"George.com" wrote in message
...
Interesting book I and 3/4 the way through, Collapse - How societies
choose
to fail or succeed, Jared Diamond (I can recomend it). There is a chapter
on
Aus that is good reading. The chapter is titled "Mining Australia" and
says
essentially that for decades ockers have mined not only minerals but also
soil nutrients, timber resources, moisture/water and fishing stocks.

It is exactly the same in any other western country which is rich in
"natural resources". The only difference between Oz and other western
countries is that Oz has a (generally) extremely fragile soil and being a
very old continent, limited fertility except for thin coastal strips.

The bit about timber I found expecially interesting. I am aware that Aus
exports timber, we get oz hardwood in NZ for decks and the like. I
presumed
that it was from a sustainable resource. According to Diamond this is not
the case. The rate of timber growth is slow for you compared to say NZ.
Once
a forest is stripped of mature trees the conditions for regrowth is quite
difficult and can lead to the drying out, even desertification, of the
soil.
Not sure I will buy any more Aus hardwood if that is the case.

Without reading the book, it is impossible to know what he's writing about
or which areas of Oz he is writing about. I presume he may be writing about
old growth forests. What is happening in the destruction of old growth
forests in several of our States is simply criminal IMHO. As is the spread
of Pinus radiata into our much of our fertile farming lands.

He reckoned that much of the nutrient value of your bush is held in the
trees themselves. I have understood for a while that your soil is low in
nutrients given its age. It seems the trees store much of the nutrients
and
recycle it through the growing cycle as they shed leaves or die and decay.
Once the trees are gone so is much of the nutrient. The trees could
curvive
and grow as they existed in a closed cycle with the existing nutrients
recycled many many times. Once the nutrients were stripped away by
forestry
there was nowt left in the soil for regrowth. If true, a really
fascinating
example of closed cycles in nature and the way ignorant human activity can
destroy it.

The importation of exportation of ANY products on or off the land on which
it is raised or grown is mining. If you eat meat or vegetables that are not
grown on your own land, or wear clothes that are not produced from your own
land, you are involved in mining the fertility belonging to someone else.
We all do it and have done since time immemorial. I don't know anyone who
can only survive on the products of their own land or return all their
wastes to their own land.

If you have been reading this ng for some time, you may recall that at one
stage Otterbot made the comment that there is no such thing as unproductive
land. She was (generally) right because any land can be made productive but
it at the cost or mining somewhere else for nutrients. Tree cropping is
perhaps the most "sustainable" form of cropping but it is dependant upon the
soil and I have no doubt that there are some areas of Oz that could be very
much depleted after a single tree harvest. I can't think of any area off
the top of my head but I don't know about all our timber growing areas.

He also described in some length the salinisation of your soils. I knew
about it however the author described in length how the salt pans came to
exist, how irrigation can cause the salt level to rise and dryland
salinisation results from leaving productive land bare for much of the
year
allowing rain to wash salts through waterways or raise it to the surface.
The soluable salts then infest waterways.

If he wrote that about dryland salinity, then he doesn't know what he's on
about. Dryland salinity and salinity on irrigated land have differing
causes, as is perhaps the salinity of WA (which I have read has largely been
caused by millenia of onshore winds bringing in ocean salt which has then
settled on the land). That latter explanation could be pure crud, but I've
certainly read of that being an explanation for WA.

But having said that, European farming techniques did not suit most of this
country (and certainly not the dry interior) and it has taken till recent
decades for that fact to become evident. Dryland salinity is being
combatted effectively but slowly and it will be an ongoing battle for
decades. I know very little about salinity on irrigated land.