Archive for October, 2009

PDC…..Week 8

October 28, 2009

This week we looked at trees and forests and the benefits they provide. Forest edge species buffer the wind, collect nutrients and support a greater diversity of wildlife than the forest itself; it’s important to retain those edges. Trees cool the air (by evaporation) and warm it (by condensation).  Of the rainfall that hits a forest, 25% is evaporated from leaf surfaces, 50% is returned to the atmosphere by transpiration and 25% leaves as groundwater runoff. That means 75% is returned to the air. Inland rain occurs primarily because of forest transpiration. Remove the trees and the rain goes too; something humans with chainsaws don’t seem to have woken up to yet.

We looked at windbreaks and shelterbelts and how to design them. We learned how to assess the wind strength and direction at a site simply by observing the shape of the trees.

We discussed agroforestry and began with a pertinent quote from David Holmgren: “In a low energy future, the wealth of nations will be measured by the quality and quantity of their forests”. Yes, well. I can see there will be a lot of poor nations in the future (think: Saudi Arabia; no more oil; no trees; lots of desert; not a good future for them).

Agroforestry isn’t about growing acres and acres of the same tree species. An agroforestry system should aim for a diversity of species and ages, so that a varied yield is obtained over time. Timber trees, fodder trees, honey production, wildlife habitat, fuel, fibre, nuts. These are some of the beneficial products of a diverse system.

Out into the garden and we learned how to coppice and pollard trees and how and when to prune for timber production; a nice straight  trunk being the desired, valuable  end product.

I learned quite a bit about firewood (important, as we have a slow combustion heater). You want trees that grow fast and burn hot when young. Black Wattle and Casuarina are excellent. Generally, the heavier it is the hotter it burns. If you have a larger property, with some native bush (as we have), then general thinnings and prunings will provide most of your needs without a specific woodlot required. (We’ve been on our bush block for 10 years now and have never needed to buy firewood).

Another tip: leave cut firewood in lengths of 1.5 metres and stand them upright against a tree trunk or fence for a couple of months. The sap drains out much faster and they dry quicker (I always wondered why people did that!). Coppiced trees are ideal because they produce many new branches from the stump and these can be cut at 150 cm diameter and don’t need to be split. If you do have to split wood, it’s much easier when it’s still green.

After lunch we visited the sites for our final design project for the course. There were two options—a 5 acre hobby farm and a local community garden. I opted for the garden, believing it would provide an opportunity to showcase permaculture, plus having the potential for some varied design concepts. Over the last 5 weeks of the course we’ll spend increasing amounts of time on completing our designs and finally presenting them.

So it’s on the downslope now. I’ll be sorry when the course ends. I’m enjoying it immensely.

PDC…..Week 7

October 20, 2009

Half-way there and still much learning taking place.

This week we looked at water—fresh water, greywater and blackwater. Strategies for re-using greywater: regulate what goes down the sink (“only put down the sink what you’d be willing to put on your skin” [Wendy van Dok]; don’t store greywater for more than 24 hours—this is required by law—pathogenic bacteria can breed up if it is left for longer; avoid contact—by law, greywater can only be applied by sub-surface irrigation; be aware of quantities—the most common problem in using greywater is waterlogging. Share it around, don’t leave it running on the same area for weeks. All common sense really.

Greywater treatment systems can be an expensive option. Far better is to create an artificial wetland—a reed bed system. Bacteria on the roots of the reeds filter the greywater and the reeds can be regularly cut for mulch or compost. Greywater mulch pits are even better—greywater is diverted into a slotted drainage pipe which is placed inside  a hole filled with mulch. The mulch eventually rots down and can be placed around fruit trees and the pit refilled with fresh mulch. The idea I liked was that a long narrow hole filled with mulch can double as a pathway.

Good link here.

The easiest way to deal with blackwater is to install a composting toilet. We discussed various types. The best resource for this is the Humanure Handbook, which is now online.

Finally we looked at collecting and storing fresh water; the 3 S’s: slow, store & soak. Don’t let good water run off a property; slow it down, store it and let it soak into the soil. We looked at tanks (make them multifunctional—use a tank to screen out neighbours, or grow a passionfruit over it). Swales—level trenches dug on contour—can intercept water running over the land and store it so it leaches slowly into the soil. We learned to mark out the contours using three pieces of equipment—an ‘A’ frame, a length of plastic tubing filled with water and attached to a couple of measuring posts (called a ‘bunyip’) and  (the most sophisticated of all) a laser level. This bit of practical work out in the property’s sloping driveway, caused much hilarity, not to mention enjoyment, as we checked our measurements with A frame and bunyip against the laser level and found them spot on.

We looked at building various types of dams—constructing, maintaining and fixing leaks. We went into (not literally) natural swimming pools and wetlands, french drains and rainwater gardens, basins and erosion prevention. There was just too much to go into here.

I had previously thought the day we spent on soil was the most fascinating, but this one on water just boggled the mind. All the way home in the car, my brain hummed with ideas.

PDC…..Week 6

October 12, 2009

This week’s PDC course focussed on preparing a design for a permaculture system on the property we had visited last week. This was to be our first serious attempt at design.

Our four groups settled themselves down in various parts of the house and with coloured pencils, rulers and rubbers (the latter, we discovered, a very important tool for beginners!), we set to work. The first thing to do was to draw a (reasonably) accurate scale plan of the property showing the location of the house and other important features. Our architect member, Paul (not in the sub-group I was in, unfortunately), had already produced a very professional computer-generated plan and had taken many photos on the day, so everyone was to-ing and fro-ing to his group to remind themselves of features they hadn’t taken note of. The forgetful ones, who had omitted to take proper measurements (or perhaps should I say, inspired ones—me included), had produced colour aerial shots of the property complete with measurements (thank you, Google Earth!).

After much discussion and many rough sketches we were ready to transfer our final design to the ‘best’ paper. I think our group did a pretty good job. We had ‘removed’ a huge evergreen tree in the back garden, which allowed more winter sun into the property. We kept another huge oak tree in the front garden because it was deciduous and let winter sun in anyway and also provided valuable oak leaves for composting and mulch. We’d established blueberries (which like an acid soil) under it, along with redcurrants, which will tolerate some shade. We’d put a grapevine over the patio and planted cut-and-come-again vegetable beds alongside the patio, so there was quick access to these from the nearby kitchen. As the overall garden area was small (large 2-storey house on an average-sized block), we made use of fences for fruiting vines and espaliered fruit trees.

We added a water tank in the back garden (the owners had just installed a 10,000 litre tank in the front garden) and covered it with a passionfruit vine. We built a greenhouse next to the tank and the run-off from its roof went into the tank.

Our ‘piece-de-resistance’ (so we thought) was the chookhouse and yard. We put this in a narrow section of garden between a covered side passageway and the side fence, such that the back of the nesting boxes opened onto the passageway, which was just outside the laundry door. So the owner could collect eggs from within the passageway, without going out into the weather. The chookyard run was extended right to the orchard in the front corner of the property, so that the chooks could forage under the fruit trees and fertilise them at the same time. Next to the chookhouse we placed the compost bin and worm farm, again accessible from under the cover of the walkway and close to the laundry door. After a slightly stressed period in which we thought we weren’t going to be ready in time, we finished our design and adjourned for another of Jessie’s super-tasty lunches.

After lunch, each group presented its design to the others. Cam (our teacher) made valuable comments and suggestions. All in all, I found it a very satisfying introduction to the ins and outs of permaculture design.

PDC…..Week 5

October 4, 2009

No doubt about it—this course gets better and better and more fascinating by the week.

We began with a short introduction to microclimates—how to manipulate factors on a site to create mini climate zones to better facilitate the growth of plants. Strategies such as white walls or light-foliaged plants to reflect light, dark surfaces (walls, rocks) to trap warmth, plus using evaporation, condensation and humidity; there seem to be endless possibilities to play with existing site conditions. A classic example is the north-facing suntrap, a semicircle of light-reflecting plants encircling the plants whose growth is to be enhanced. A water feature in front can further add to light reflection and store warmth. It was interesting to learn that this type of structure can allow plants to be grown from the next climate zone, e.g. subtropical plants could be grown in Victoria.

On to strategies for urban design and an opportunity to do our first real design. Cam had arranged for us to visit a neighbouring property where we were to actually do this. The owners were out for the day so Cam & Jessie became ‘pretend’ owners. They told us what they wanted to achieve for the garden and we learned the right questions to ask. We walked the property, taking measurements, noting features and coming up with ideas (“hey, this would be a great place for the chickens!”),  then returned to home base and began preparing sketch plans of the property with (hopefully) all the necessary elements beautifully integrated into a good permaculture design. We had split into four groups, so there will be four separate designs to consider when it’s all over. Should be interesting to see and compare the variations!