Skip to Content.
Sympa Menu

livingontheland - [Livingontheland] Running dry

livingontheland@lists.ibiblio.org

Subject: Healthy soil and sustainable growing

List archive

Chronological Thread  
  • From: "Tradingpost" <tradingpost@lobo.net>
  • To: livingontheland@lists.ibiblio.org
  • Subject: [Livingontheland] Running dry
  • Date: Thu, 18 Sep 2008 12:38:45 -0600



Running dry
http://www.economist.com/world/international/displaystory.cfm?story_id=12260907
Sep 18th 2008
>From The Economist print edition
The world has a water shortage, not a food shortage

MOST people may drink only two litres of water a day, but they consume about
3,000 if the water that goes into their food is taken into account. The rich
gulp down far more, since they tend to eat more meat, which takes far more
water to produce than grains. So as the world’s population grows and incomes
rise, farmers will—if they use today’s methods—need a great deal more water
to keep everyone fed: 2,000 more cubic kilometres a year by 2030, according
to the International Water Management Institute (IWMI), a research centre, or
over a quarter more than they use today. Yet in many farming regions, water
is scarce and likely to get scarcer as global warming worsens. The world is
facing not so much a food crisis as a water crisis, argues Colin Chartres,
IWMI’s director-general.

The solution, Mr Chartres and others contend, is more efficient use of water
or, as the sloganeers put it, “more crop per drop”. Some 1.2 billion people,
about a fifth of the world’s population, live in places that are short of
water (see map). Farming accounts for roughly 70% of human water consumption.
So when water starts to run out, as is happening in northern China, southern
Spain and the western United States, among other places, farming tends to
offer the best potential for thrift. But governments, whether to win votes or
to protect the poor, rarely charge farmers a market price for water. So they
are usually more wasteful than other consumers—even though the value they
create from the water is often less than households or industry would be
willing to pay for it.

The pressing need is to make water go further. Antoine Frérot, the head of
the water division of Veolia Environnement, a French firm, promotes
recycling, whereby city wastewater is treated until it can be used in
industry or agriculture. This costs about a third less than desalination, and
cuts pollution. He expects his recycling business to quadruple in the next
decade.

Yet as Mr Frérot himself concedes, there are many even cheaper ways to save
water. As much as 70% of water used by farmers never gets to crops, perhaps
lost through leaky irrigation channels or by draining into rivers or
groundwater. Investment in drip irrigation, or simply repairing the worst
leaks, could bring huge savings.

Farmers in poor countries can usually afford such things only if they are
growing cash crops, says David Molden of IWMI. Even basic kit such as small
rainwater tanks can be lacking. Ethiopia, for example, has only 38 cubic
metres of storage capacity per inhabitant, compared to almost 5,000 in
Australia. Yet modest water storage can hugely improve yields in rain-fed
agriculture, by smoothing over short dry spells. Likewise, pumping water into
natural aquifers for seasonal storage tends to be much cheaper than building
a big dam, and prevents the great waste of water through evaporation.

Even when water is scarce, it is often squandered. Mr Molden cites the
example of cotton-farmers in Uzbekistan, who used to receive a fixed
allocation of water for irrigation whether they needed it or not, in a
holdover from the days of Soviet central planning. Simply putting farmers in
control of the irrigation network, and allowing them to decide how much water
they needed, cut consumption by 30%.
Science Photo Library Cotton paying a high price for water

Similarly, rice farmers can sharply cut water consumption by flooding paddy
fields only some of the time. Wheat growers in hot places such as India and
Australia can conserve water by minimising tilling, leaving a layer of mulch
on the fields’ surface to absorb rainwater and limit evaporation. In arid
regions like the Middle East, Mark Zeitoun of the London School of Economics
suggests substituting thirsty crops such as oranges with more abstemious
olives and dates. Ideally, countries that are short of water would
concentrate on growing the most valuable cash crops, and use the proceeds to
import staples.

Agronomists are beginning to devise tools to help monitor the efficiency of
water use. Some have designed algorithms that use satellite data on surface
temperatures to calculate the rate at which plants are absorbing and
transpiring water. That allows governments and development agencies to
concentrate their efforts on the most prodigal areas.

But efficient use of water, cautions Pasquale Steduto of the United Nations’
Food and Agriculture Organisation, is just one step to better agricultural
yields. Even if farmers use the right amount of water they also need decent
seeds and enough fertiliser. In Africa in particular, these and other factors
such as pest control, storage and distribution are a bigger drag on yields
than a shortage of water.

Raising yields does not always involve greater water consumption, especially
when farms are inefficient. It would take little extra water to double cereal
output in many parts of Africa, Mr Molden argues. IWMI reckons that some
three-quarters of the extra food the world needs could be provided simply by
bringing yields in poor countries closer to those of rich ones. That is more
palatable than the puritanical alternative: giving up meat and other thirsty
products altogether.






Archive powered by MHonArc 2.6.24.

Top of Page