The Chemistry of Farming - Book Review

["Paddy Apling" <e.c.apling@xxxxxxxxxxxxxxxxxx>]

Those who believe that "organic farming" is the future should read this:

Going one better than nature?

JOHN EMSLEY; Dept of Chemistry, University of Cambridge, UK. Nature 410,
633 - 634 © Macmillan

Book Review: Enriching the Earth: Fritz Haber, Carl Bosch, and the
Transformation of World Food by Vaclav Smil ; MIT Press: 2001. 339 pp.
$34.95, £23.95

The greatest catastrophe that the human race could face this century is
not global warming but a global conversion to 'organic' farming ? an
estimated 2 billion people would perish. That is the underlying message of
this remarkable book, which charts the discovery of nitrogen fixation ?
the conversion of unusable atmospheric nitrogen to useful ammonia ? and
its impact on the world's food supply.

If crops are rotated and the soil is fertilized with compost, animal
manure and sewage, thereby returning as much fixed nitrogen as possible to
the soil, it is just possible for a hectare of land to feed 10 people ?
provided they accept a mainly vegetarian diet. Although such farming is
almost sustainable, it falls far short of the productivity of land that is
fertilized with 'artificial' nitrogen; this can easily support 40 people,
and on a varied diet. Of course, 'organic' farming should be encouraged in
order to recycle compost and dung. But it can never compete with the
bountiful supply of agrochemical nitrogen, which now meets about 40% of
the world's dietary needs.

Nitrogen is abundant in the atmosphere, but in a form that is difficult to
extract; only a few microbes and plants have the capacity to do this. Yet,
thanks to their efforts over aeons of time, a whole planetary ecology can
now be sustained. This organic nitrogen will even support continued
agriculture if properly managed, but it imposes a maximum on the density
of the human population.

All this changed on 3 July 1909, when two German chemists, Fritz Haber and
Carl Bosch, proved that it was possible to convert atmospheric nitrogen
into ammonia on an industrial scale. Today there are Haber?Bosch chemical
plants around the world, producing 150 million tonnes of ammonia a year,
most of which goes into making fertilizer. The nitrogen input into farmed
land from these fertilizers now exceeds the natural input. Even low-income
countries can afford Haber?Bosch factories, and these should begin to turn
around food production there, just as they did in high-income economies.

In the final chapter of Enriching the Earth, Vaclav Smil of the University
of Manitoba admits that he originally intended to write a biography of
Haber and Bosch, but he quickly realized that an account of the effects of
their research would be far more interesting, and concentrated on this. He
was right to do so.

Smil begins by looking at the fact that all living things need nitrogen in
order to make amino acids, the building-blocks for the proteins on which
life depends. He explains how nitrogen is fixed naturally, and how
traditional farming takes this from the soil, but with only partial
success at returning waste material to fertilize future crops. The first
successful nitrogen fertilizers came from the Chilean guano deposits in
the nineteenth century, a clearly limited supply.

The central theme of Enriching the Earth tells of Haber's struggle to make
hydrogen gas (H2) react directly with nitrogen gas (N2) to form ammonia
(NH3), and of Bosch's faith that the process could be made to work
commercially. Bosch then convinced the German chemical company BASF to
invest in it. Thus was an industry born. But it was not immediately seen
as the answer to the world's food supply; instead, it fed into Germany's
need for ammunition to fight two world wars. Ammonia from the Haber?Bosch
factories was converted to nitric acid and thence to explosives. After
1945, however, the overwhelming use of such factories was to fix nitrogen
for fertilizers.

Smil recounts how the industry developed, and how much of the world's
population is now supported by it. He discusses how this chemical bounty
is disbursed. Relatively little is used by US agriculture, but a great
deal by Chinese farmers. Smil considers what will happen when developing
economies also want their protein to be in the easily digested and tasty
kind that comes from meat, even though this is the least efficient way of
producing food. But can our planet support another 5 billion people on a
Western diet, and won't more food simply encourage more humans to have yet
more children? Smil's answer is found in his chapter "Nitrogen and
civilization". The future looks surprisingly reassuring. The annual
increase in global population will continue to decline even though food
production is rising, and the total might well peak at less than 9 billion
by the year 2050, declining thereafter.

This is a wonderful book, highly readable and replete with referenced
data. It is soundly based on the chemistry that underpins our food supply,
or at least the protein part of it, and is an ideal corrective to the
misleading ideas we are constantly being fed by the organic food movement.
Humans have a stark choice to make: do we farm four hectares of land
'organically' to feed 40 souls, or do we farm one hectare 'artificially',
thereby leaving the other three to natural woodland and wildlife? There is
a place for 'organic' farming, but only insofar as it permits us to
recycle nitrogen that would otherwise go to waste.

Forwarded by
Paddy
NFHS Member #5594
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