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synthesis from the nitrogen contained in air, phosphate rock on the other hand is
scarce (82% of the phosphorus is used as fertiliser of which only one-fifth is taken up
by crops). According to Wellmer (2008) at the current rate of consumption based
on proven reserves, the peak production of phosphate rock is expected at some point
between 2030 and 2040. To that effect, Cordell et al. (2009) presented a sustainable
scenario for long-term phosphorus supply and demand as shown in Fig. 1.3. It in-
dicates that the global supply of phosphates will not meet future demand without
drastic changes within the recycling sector, in the application of fertiliser, improve-
ments in food chain production and alterations to the Western diet. This places
phosphate rock as one of the most critical elements for development, either as a
bioenergy or as an essential element in the food chain 13 . No doubt future gen-
erations will pay the highest price because whereas substitutes for depleted fossil
fuels exist, plants and other biota require phosphorus to live with no possibility of
replacing it with an alternative. In other words, the amount of biomass that can
be produced is absolutely limited by the phosphorous resources of the planet and
mankind's capacity to recycle it 14 . Any solution will almost certainly sharply raise
future food prices and bioenergy costs.
90
80
Business-as-usual
HISTORICAL FUTURE
70
Changing diets
60
~2/3
INCREASED
P USE
EFFICIENCY
Food chain efficiency
50
40
Agricultural efficiency
30
Other
Food waste
20
Crop residues
~1/3
P RECOVERY
& REUSE
Manure
10
Phosphate
rock
Human excreta
0
1950
1975
2000
2025
2050
2100
2075
Year
Fig. 1.3 A sustainable scenario for the long-term phosphorus supply and demand. Redrawn from
Cordell et al. (2009) with permission from IWA Publishing
13 In the sense that phosphorous forms the bone structures composed of carbonated hydroxyapatite
(Ca 10 (PO 4 ) 6 (OH) 2 ).
14 For more information, see also http://www.phosphorusfutures.net.
 
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