hoping to have it covered in time for winter. This wasn’t to be. My fault mostly. I wasn’t happy with the lack of solid UV resistance data and guarantees on clear PVC and went off to ferret out something more robust. Several lengthy explorations into such materials as ETFE and polycarbonate later, it was clear that robust was beyond budget-busting, so in the end I came full circle back to the PVC.

But during the delay, two things happened. One of the suppliers we were in contact with listed a new high transparency UV-treated PVC film. And Liam acquired a high-frequency PVC welder. I’m sure neither of these facts will mean much to many, but take it from me: the end result is just so much better than it would have been had neither of those two things happened.

The greenhouse cover is now almost complete!

The PVC cover goes onto the geodome greenhouse

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Duck ponds

Sunday, May 15th, 2016

With the building of a duck house, there had to be a duck pond to go with it. or, as it happened, two duck ponds.

In addition to being ponds for ducks, these ponds also form part of the general water-retention strategy for the quinta. The aim is to slow the passage of water through this steep land and spread it as far as possible from the stream, allowing it to infiltrate and hydrate the soils. This promotes the growth of the vegetation which is so essential in improving the soils here. Vegetation decomposes to provide soil carbon. Without soil carbon, these thin soils haven’t a hope of holding onto moisture (or much of their biota) through the hot dry summer months. Irrigation becomes necessary. But build up soil carbon levels enough and eventually irrigation needs are minimal, even zero. So in order to make irrigation unnecessary, it’s initially necessary (at least if any kind of speed is required).

Back to the duck ponds. Or maybe duck puddles would be more accurate. They’re barely large enough to be worthy of the word pond, though they’re more than adequate to keep a couple of ducks happy.

Inlet for the second duck pond

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Ponds four years on

Thursday, May 12th, 2016

It’s been quite a saga, this business of creating unlined ponds. I particularly wanted unlined ponds, because their principal purpose is to provide hydration for their surroundings in the course of slowing the passage of water through the quinta. But as I’ve learned, it takes a while for them to stabilise. There are six of them; two sets of two on the top and bottom terraces above and below the yurt terrace, and another pair of very small duck ponds on the bottom terrace. Small ponds – which these all are due to limitations of terrace width and slope – are much more sensitive to small perturbations.

Spillway between the ponds on the bottom terrace

Spillway between the ponds on the bottom terrace

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Subterranean heating & cooling system

Wednesday, May 11th, 2016

The previous post on the geodesic dome greenhouse outlined the logic in choosing a dome for this site and how it was by far the better option for fitting in all the things I wanted to have in this greenhouse. These include an aquaponics system and a bathroom as well as growing space for tropical and frost-tender fruits and vegetables, seed growing areas, a rocket-stove water heater and a worm farm – a fair bit to cram into an area measuring just 7x5m at the outset.

Geodesic dome greenhouse frame

I also wanted to build in a subterranean heating & cooling system (SHCS) to make even better use of all the thermal mass present in the solid bedrock floor and back wall. This is a proven low-tech solution for maintaining comfortable temperatures and humidity levels in the greenhouse year round. It can minimise or even eliminate the need for supplementary heating or cooling.

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Geodesic dome greenhouse

Sunday, May 8th, 2016

Back in July 2012 we dug a chunk out of the mountainside in preparation for a ferrocement rainwater harvesting tank. Plans for the tank were later shelved due to budget constraints, but a good use for the site was never in doubt. It’s one of the few parts of the quinta to have sun at winter solstice, so was perfect for a greenhouse.

Geodesic dome greenhouse site

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Swaleage

Monday, August 3rd, 2015

It’s been a long time since this blog was last updated. Those keeping up with us on Facebook will have some inkling of what’s been going on at the quinta in the meantime, but I’ve failed dismally at getting to the more detailed documentation of it all. Mostly a case of too busy doing the doing to be reporting the doing …

Following the successful implementation of a swale system on the bottom terrace last year, this last Spring I put in a similar system on the terrace above it. It’s a narrow terrace with very similar problems to the one below it – soil so dry in summer it barely supported a few fruit trees (which consequently dropped most of their fruit before it got anywhere near ripe) amongst grasses and wildflowers which would be dry and dead by July. In summer, the soil turned to dust in your hand and blew away.

Mid fruit terrace

The terrace when we first saw the quinta in November 2008 – a few neglected fruit trees and a lot of encroaching bracken

Mid fruit terrace

The same terrace in May last year – a few more fruit trees, a lot less bracken, but still a largely barren terrace

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Swales

Tuesday, November 11th, 2014

Swales – level ditches dug to follow the contours of the land – are one of the principal ingredients of permaculture earthworks which are, by and large, recipes for catching and holding rainwater runoff and encouraging it to slowly infiltrate the soil rather than being lost to the nearest river. Because they’re level, swales don’t channel the water away but hold it in situ until it soaks into the soil. They can be dug to any sort of scale and used alone or, as part of an integrated water catchment system over an entire property, in combination with other elements like ponds, infiltration basins and dams.

Bottom ponds

On narrow terraces and steep mountain slopes with thin soils – ie. here – swales are not something you can use on a large scale, but they can still be useful. When I dug the lower ponds, the effect on the ability of the surrounding soil to support abundant growth was immediate and impressive, but it didn’t extend too far along the terrace. Just 2 metres away the soil was so dry in summer it barely supported a few grasses and wildflowers and would turn to dust in your hand and blow away. So after working out the contours of the terrace, I decided to extend the area of hydration much further along by using the ponds to feed small swales.

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Waterworks completed

Thursday, May 1st, 2014

Among many other projects on the go simultaneously last summer was the installation of some water storage capacity and supply lines to the various buildings on the quinta. The design and layout gives a good head of gravity-fed water to all parts of the quinta, and provides buffering for the vagaries of daily stream flow in late summer. The two tanks constructed from pre-cast concrete rings were fairly quick to construct. Finishing them proved more of a problem.

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Timber-framed grey water-processing greenhouse – part 2

Friday, February 14th, 2014

The last post on this build finished with the laying of the chestnut ring beam which forms the base of this sweet chestnut timber frame construction. The next part was to raise the main supporting structure.

Splitting out braces with a small axe

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