integrated soil fertility management (isfm) in sub-saharan africa
TRANSCRIPT
Integrated Soil Fertility Management
(ISFM) in Sub-Saharan Africa:
Concepts and practice
Bernard Vanlauwe
International Institute of Tropical Agriculture (IITA)
Nairobi, Kenya
This is not about ‘rocket science’…
… or dogma’s
… but about applying good soil management
principles derived
through the
application of the
standard rules of
scientific discovery!
Old and degraded soils…
Poor infrastructure…
… expensive inputs!
Many factors affect crop yield…
Small farms…
… poor people!
Harris et al, 2012
USD/ha
Current Improved
400
200
Small farms…
… eternally poor people? Land (hectare) required to produce 1 USD/day as a function of net returns
from crop production
Net returns from crop production, $/ha
Lan
d r
equ
ired
to
pro
du
ce
$1/p
erso
n/d
ay,
ha
Good soil
Poor soil
Variability in soil fertility… Same farm…
Same variety…
Same inputs…
Same management…
Same weather…
Variation in farmer’s resources, ambitions
and risk-taking abilities
Titonnell et al, 2011
Densely populated areas: Intensification
Forested areas: Intensification or expansion?
It is possible!
Maize in Kenya
Millet in Niger
No fertilizer, no intensification…
IFA, 2001
0
1000
2000
3000
low medium high
manage me nt
ma
ize
yie
ld [
kg
ha-1]
control (no fertilizer applied)
fertilizer applied
Mai
ze g
rain
yie
ld (
kg/h
a)
Management
intensity (planting date,
crop density,
time of P
application);
Tinfouga, Mali
Bationo et al.,
1997
Universal principles of nutrient management
Improved germplasm: matching better
nutrient supply with better demand
3.15.6
3.3
3.2
0
2000
4000
6000
Kasaï Kuleni BH140 BH540
Gra
in y
ield
(kg
ha-1
)
without fertilizer with fertilizer
SED* (variety effect)
SED** (fertilizer)
3.15.6
3.3
3.2
0
2000
4000
6000
Kasaï Kuleni BH140 BH540
Gra
in y
ield
(kg
ha-1
)
without fertilizer with fertilizer
SED* (variety effect)
SED** (fertilizer)
Maize yield in
East DR Congo
Total millet dry matter yield as affected by long-termapplication of crop residues and fertilizer, Sadore, Niger
0
1000
2000
3000
4000
5000
6000
7000
8000
9000
1982 1984 1986 1988 1990 1992 1994 1996
Year
To
tal
mil
let
dry
matt
er
(kg
ha-1
)
Control
Crop residues
Fertilizer
Crop residues + fertilizer
0
20
40
60
80
100
120
without
crop
residues
with crop
residuesD
ry m
att
er
/ N
ap
pli
ed
(k
g k
g-1)
Co-application of fertilizer and organic inputs
But fertilizer is often
not enough…
N+P Fertilizer
Manure
+ N
Variability in response to fertilizer…
Non-responsive soils
‘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 appropriate fertilizer
and organic input management in combination with
the utilization of improved germplasm’
Integrated Soil Fertility Management
Integrated Soil Fertility Management
Ag
ron
om
ic e
ffic
ien
cy
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
ISFM works for maize-based systems!
0
5
10
15
20
25
30
Local Improved - OPV Improved -
Hybrid
N-A
E (
kg
gra
in k
g-1
N)
Average
SED
Vanlauwe et al, PLSO, 2011
ISFM works for maize-based systems!
Vanlauwe et al, PLSO, 2011
0
500
1000
1500
2000
2500
3000
3500
4000
4500
5000
5500
1986 1987 1988 1989 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006
Ma
ize
gra
in y
ield
(k
g h
a-1
)
control - fertilizer control + fertilizer
Leucaena - fertilizer Leucaean + fertilizer
Senna - fertilizer Senna + fertilizer
Long term trials as essential components of
an intensification strategy Is fertilizer used in the context of ISFM a valid entry point
towards sustainable system intensification?
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!
1. 2. 3.
http://www.fao.org/ag/ca/5.html
‘Time to’ CA
Potential benefits of CA
Coordinated Research Project on CA,
facilitated by IAEA (2005 – 2010) [Various countries and
continents, systems,
climates, etc]
Overall conclusions:
1. CA does not
necessarily improve crop yields in the short term
2. CA does not necessarily increase soil C stocks
3. CA systems appear to have more stable yields under
varying rainfall conditions [ climate change adaptation]
Niches for CA
X
?
0
20
40
60
80
100
0 5 10 15 20
Time (weeks)
Resid
ue c
over (
%)
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%
ISFM and Conservation Agriculture
The common quest for biomass…
Ag
ron
om
ic e
ffic
ien
cy
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
This talk…
1. Smallholder farming in SSA is complex – attempts to
intensify need to work within that complexity
2. Literature and field evidence shows that ISFM addresses
such complexity and provides immediate benefits to farmers
(beware of non-responsive soils)
3. Long term ISFM trials are required to assess sustainability
aspects of ISFM interventions
4. ISFM and CA could be considered as covering different
phases along smallholder intensification pathways
And…
5. Creating an enabling environment for uptake of ISFM is
certainly as important as developing ISFM interventions
