Consortium for the
improvement of agriculturebased livelihoods in
Central Africa
The potential of
Integrated Soil Fertility Management
for increasing cassava productivity in
sub-Saharan Africa
B Vanlauwe, P Pypers, N Sanginga
TSBF-CIAT, Nairobi, Kenya
Consortium for the
improvement of agriculturebased livelihoods in
Central Africa
Context of African agriculture
1. Farming in SSA…
LACK OF PRODUCTION FACTORS
 High input prices
(1 kg of NPK in East DR Congo costs 1.7 USD)
 Recycling of organic residues, mainly manure
(but very limited availability)
 Limited labor availability
(HIV-AIDS, drudgery, low appeal for young people, etc)
 Relatively small farms on relatively old soils
LACK OF AN ENABLING ENVIRONMENT
 Lack of infrastructure, market organization
 Civil strife
 Climate change, etc, etc,…
Context
Facts
ISFM
Progress
Concl
2. Variability!  Continental scale
Soils in East and Central Africa
Context
Facts
ISFM
Progress
Concl
2. Variability!  At the farm scale
Context
Facts
ISFM
Progress
Concl
2. Variability!  At the farm scale
Context
Facts
ISFM
Progress
Concl
2. Variability!  At the farm scale
Context
Facts
ISFM
Progress
Concl
3. The opportunity…
 Finally, fertilizer and inputs are back on the agenda!
Statement in 1996 (Research Director, IITA):
‘You can’t include fertilizer in your work since
farmers in SSA are not using fertilizer’
 The African Fertilizer Summit declaration:
‘By 2015, increase fertilizer use from 8 to 50 kg
fertilizer nutrients/ha’
 The Alliance for a Green Revolution in Africa
Uniquely African (K Annan): ‘Recognizing its great
diversity of landscapes, soils, climates, and cultures…’
Context
Facts
ISFM
Progress
Concl
Consortium for the
improvement of agriculturebased livelihoods in
Central Africa
Facts about cassava
1. Cassava supports ± 25% of farming households in
SSA (± 100 mill people) and is a major crop on ± 35%
of all agricultural land (± 60 mill ha)
Context
Facts
ISFM
Progress
Concl
2. Cassava production is increasing but mainly due to
area expansion
120,000,000
area
12,000,000
100,000,000
production
10,000,000
80,000,000
8,000,000
60,000,000
6,000,000
40,000,000
4,000,000
20,000,000
2,000,000
0
1960
Context
1965
1970
Facts
1975
1980
1985
ISFM
1990
1995
2000
Total production (metric ton)
Total area under cassava (ha)
14,000,000
0
2005
Progress
Concl
3. Cassava productivity is low in SSA
25,000
Thailand
Brasil
Nigeria
DR Congo
Cassava yield (kg/ha)
20,000
15,000
10,000
5,000
1960
Context
1965
1970
Facts
1975
1980
ISFM
1985
1990
1995
2000
Progress
2005
Concl
4. Cassava is exporting substantial amounts of nutrients
(mainly K) but requires N and K to grow
Nutrient uptake and removal - Macronutrients
Y
Plant
t/ha
Source
45
Amarasiri,
1975
Fresh roots
Whole plant
37
Fresh roots
Whole plant
18
Fresh roots
Whole plant
kg/ha
Howeler,
1985
Sittibusaya,
Pers comm
NPK ratio for roots:
NPK ratio for whole plants:
Context
Facts
N
P
K
62
10
164
202
32
286
67
17
101
198
31
183
32
3
34
95
10
64
5 : 1 :10
7:1: 7
ISFM
Progress
Concl
5. Soil fertility management in cassava systems is very
much under-researched in SSA relative to other regions
Production (2004)
12000
(www.fao.org)
 SSA:
 LatAm:
 Asia:
 World:
Number of abstracts
10000
8000
108 mill ton
35
60
203
6000
4000
All
Sub-saharan Africa
< 30%
2000
< 5%
< 2%
0
Cassava
Context
Facts
Cassava and soil
ISFM
Cassava and fertilizer
Progress
Concl
Consortium for the
improvement of agriculturebased livelihoods in
Central Africa
Integrated Soil Fertility Mgt
ISFM…
Paradigm
1960s/70s
Role of fertilizer
Use of fertilizer alone
will improve and
sustain yields
Role of organic inputs Experiences
Organic resources
Limited
play a minimal role
success due
to shortfalls
1980s
Fertilizer plays a
minimal role
1990s
Fertilizer use is
essential to alleviate
the main nutrient
constraints
2000s
Fertilizer is a major
entry point
Organic resources
are the main source
of nutrients
Organic resources
are the entry point
and provide other
functions besides
nutrient release
Proper management
of crop residues
External Input
Paradigm
‘1st Paradigm’
Organic Input
Paradigm
Sanchez’
‘2nd Paradigm’
Integrated Soil
Fertility
Management
Context
Facts
ISFM
Progress
Limited
adoption
Difficulties to
access
organic
resources
On-going;
several
examples of
good
potential
Concl
ISFM…
‘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 of
improved germplasm’
Agronomic efficiency =
[Increase in yield]/[Fertilizer nutrient applied]
Context
Facts
ISFM
Progress
Concl
Yield/ Agronomic efficiency
in
e
e as
e
g
d
le
w
k no
r
c
n
I
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
Site-specific responses to fertilizer
Context
Facts
ISFM
Progress
Concl
Yield/ Agronomic efficiency
in
e
e as
e
g
d
le
w
k no
r
c
n
I
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
Yield/ Agronomic efficiency
in
e
e as
e
g
d
le
w
k no
r
c
n
I
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
Yield/ Agronomic efficiency
e
‘Quick
g
d
le
w
approaches’
no
k
- Flyersse in
akits
e
r
-IDemo
nc
- Focus on access
- Etc
A
Start scaling
up today
C
Medium term
involvement
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
Facts
‘Complex
approaches’
- Farmer
field schools
- Extension
expertise
- Etc
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
Consortium for the
improvement of agriculturebased livelihoods in
Central Africa
ISFM and cassava
Agronomic efficiency
Inc
r
in
e
s
ea
w
o
n
k
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
e
g
d
le
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
Agronomic efficiency
STEP 1: Germplasm and fertilizer
Inc
r
in
e
s
ea
w
o
n
k
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
e
g
d
le
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
STEP 1: Germplasm and fertilizer – WE KNOW…
1. Improved varieties (eg, CMD-resistant) are essential
to obtain substantial yield increases; supply needs to
match demand by a healthy crop
local variety
Context
improved variety (Nsansi)
Facts
ISFM
Progress
Concl
STEP 1: Germplasm and fertilizer – WE KNOW…
2. Cassava responds to fertilizer
CIALCA trials in Sud-Kivu, DR Congo
without
fertilizer
Context
with fertilizer
(2 bags of NPK ha-1)
Facts
ISFM
Progress
Concl
STEP 1: Germplasm and fertilizer – WE KNOW…
2. Cassava responds to fertilizer but minimum benefits
are needed to justify its usage
CIALCA trials, Sud-Kivu, DR Congo
Estimated
production
(kg fresh
roots/ha)
Manure at 5
t/ha (local
practice)
Manure (5
t/ha) + NPK
(100 kg/ha)
Context
Extra costs Benefits from Marfor fertilizer
fertilizer
ginal
application
application rate of
(USD/ha)
(USD/ha)
return
2,500 15,000
--
--
--
5,000 25,000
170
300 -1,600
1.8-9.4
Facts
ISFM
Progress
Concl
STEP 1: Germplasm and fertilizer – WE KNOW…
3. Fertilizer management affects its use efficiency
30
25
20
15
10
5
Context
Facts
ISFM
FYMSF/ASGerm
FYMINC/ASBanded
FYM-ASSF
0
FYM-ASINC
Fertilizer recovery (%)
Fertilizer recovery by maize
Progress
Concl
STEP 1: Germplasm and fertilizer – DO WE KNOW?
1. Optimal application rates for specific soils and AEZs?
(Current recommendations are based on info from Asia!)
Economically optimal response
Yield
Inputs
Context
Facts
ISFM
Progress
Concl
STEP 1: Germplasm and fertilizer – DO WE KNOW?
1. Optimal application rates for specific soils and AEZs?
(Current recommendations are based on info from Asia!)
2. Best fertilizer type for specific soils?
(Different soils have different nutrient supply capacities!)
Context
Facts
ISFM
Progress
Concl
STEP 1: Germplasm and fertilizer – DO WE KNOW?
1. Optimal application rates for specific soils and AEZs?
(Current recommendations are based on info from Asia!)
2. Best fertilizer type for specific soils?
(Different soils have different nutrient supply capacities!)
3. Appropriate management of fertilizer relative to land
preparation (flat, ridges, mounds, etc) and placement
(point-placed, broadcast, etc)?
(Proper fertilizer management has been shown to affect
its use efficiency by other crops)
Context
Facts
ISFM
Progress
Concl
STEP 1: Germplasm and fertilizer – DO WE KNOW?
1. Optimal application rates for specific soils and AEZs?
(Current recommendations are based on info from Asia!)
2. Best fertilizer type for specific soils?
(Different soils have different nutrient supply capacities!)
3. Appropriate management of fertilizer relative to land
preparation (flat, ridges, mounds, etc) and placement
(point-placed, broadcast, etc)?
(Proper fertilizer management has been shown to affect
is use efficiency by other crops)
4. Fertilizer application and tuber quality?
(Cassava+, etc)
Context
Facts
ISFM
Progress
Concl
Agronomic efficiency
STEP 2: Germpl/fert + OM mgt
Inc
r
in
e
s
ea
w
o
n
k
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
e
g
d
le
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
STEP 2: Germpl/fert + OM mgt – WE KNOW…
1. Organic resources are best produced in-situ and with
multiple purposes for farmers to be interested
Dual purpose soybean in west Kenya
Context
Facts
ISFM
Progress
Concl
STEP 3: Gpl/fert + OM mgt + Loc adapt – WE KNOW…
2. Cassava-based system are sufficiently flexible to
integrate various grain legumes
Cassava-groundnut
intercropping in
Bas-Congo, DRC
Context
Facts
Cassava-cowpea
intercropping in
Bas-Congo, DRC
ISFM
Cassava-beans
Intercropping
In Sud-Kivu, DRC
Progress
Concl
STEP 3: Gpl/fert + OM mgt + Loc adapt – WE KNOW…
2. Cassava-based system are sufficiently flexible to
integrate various grain legumes
legume grain yield (kg ha-1)
CIALCA trials in Sud-Kivu, DRC
improved variety
2500
2000
1500
1000
local variety
500
0
cassava
spacing
Context
-
-
-
-
fertilizer
-
fertilizer
-
-
-
-
-
2nd
legume
2nd
legume
local
1x1
1x1
2x0.5
2x0.5
2x0.5
2x0.5
Facts
ISFM
Progress
Concl
STEP 2: Germpl/fert + OM mgt – WE KNOW…
3. Organic resources contain nutrients that can benefit
cassava but their contents are most often limited for
commonly available resources
50
Tithonia(80K)+fertilizer(40K)
Chromolaena(80K)+fertilizer(40K)
tuber yield (kg FW ha-1)
40
fertilizer(120K)
30
20
control
10
0
Mbuela
Context
Facts
MbanzaNzundu
ISFM
Progress
Concl
STEP 2: Germpl/fert + OM mgt – DO WE KNOW?
1. Do organic inputs provide other functions than
substituting fertilizer nutrients that will favor cassava
productivity (e.g., reduce P sorption, buffer Al toxicity)?
Context
Facts
ISFM
Progress
Concl
STEP 2: Germpl/fert + OM mgt – DO WE KNOW?
1. Do organic inputs provide other functions than
substituting fertilizer nutrients that will favor cassava
productivity (e.g., reduce P sorption, buffer Al toxicity)?
2. For maize, the combined application of organic matter
and fertilizer can create added benefits that can lead to
improved use efficiency of the fertilizer and/or the organic
inputs for maize which is most responsive to N and P.
What for cassava, which is more responsive to K?
Context
Facts
ISFM
Progress
Concl
STEP 2: Germpl/fert + OM mgt – DO WE KNOW?
1. Do organic inputs provide other functions than
substituting fertilizer nutrients that will favor cassava
productivity (e.g., reduce P sorption, buffer Al toxicity)?
2. For maize, the combined application of organic matter
and fertilizer can create added benefits that can lead to
improved use efficiency of the fertilizer and/or the organic
inputs for maize which is most responsive to N and P.
What for cassava, which is most responsive to K?
3. Which measures are needed to restore productivity
on degraded, non-responsive sites?
Context
Facts
ISFM
Progress
Concl
STEP 2: Germpl/fert + OM mgt – DO WE KNOW?
1. Do organic inputs provide other functions than
substituting fertilizer nutrients that will favor cassava
productivity (e.g., reduce P sorption, buffer Al toxicity)?
2. For maize, the combined application of organic matter
and fertilizer can create added benefits that can lead to
improved use efficiency of the fertilizer and/or the organic
inputs for maize which is most responsive to N and P.
What for cassava, which is most responsive to K?
3. Which measures are needed to restore productivity
on degraded, non-responsive sites?
4. Cassava leaves contain a lot of N; could a wellmanaged cassava crop be an entry point to boost
overall system productivity?
Context
Facts
ISFM
Progress
Concl
Agronomic efficiency
STEP 3: Gpl/fert + OM mgt + Loc adapt
Inc
r
in
e
s
ea
w
o
n
k
A
C
Responsive soils
Poor, less-responsive soils
B
Current
practice
Germplasm
& fertilizer
Germplasm
& fertilizer’
+ Organic
resource mgt
Move towards ISFM
Context
e
g
d
le
Facts
ISFM
Germplasm
& fertilizer
+ Organic
resource mgt
+ Local
adaptation
‘Full ISFM’
Progress
Concl
STEP 3: Gpl/fert + OM mgt + Loc adapt – WE KNOW…
1. Soil physical management for cassava production
as a function of soil depth, slope, and moisture status
Bas-Congo
Context
Sud-Kivu
Facts
ISFM
Progress
Concl
STEP 3: Gpl/fert + OM mgt + Loc adapt – WE KNOW…
2. Responses to fertilizer are variable
CIALCA trials in Bas-Congo, DRC
50
Mbuela
tuber yield (kg FW ha-1)
Mbanza Nzundu
40
SED
30
20
10
0
0
50
100
150
200
250
fertilizer application rate (kg K ha-1)
Context
Facts
ISFM
Progress
Concl
STEP 3: Gpl/fert + OM mgt + Loc adapt – DO WE KNOW?
1. Local diagnosis of soil fertility status?
(Farmers seem to have an idea but will this be sufficient as
a basis for recommendations?)
Organic C measurements
Farmer class
Low
Medium
High
Low
Medium
High
57%
22%
18%
33%
61%
34%
10%
17%
48%
Context
Facts
ISFM
Progress
Concl
STEP 3: Gpl/fert + OM mgt + Loc adapt – DO WE KNOW?
1. Local diagnosis of soil fertility status?
(Farmers seem to have an idea but will this be sufficient as
a basis for recommendations?)
2. Fertilizer placement relative to rainfall and physical
soil preparation (ridges, mounds, etc)?
(Consider soils and roots for optimal recovery)
Context
Facts
ISFM
Progress
Concl
Consortium for the
improvement of agriculturebased livelihoods in
Central Africa
Conclusions
1. Are cassava-based systems amenable to ‘full’ ISFM?
 Most likely yes
(All steps are potentially relevant for cassava-based
systems, but substantial knowledge gaps exist)
Context
Facts
ISFM
Progress
Concl
2. Is cassava an entry point for soil fertility rehabilitation?
 Leaves contain a lot of nutrients; ‘N-sparing’ effects
have been demonstrated for crops following cassava
(This would only be valid if the cassava itself is showing
a relatively high productivity)
 In agronomic terms, cassava allows intercropping of
various other crops, including legumes
(These legumes could replenish the soil N stocks, improve
the soil P status, etc)
 It is unsure whether cassava would be a good crop
on non-responsive plots that are being rehabilitated
Context
Facts
ISFM
Progress
Concl.
3. Are cassava-based systems ready to join the
scaling up investments of AGRA?
 Yes, for the germplasm component
(Activities are on-going to disseminate germplasm)
 Probably yes for the fertilizer component
(Avoid applying fertilizer where it wouldn’t work)
 Probably not for full ISFM dissemination
(While knowledge on cassava-based systems is
generated, other AGRA investments will address issues
related to availability of inputs, access to markets, etc)
Context
Facts
ISFM
Progress
Concl.
Bedankt!
Merci beaucoup!
Thanks!
Asante sana!