Date post: | 02-Jul-2015 |
Category: |
Technology |
Upload: | siani |
View: | 198 times |
Download: | 4 times |
Triple Green–Finding ways to meet the dual challenge of enhancing food production and meeting new sustainability criteria
Louise Karlberg, SEIABSTRACT: Sub-Saharan Africa (SSA) has been identified as a future hotspot for food shortage due to current low agricultural yields andhigh population growth. Two important ways to improve yields are: A) Bridging dry-spells by implementing water harvesting forsupplemental 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 increasedfood production. In SSA the total amount of nutrients in excreta is roughly equivalent to the amount of nutrients applied as chemicalfertilizers today. Productive sanitation systems can contribute to increasing the carbon content of the soil through increased plantproductivity and thus increased input of leaf and root litter to the soil; it therefore represents a mitigation strategy for climate change. Waterharvesting 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 theuse of productive sanitation in combination with water harvesting: producing higher yields (green) by adopting productive sanitationsystems and supplemental irrigation, using green water more efficiently, in a sustainable (green) way. One of the key questions is thuswhether the effect of combining these two management interventions is additive, multiplicative or perhaps only determined by the mostlimiting factor (water or nutrients). In addition, the following questions will be addressed within the project: (i) whether the use of a waterharvesting approach is socially acceptable, (ii) whether the use of urine as a fertilizer may have potentially negative effects on salinity inthe 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 waterholding capacity and soil carbon storage. If the results from combining these management interventions indicate significant long-termbenefits in terms of yield, carbon sequestration and the ability to bridge dry-spells, the next step would be to repeat this set-up on thefarmers’ field.
Human growth20/80 dilemma
Ecosystems60 % loss dilemma
Climate550/450/350
dilemma
Surprise99/1 dilemma
TThe Quadruple Squeeze
Dual challenge – environment and development
• Meeting food requirements – MDG’s
• Reducing atmospheric CO2 levels to 350 ppm
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
Climate Change< 350 ppm CO2 < 1W m2
(350 – 500 ppm CO2 ; 1-1.5 W m2)
Ocean acidificationAragonite 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 CyclesLimit 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
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?
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)
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)
Key question:
Are the current agricultural techniques sufficient to meet this dual challenge?
The Triple Green project - NigerAgricultural 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 SubkeStockholm Environment Institute
ANDMoussa Baragé and Moustapha Adamou
Abdou Moumouni University, Niamey, Niger
Triple Green - Rationale
Small scale agriculture in SSA
• Low yields
• Erratic rainfall
• Nutrient deficiency
Possible to double or even triple yields
Triple Green - MethodsTwo 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?
Triple Green – nutrients + water
0
50
100
150
200
250
Crop
yie
ld im
prov
emen
ts (%
)
Non fertilised
Fertilised
CA WH WSD
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.
Randomised block-trial on supplementary irrigated, urine fertilised millet
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
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?