5.1 Phosphorus and food security

1
5.1 Phosphorus and food security

• Should we worry about P?
• Are there substitutes for plant nutrients ?

Learning objectives Phosphorus as a resource,
and its links to sanitation and to food security
2
Our Globe sets the scene
We are in an era of unprecedented global
environmental change
Jan-Olof Drangert, Linköping University, Sweden
3
Water and phosphorus for food security

• Water molecules can be made by using a lot of
  energy
• Water is renewable (sun-driven cycle)
• Water is available in soil and replenished
  annually by rain
• 70 of global water use is for crop production
• A balanced diet results in the loan of 1300 m3/yr
  to each person on the planet based on current
  practice. This is 70 times greater than the 50
  l/d per person for basic water needs.

• Phosphorus (P) cannot be manufactured or
  destroyed
• P is essentially immobile and is mined in only a
  few countries
• P is naturally available in soil and depleted by
  crops
• 90 of global P extraction is for crop production
• A balanced diet results in the depletion of 22.5
  kg/yr of phosphate rock (3.2 kg/yr of P) per
  person based on current practice. 0.5 kg of this
  reaches the average persons food.

Source Cordell, Drangert White (2009a)
Both are critical to food production, but need to
be managed differently
4
Historical sources of phosphorus (1800-2000)
Humanity became addicted to phosphate rock in the
20th century!
5
Phosphorus status in soils in Europe
Source Efma, 2000b
6
World phosphate rock reserve estimates (000
tonnes)
P scarcity is worse than oil scarcity because P
CANNOT be substituted for in food production. So,
Source USGS and ESRI
the linear flow makes countries dependent
economically and politically
7
Food security phosphate rock dependence?
Courtesy IFA. Phosphate rock loading in Morocco.
8
Access to phosphate markets
World Bank, 2009
Future fertilizer price spikes are also possible
9
Peak phosphorus
The peak P timeline is disputed, but all agree
the quality of reserves is decreasing and
production costs are increasing
10
Phosphorus through the global food system
Only 1/5 of the P in mined rock reaches the food
on our plates!
11
Securing a sustainable phosphorus future


Business as usual

The future is not all dark!
Source Cordell et al., 2009b
12
A waste management hierarchy for P recovery
The extended waste management hierarchy includes
both liquid and solid waste in urban sanitation
systems and agriculture

1. Reduce (a) waste generation, and (b)
   harmful contents in products

2. Reuse the waste more or less as it is
3. Recycle the waste as input to new products
(including biogas)
4. Incinerate to extract the energy content in
the remaining waste
5. Safely landfill residues from the previous
steps.
Jan-Olof Drangert, Linköping University, Sweden
13
Can we eat climate-smart and phosphorus-smart?

• Think twice when shopping
  Dont buy more food than
  you have time to eat
• Eat up the food you cook
  Serve reasonable portions and
  use the leftovers
• Use your senses
  Look, smell,
  taste and feel the food. Most foodstuffs last
  longer than their indicated use-by date if
  they are stored properly
• If you want to eat meat
  Choose local produce and
  try to eat fish, chicken and no beef
• Eat more vegetarian food
  Especially root crops and
  legumes
• Choose fruits and vegetables of the season
  Preferably local products

Source Swedens National Food Adminstration
Report 20089
14
Nutrients in human excreta
Amount of nutrients from an average Swede per year
 The Urine Equation  An adult eats 250 kg of
cereals per year, which has been grown on less
than 250 m2 and fertilized to more than fifty per
cent by the persons urine.
Jan-Olof Drangert, Linköping University, Sweden
15
Nutrient fertiliser values and CO2 emissions
Million SEK/yr
Economic value of NPKS in toilet water and
sludge, and reduced emissions of GHG compared to
use of chemical fertilisers


H. Jönsson et al., 2012
16
Nutrient flows originating from households

• Today

Compost 20 P, 20 N
HH
Jan-Olof Drangert, Vatema
17
Nutrient flows originating from households
Year2030
Compost 33 P, 22 N
HH
WWTP 20 P 5 N
Jan-Olof Drangert, Vatema
18
A pig and its potential impacts
Greenhouse gases (18)
Meat
Import
Cereals
Recycling to farmland
2.5 pigs/yr
3.5 m3 faeces
4/1.6/1 kg/yr
5 m3 urine
Can fertilise 1500 m2 and produce 800 kg of rice
5/0.4/3 kg/yr
Eutrophication and dead zones in seas
Jan-Olof Drangert, Linköping University, Sweden
19
Loss of food in each step of the food chain

Source FAO, 2011
20
Plant requirement and nutrient removal

Source Håkan Jönsson, SLU, Sweden
21
Why is it so difficult to apply P?
1000-2000 kg/ha.
10-100 kg/ha.
0.01-0.1 kg/ha.
Plants need 10-30 kg/ha, but 0.5 kg/ha/day
Fast (t,d,w) transport
Slow (m,y) transport
SourceStoumann Jensen, L. 2010
22
Exercise a closer look at phosphorus flows
Start from the end!
Step 1
Step 2
Step 3
Step 4
Source Cordell, Drangert White (2009a)
Stay vegetable-based, and return farm waste, your
excreta, household and city organic waste to soil
!!!
23
Was the strong link between the water and
sanitation sectors in the 20th century a brief
detour in human history?
What will come next ?
Most common
Parenthesis?
agriculture sanitation
water sanitation
agriculture sanitation
All rural
Essentially urban
Jan-Olof Drangert, Linköping University, Sweden
24
Epilogue
The green revolution in the 1950s saved the world
from hunger - by using irrigation water, new crop
varieties and chemical fertilisers
Next revolution must be to recycle the nutrients
used in food production !
Two major opportunities for increasing the life
of expectancy of the worlds phosphorus resources
lie in recycling by recovery from municipal and
other waste products and in the efficient use in
agriculture of both phosphatic mineral fertilizer
and animal manure European Fertilizer
Manufacturers Association (2006)
Jan-Olof Drangert, Linköping University, Sweden