Integrated Soil Fertility Management

(ISFM) in Sub-Saharan Africa:

Concepts and practice

Bernard Vanlauwe

International Institute of Tropical Agriculture (IITA)

Nairobi, Kenya

b.vanlauwe@cgiar.org

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