VickyN wrote:
The cost in buying fertiliser and applying it is not always
justified by

even the short-term returns, that is it is applied in excess of the
optimum
in some cases for reasons other than being demonstrated to be cost
effective. OTOH I know of no analysis that shows we could feed the
world's
population by organic methods. There may be some focus on this issue
over
the next few decades as sources of mineral phosphorus compound become
exhausted and the cost of nitrogen fixing rises with energy costs.

I'm not sure what exactly you're getting at here. How is the cost of
buying fertiliser not justified by the short term returns? I also
don't understand your take on phosphorus as there is plenty sitting
in soils all over the world already.


Decisions about applying fertiliser are not always made considering
cost-benefit analysis but on other considerations such as the fertiliser
salesman told me so, or Grandpa always did it, or I want to get a better
yield than my neighbour. Fertilisers have been subsidised in the past
corrupting the market.

Soils having such high levels of soil phosphorus no longer need to be
fertilised with more than the amount of phosphorus removed in
harvest. In fact, many agricultural soils in industrialised
countries with long histories of phosphorus build-up from manure or
fertilizer application have accumu*lated so much available
phosphorus that little if any additional phosphorus is needed until
phosphorus is drawn down to more moderate levels over a period of
years.


Millions of tons of superphosphate has been applied to the soils of
Australia but still they apply more.

Professor Stefano Grego

Surely we can either harvest it, or implement solubilising bacteria to
help break down the unavailable forms of P. How can there be a P
shortage, even in a few decades, when there is so much in the land
already?


The fertiliser companies will tell you it ain't so. Add more, and more.
Quick!


Land always needs rotation, especially so if you grow a monoculture.
This
is not limited to where chemical fertilisers have been applied.

Land still needs to be rotated because of high application of
fertilisers building to toxic levels... particulalry P (locks out
iron). Ah, maybe rotated is the wrong word, easy to confuse with
ordinary crop rotation I suppose. So let's just say land is left
unusable for certain periods of time.


Dare you explain the connection between the state of soil bacteria
and humans poisoning themselves by employing poor food handling
practices?

Bacteria is a very basic form of life, capable of genetic shifts that
will change it from one thing into another. we eat e.coli all the
time. our stomach acids kill it usually... but something is causing
to e.coli to become virulent, and it is becoming virulent with
greater frequency. There are some that suggest this is down to
artificial fertilisation by man. The reasoning being, I believe, that
the fertilisation is killing off the friendly bacteria and fungi, the
beneficials... it is killing them off because they haven't anything
to do. This shift is having a knock on effect with the bad microbes
which is why we're seeing more cases of virulent e.coli.
I'm not sure i agree with this, but it does make some logical sense
so I cannot discount it easily.


An open question then.



Please provide some evidence for that claim. What are the costs of
that

method compared to others? How do you feed cattle or sheep
hydroponically?
Would that be cost effective?

David

I meant only in regards to crop farming. Leaving the land alone for a
while would leave plenty to feed cattle or sheep. we could also still
crop farm, only doing it organically, at least more intelligently.
cash crops could be left to sterile hydroponic growing. Hydroponic
systems may be expensive to set up but are not very expensive to
maintain. If built in the right way you can have hydroponic systems
that run with minimal power. All it takes to keep enough o2 in the
water is the continual motion of that water.

Why is hydroponics only done now for high value cash crops if it is so
cheap? Will the nutrient fluids remain cheap? Where will the cheap energy
come from to make your N components? Where will the P components come from
if all the cheap phosphate rock is exhausted?

D