This study was presented during the conference “Production and Carbon Dynamics in Sustainable Agricultural and Forest Systems in Africa” held in September, 2010.

1. Triple Green–Finding ways to meet the dual challenge of enhancing
food production and meeting new sustainability criteria
Louise Karlberg, SEI
ABSTRACT: Sub-Saharan Africa (SSA) has been identified as a future hotspot for food shortage due to current low agricultural yields and
high population growth. Two important ways to improve yields are: A) Bridging dry-spells by implementing water harvesting for
supplemental irrigation which results in more efficient use of the available green water and augmentation of the green water resource. B)
Implementing productive sanitation systems, i.e. the collection of and safe reuse of human urine and faeces as a fertiliser for increased
food production. In SSA the total amount of nutrients in excreta is roughly equivalent to the amount of nutrients applied as chemical
fertilizers today. Productive sanitation systems can contribute to increasing the carbon content of the soil through increased plant
productivity and thus increased input of leaf and root litter to the soil; it therefore represents a mitigation strategy for climate change. Water
harvesting is a climate change adaptation strategy, since dry-spells are expected to become increasingly common under a future climate.
Within the triple green project, we investigate the opportunities and challenges to increased crop productivity and food security through the
use of productive sanitation in combination with water harvesting: producing higher yields (green) by adopting productive sanitation
systems and supplemental irrigation, using green water more efficiently, in a sustainable (green) way. One of the key questions is thus
whether the effect of combining these two management interventions is additive, multiplicative or perhaps only determined by the most
limiting factor (water or nutrients). In addition, the following questions will be addressed within the project: (i) whether the use of a water
harvesting approach is socially acceptable, (ii) whether the use of urine as a fertilizer may have potentially negative effects on salinity in
the soil in arid climates, (iii) to what degree carbon sequestration takes place.
In the second phase of the project the intention is to also include conservation agriculture, as an additional way of improving soil water
holding capacity and soil carbon storage. If the results from combining these management interventions indicate significant long-term
benefits in terms of yield, carbon sequestration and the ability to bridge dry-spells, the next step would be to repeat this set-up on the
farmers’ field.

2. Human growth
20/80 dilemma
Ecosystems
60 % loss dilemma
Climate
550/450/350
dilemma
Surprise
99/1 dilemma
TThe
Quadruple
Squeeze

3. Dual challenge – environment
and development
• Meeting food requirements – MDG’s
• Reducing atmospheric CO2 levels to 350 ppm

4. Climate
Change
Ocean
acidification
Ozone
depletion
Global
Freshwater
Use
Rate of
Biodiversity
Loss
Biogeochemical
loading: Global
N & P Cycles
Atmospheric
Aerosol
Loading
Land
System
Change
Chemical
Pollution
Planetary
Boundaries

5. Climate Change
< 350 ppm CO2 < 1W m2
(350 – 500 ppm CO2 ;
1-1.5 W m2)
Ocean acidification
Aragonite saturation
ratio > 80 % above pre-
industrial levels
(> 80% - > 70 %)
Ozone depletion
< 5 % of Pre-Industrial 290 DU
(5 - 10%)
Global Freshwater Use
<4000 km3/yr
(4000 – 6000 km3/yr)
Rate of
Biodiversity Loss
< 10 E/MSY
(< 10 - < 1000
E/MSY)
Biogeochemical
loading: Global
N & P Cycles
Limit industrial
fixation of N2 to 35
Tg N yr-1(25 % of
natural fixation)
(25%-35%)
P < 10× natural
weathering inflow to
Oceans
(10× – 100×)
Atmospheric
Aerosol Loading
To be determined
Land System
Change
≤15 % of land
under crops
(15-20%)
Chemical Pollution
Plastics, Endocrine Desruptors,
Nuclear Waste Emitted globally
To be determined
Planetary
Boundaries

6. Example - carbon sequestration in
terrestrial ecosystems
• Carbon sequestration by
reforrestation
• Carbon sequestration in agricultural
soils
• Improved water productivity by C-
fertilisation
What is the impact on water and food production?

7. Reforrestation
An annual C seq rate of 1.6 GtC/yr by 2050 (Hansen
et al) results in:
• 1300 km3/yr increased consumptive water use by
2050 – reductions in runoff (trade-off)
• If reforrestarion on current agricultural land:
competition with food production (trade-off)

8. C seq on agricultural lands –
Preliminary estimates
An annual C seq rate of 0.4-1.2 GtC/yr by 2050 (Lal
et al) results in:
• 4000 – 10000 km3/yr increased consumptive water
use by 2050 – reductions in runoff (trade-off)
• NOT realistic – assumes same water productivity
• Results in concurrent yield improvements
(synergies)

9. Key question:
Are the current agricultural
techniques sufficient to meet this
dual challenge?

10. The Triple Green project - Niger
Agricultural management interventions for a new
green revolution, in a green (sustainable) way
based on green water, in the tropics
Louise Karlberg, Linus Dagerskog, Elisabeth
Kvarnström and Jens-Arne Subke
Stockholm Environment Institute
AND
Moussa Baragé and Moustapha Adamou
Abdou Moumouni University, Niamey, Niger

11. Triple Green - Rationale
Small scale agriculture in SSA
• Low yields
• Erratic rainfall
• Nutrient deficiency
Possible to double or even
triple yields

12. Triple Green - Methods
Two important ways to improve yields are:
A)Bridging dry-spells by implementing water harvesting
for supplemental irrigation
B)Implementing productive sanitation systems, i.e. the
collection of and safe reuse of human urine and
faeces as a fertiliser for increased food production.
What are the added benefits of combining the two?

13. Triple Green – nutrients + water
0
50
100
150
200
250
Cropyieldimprovements(%)
Non fertilised
Fertilised
CA WH WSD

14. Triple Green – climate change
Mitigation: Productive sanitation + water harvesting
systems can contribute to increasing the carbon
content of the soil through increased plant
productivity and thus increased input of leaf and root
litter to the soil
Adaptation: Water harvesting can help bridging dry-
spells, which are expected to become increasingly
common under a future climate.

15. Randomised block-trial on supplementary
irrigated, urine fertilised millet

16. Expected results
Field data will be combined with a physically based
ecosystems model to study:
• Carbon sequestration, water flows, yields and salt
accumulation over time under different management
regimes.
Moreover, the model will be used to study the impact of a
changed climate on these variables

17. Scaling out
To answer this questions, we need:
• Assessments across scales
• Integrated assesments focussing on several sustainability
criteria (e.g. nutrients, land-use, carbon and water)
• A multi-sectoral approach (e.g. food, feed, fuel, fibre)
• Assessments of ecosystem services, livelihoods, resilience,
policies and institutions, etc.
If implemented on a larger scale – would we produce
enough food and still remain sustainable?