Presentation from the WCCA 2011 conference in Brisbane, Australia.

1. Trade-offs for
biomass uses at
farm level -
Livestock vs soil
cover
Naudin K, Bruelle
G, Salgado P, Penot
E, Scopel E, Lubbers M,
de Ridder N, Giller K E

2. The issue
To much biomass Not enough biomass
for cattle
Feed the cows
or feed the soil ?
Not enough biomass
to cover the soil

3. CONSERVATION
AGRICULTURE
IN THE LAC
ALAOTRA
REGION OF
MADAGASCAR

4. Alaotra Region
102 000 ha of paddy
Fields
7 hours from
Antananarivo by car
750 m et 1 100 m ASL
Annual rainfall : 850
mm, lot of variations, 7
to 10 months whithout
rain

5. Alaotra Region-Landscape
Poor water
control paddy
fields
Irrigated
paddy
fields
Hills Alluvials
soils

6. CA in the Alaotra region
2500
First experimentation in 1998 2000
Surface Number of adopting
2010-2011 : 1500
• 2000 farmers 1000
• 1200 ha 500
Strong support from 0
2003-04 2004-05 2005-06 2006-07 2007-08 2008-09 2009-10
developpement project, Source: Penot et al, this congress
public funds, NGO
EXAMPLE OF
PICTURE
Annual rotation: rice/Vicia villosa Bi-annual rotation: maize+dolichos//rice
Source : Séguy et al

7. METHODS

8. Optimization throught Linear
programming - Theory
Goal : maximize x1+x2
With following constraints
• x1≥0
• x2 ≥0
• x2-x1≤1
• x1+6x2 ≤15
• 4x1-x2 ≤10
X1+x2=5
X1+x2=4
X1+x2=2
Matousek & Gartner, 2007

9. GANESH Goals oriented Approach to use No till
for a better Economic and environmental sustainability for Smallholders
GANESH:
• 21 variables
• 32 equations

10. GANESH - Crops
4 kinds of
fields
1. Poor water
control paddy
fields
2. Hillsides
3. Alluvial soils
4. Irrigated
paddy fields
Each crop is
characterized
by its needs
and outputs

11. GANESH- Livestock
LIVESTOCK
• 4 kinds of
animals
1. Zebu male
2. Zebu female
3. Dairy cows
improved
breed
4. Dairy cows
local breeds
• Each animal is
characterized by
its needs and
outputs

12. GANESH- Farm
Farm structure
• Work force
• Self
consumption
needs
External factors
• Milk market

13. GANESH- Optimisation
Total farm
income
Constraints :
• Work
availability
• Fields
• Forage
needs
• Soil cover %

14. GANESH- Biomass export and
soil cover
Adapted from: Naudin et
al. Trade-offs between
biomass use and soil
cover. The case of rice-
based cropping systems in
the Lake Alaotra region of
Madagascar., Exp.Agric. In
press
Why soil cover ?
• Has impact on: weeds pressure, erosion control, water
balance.
• Not yet possible to link % of soil cover and crop yield impact

15. RESULTS
DISCUSSION

16. Simulation
Alluvial Soil Poor water
1 000 m2 Irrigated control
Alluvial Soil Paddy field paddy field
1 000 m2 4 000 m2 2 000 m2
Poor water
+ 3 children control
Hill 1 000 m2
paddy field
Hill 1 000 m2 2 000 m2
Hill 1 000 m2
Hill 1 000 m2
EXEMPLE
D’IMAGE
0
12

17. Simulation
What is the impact of an increase in the herd size
• in term of % of the area cultivated in CA
• in term of economic balance of livestok activities

18. Area with CA, alluvial soils
Year 2

19. Liverstock economic balance
Year 2

20. With a limiting milk market
12,000
10,000
Milk -forage bought (kAr)
8,000 12
10 Nb of cows
6,000 8
6
4,000
4
2,000
2
0
0
-2,000 No 32
limit 16 Milk marketable l/ day
-4,000
Constraint: soil cover > 90%

21. Conclusion
Linear programming can be a useful tool to take
into account both negative and positive interactions
between CA and husbandry at farm level
What are the limits in terms of complementarily, or
competition for:
• Biomass that can be removed from field
• Size of the herd
• Cropping systems performances (biomass and grain
production)
• Market demand for animal products
To go further: need of more data about relation
between soil cover and crop yields
• Short term impact of soil cover on: weeds, water balance
• Mid term impact of soil cover on : nutrient cycling, soil
organic matter

22. Thank you for your attention
Merci de votre attention !