Plant propagation: Sexual and Asexual propapagation.pptx
Status and challenges of soil management in Africa - Bernard Vanlauwe
1. Status and challenges of soil
management in Africa
Bernard Vanlauwe
International Institute of Tropical Agriculture
Nairobi, Kenya
b.vanlauwe@cgiar.org
2. Food security for 9 billion people?
Closing the yield gap
Increasing production ceilings
Expanding aquaculture
Reducing waste (…30-40% of the produce)
Changing diets
Demography
The challenge…
3.
4. The yield gap…
FAO and IFDC, 2002
J. Koo, 2010
Maize yield reduction (% of potential)
5. $ 200-500 /tonne urea world market 2010-2011
$ 900-1.400 /tonne urea in Bukavu (DRC)
The ‘Coca-cola’ paradox
11. Importance of policy and good governance
In Africa, there are good recent examples of where policy is
making a difference in farmer livelihoods (e.g., Malawi,
Rwanda, Kenya)
12.
13. 70’s: First paradigm:
‘Overcome soil constraints to fit plant requirements
through purchased inputs’
‘When mechanization is feasible and
fertilizers are available at reasonable
cost, there is no reason to consider
the maintenance of SOM as a major
management goal’
Sanchez, 1976
16. 90’s: 2nd Paradigm (Sanchez, 1994):
‘Overcome soil constraints by relying on biological
processes by adapting germplasm to adverse soil
conditions, enhancing soil biological activity, and
optimizing nutrient cycling to
minimize external inputs and
maximize their use efficiency’
The revival of green manures in East
Africa (e.g., Tithonia diversifolia;
Crotalaria sp)
20. Fertilizer works (and interacts with improved
varieties)…
FAO fertilizer
program
(FAO, 1989) :
Average response
of 750 kg grain/ha to
medium NPK rates
Value–to–Cost
ratios between 1.1
and 8.9, usually
above the required
ratio of 2
Maize yield in
East DR Congo
23. Time, years
0 20 40 60 80 100
TotalC(tha-1
)
10
20
30
40
50
60
Commercial
Communal
Zingore, Manyame, Nyamugafata
and Giller (2002)
Impact of fertilizer x variety on soil C
24. Now: Integrated Soil Fertility Management
‘The application of soil fertility management
practices, and the knowledge to adapt these to
local conditions, which maximize fertilizer and
organic resource use efficiency and crop
productivity. These practices necessarily include
fertilizer and organic input management in
combination with improved germplasm’
26. Principles of Conservation Agriculture
1. Minimize soil disturbance by reduced or zero-tillage
2. Keep the soil covered with organic materials (crop harvest
residues or cover crops)– at least 30% soil cover
3. Use crop rotations/associations
Important additional rule: No minimal tillage without mulch
retention!
4. Use fertilizer [additional principle for Africa]
28. 0
20
40
60
80
100
0 5 10 15 20
Time (weeks)
Residuecover(%)
Good - with tillage Good - without tillage
Medium - with tillage Medium - without tillage
Poor - with tillage Poor - without tillage
SED
Guto et al. (2011), Agron. J. Guto et al. (2011), Agron. J.
Good
Medium
Poor
Tillage x residue management in
Central Kenya
Niches for CA
30%
29. ProductivityThe destination is clear, less so the road to follow
Natural resource status
Agronomicefficiency
Current
practice
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
Germplasm
& fertilizer’
+ Organic
resource mgt
Germplasm
& fertilizer
‘Full ISFM’
Move towards ISFM
Increase in knowledge
Responsive soils
Poor, less-responsive soils
A
B
C
X
30.
31. Importance of enabling conditions
Role of input and output markets: ISFM requires
investments in production factors; income is a requirement
to move towards full ISFM.
Models: Many interesting models to link smallholders to
input supply chains and profitable markets are being
piloted/implemented at scale.
32. Organic agriculture is constrained by
organic inputs; OK for niche markets
N: Some BNF Low use efficiency!
P: Rock phosphates Availability?
K: K salts; roots and tubers Availability?
Other (micro)nutrients: S, Zn, Mg, etc ??
34. Farmer first!
Interview Prem Warrior, BMGF, 17 Oct 2012
Question:
‘What’s the right thing to do
for smallholders in Africa?’
Response:
‘It’s for her to decide!’
Thank you!
Merci beaucoup!
Asante sana!