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David Wood

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since Oct 07, 2014
Sth Gippsland and Melbourne
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Recent posts by David Wood

I don't follow the logic of not wanting to use a post when a tree is handy. As discussed above, using living trees as fence posts to hold nails, staples or wire is poor design with respect to several factors.

Using living trees as hedges has some appeal but takes a while and once they've grown into a hedge it's difficult to see through them to what's going on in the next paddock. Live hedges are also liable to be colonised by wild mammals which may or may not be a good outcome. Foxes and rabbits like a bit of cover, for example.

Wattle fences can be useful for some livestock but are labour intensive to make and also lack see-through-ability.

I'd like to have a crack at pleaching to see how strong it can be but I don't have any data at the moment.

WRT sustainability, in my opinion a good solution is post and rail using durable timbers. In Australia, this might be a Class 1 or 2 inground durability timber for the posts and a Class 2 above-ground for the rails. But this is labour and materials expensive and while it will hold cattle and horses a fence of this nature may struggle with sheep, lambs and small calves. Putting an electrified wire at an appropriate height will help with this.

My understanding is that in traditional agricultural systems in Europe it was common to have someone handy to keep an eye on them for much of the time. So if animals did get through a pre-wire fence this could be dealt with before major damage to a crop etc But with labour costs under our current economic system it makes more sense to have a stronger fence. And can you see anyone these days showing a lot of interest in spending day-in, day-out keeping an eye on a herd of sheep?

You could try making a list of the objectives you're are trying to meet, prioritise them and then make a list of possible solutions with pros and cons. Match these up and a feasible, acceptable solution should become apparent.

On a related note, I think a more structured design approach would help in a lot of areas in sustainability but that's another topic

Hope this helps


2 years ago
And if you plan to use nails or staples to hold wire to the tree, these holes can let various pathogens, insects etc into the tree
2 years ago
I've never heard of anyone planting trees at 30cm separation with the intention of doing something useful with them for posts, timber etc. Maybe as fodder but that would be an expensive process using seedlings as against seed.

There's a project in NZ looking at growing durable species for posts to replace treated pine:

and there's some publications on work done in NZ on this topic. See, for example:

They're talking about planting at up to a few thousand stems per hectare so several metres between stems.

We've planted a load of durable species at about 600 stems/hectare with a longer rotation planned. We will probably try some denser planting with the aim of a relatively short rotation for posts.

2 years ago
Sounds like a great project. A few comments:

- Your spacing calculation adds up to 30' by my calculation if I read what you are proposing correctly. Not sure why Barry thinks your spacing calculation is incorrect.

- Having a 5' gap to the fences from the first and third row means that stock will have trouble reaching the stems. As the trees grow in the outer rows you will have to trim branches that point towards the fence until any such branches are above the reach of stock. Otherwise they'll eat the branches which can also cause damage the stems. Cattle are big animals and can give a fair old wrench to a tree or shrub if  they can get their teeth onto it.

- The rows closest to the respective fences will also be able to take advantage of what is sometimes called edge effect by getting their roots out into the soil on the other side of the fence for extra water and nutrition.  I've seen close planted bluegum (Eucalyptus globulus) in a shelter belt that were doing well but they were visibly pushing their roots out 10m into the surrounding dirt. And because there is less shading on the fence side from other trees the tree may develop a bushier habit than might otherwise be the case which means more canopy and hence better growth. But this also complicates growing the trees for timber if that is the aim as the stem will be knottier.

- A 10' gap to the interior row and the close spacing between trees in this row will see the trees in competition for water and nutrients quite quickly. This will adversely affect growth from a relatively young age unless you plan to thin. But close spacing does push trees up which improves form for timber without requiring lift pruning.

What are your objectives with the trees? Do you plant to harvest any for timber? Or are they purely for habitat/food/shelter?

If you do plan to harvest for timber, it would be worth checking the markets for hemlock as while I'm not familiar with US timber markets I do recall that at least some hemlock doesn't attract good prices. And if you can get improved seed provenances for any trees with timber as an objective this can help with growth rates and form

Hope this was helpful

2 years ago
As well as eucalypts endemic to tropical and sub-tropical areas, there's a wide rage of eucalypts that grow in temperate areas in southern Australia including Tasmania. Some of these grow in areas where they will be exposed to snow. For example, Alpine ash (E. delegatensis) and Snow Gum (E. pauciflora). Many of the temperate species will cope with below freezing for greater or lesser periods - typically overnight - once established. We lost quite a few Corymbia maculata (Spotted Gum) seedlings in an exposed site to a particularly cold night with a gale blowing a few years ago. (Corymbias used to be part of Eucalyptus but were moved a few years ago.) We have other established Spotted Gum that survived those conditions.

This reference has good information on eucs and other Australian species:

There's some good information on growing species out of their normal range at:

Pollarding is generally used to mean cutting the tree back above browsing height so the new stems are not nibbled by opportunistic browsers such as rabbits and deer.



eric koperek wrote:TO: Cesca Beamish
FROM: Eric Koperek =
SUBJECT: Growing Eucalyptus trees in England
DATE: Pm 7:38 Tuesday 21 June 2016

(1) Just a word of caution: Be certain that you are really growing "Eucalyptus" trees = Botanical Genus EUCALYPTUS as in Eucalyptus globulus variety globulus = one of many varieties of "blue gum" distilled to produce medicinal eucalyptus oil. I do not know of any Eucalyptus species that grow where it snows. Eucalyptus trees are tropical or sub-tropical. They do not tolerate hard freezes. How you can grow Eucalyptus in England is a wonder of forestry.


end comment

2 years ago
If you're defining cover crops to just mean crops used over winter then no arguments that they are unlikely to add a lot of nitrogen. Sounds like we're in agreement that legumes used as fodder crops or in a rotation add useful quantities of nitrogen.

I don't understand why you're clearing large areas of forest to make cropland as I don't see how that can be regarded as sustainable or how it fits into permaculture. If it's reforested former farmland IMO a much better use would be to use it for timber. Clearing forest for farmland is what we used to do when there were vast untapped wildernesses and we didn't care about trashing land as we could always move on to virgin land. Those days are over.

As for the nitrogen deficiency you're seeing after cutting down the trees, if it's reforested abandoned former farmland - which is common in the US NE - a useful soil test would be to check for nitrogen before you cut down the trees. From what you describe, I suspect you'll find that the soils were low nitrogen before you cleared. Agriculture generally takes a lot of nutrients out of soil. Swidden agriculture recognises this by only farming for a few years after clearing the trees. If you want high outputs consistently out of a piece of land over many years you'll generally need high inputs. And how to achieve that sustainably is perhaps the major challenge for agroecology approaches to agriculture.
3 years ago

Travis Johnson wrote:All trees are nitrogen fixing to some degree as well as nitrogen robbing. It really is a cycle, not a one time fix all.

In hardwoods, they drop their leaves every year, while with softwood they self prune their branches. As these fall to their base anything under 2 inches in diameter, within two feet of the ground, within two years will decay, at least in New England where I live anyway. This ultimately ROBS the soil of nitrogen as it breaks down that woody mass.

While nitrogen drawdown is a widely held belief there's very little evidence from any studies of this actually occurring. There may be some small effect right at the interface between the rotting material and the soil but that's about it both from what I've observed and what I've read in various published studies.

Travis Johnson wrote:
After a bit of time however, about 7 years, that process changes and the nitrogen is released.

Most of the nitrogen in arboreal above ground biomass is in the leaves, bark and new growth. This material rots quickly in a damp environment and the nitrogen either volatilises or is incorporated into the biota. I'm not aware of any significant long-term nitrogen recycling mechanisms from larger material. Carbon, on the other hand, definitely takes part in longer term recycling pathways particularly from larger material.

Travis Johnson wrote:
Cover crops are almost impossible to compare to hugel construction because they really are apple and oranges. I use cover crops on my farm, but the amount of nitrogen fixing they do is very slight compared to hugel construction simply because their lifespan is so short. I use them more for erosion control than fertilizer. It definitely is not enough to grow a high yielding crop on. With hugels (using wood) you do not have that issue, they are self-fertilized by definition since they use so much nitrogen-laden mass.

Legume crops are an excellent, quick way to fix substantial quantities of atmospheric nitrogen and to make this available to other plants and soil biota. Do you have any references for how hugel can do something similar? It sounds unlikely to me.

3 years ago
We have about 60m fall on our block with several creeks. I'm thinking about installing a hydraulic ram:

to take water from the creek to pump up the slope a bit into dams and stock watering tanks. I've found a few hydraulic rams for sale online. I would be very interested in any lessons learnt from using this technology.
3 years ago

Alder Burns wrote:People do what they've got to do. Perhaps the hillside is the only land they could afford, without moving far away. The challenge of permaculture is often how to make the best of a less than ideal situation. Yes, hillsides beyond a certain degree of slope are best left in forest, but "what if"?

So their only option in life is to engage in clearly unsustainable activities? Which IMO are extremely likely to cause severe damage to their block which can take centuries to repair. As well as with a bad slip wiping out the road below them and possibly damaging the land of neighbours down the slope. I just don't see how that's justifiable. If they can't afford to buy a block that's suited to agriculture or they don't have the expertise to properly farm on slopes - good quality terracing is very high input but can with maintenance can last for millennia - perhaps they should choose other activities.

There's a relevant expression about wrapping yourself in the flag. Politicians will often justify some course of action by claiming they're more patriotic than someone with an opposing view. Just because this couple think they're doing something with a light footprint doesn't mean this is the case.

Because a lot of people watching this show may not have the experience to critically review there's a real danger that viewers will think this is sustainable behaviour.

3 years ago
There's a large hayshed on our block with a metal roof about 20m x 10m. We get around 900mm to 1400mm annual rainfall.

There's currently a 23kl tank connected to the guttering on the shed. I'm thinking about adding another 23kl tank next to the existing tank and also putting a 50kl tank on a rise about 70m linear and 5m or so vertical above the current tanks.

The 50kl tank would be at the high point of a paddock so could be used to drip irrigate anything in there by gravity. I'd like to reticulate water to this larger tank from the tanks by the hayshed using a submersible solar pump. I'd be very interested if anyone has experience and lessons learnt with using a solar pump in this fashion. Particularly how often the solar submersible needs to be checked and what goes wrong.

I'd like to use water from the smaller tanks to irrigate young trees and crops in a lower paddock. From a bit of reading it seems I can use a hand trigger rose or a few sprinklers supplied by a small electric pump. Power would be from batteries or a small generator at the hayshed. (We're offgrid.)

Again, I would be very interested in any experience with using small electric pumps off tanks to supply sprinklers and the like


3 years ago