1. 1
Maximizing returns to fertilizer
use on maize in Malawi
Lessons from on-farm agronomic research
Farm Input Subsidy Program (FISP)
National Symposium
14-15 July 2014
Lilongwe, Malawi
Todd Benson
IFPRI

2. 2
How can farmers derive maximum
benefits from using fertilizer on
maize? Presentation outline
 Nationwide on-farm fertilizer trials on hybrid maize
 Activity of the Maize Productivity Task Force of the
Ministry of Agriculture in 1995/96 and 1997/98
 Results - agronomic response in Malawi
 kg maize per kg fertilizer (or kg N) applied
 Optimal crop management practices

3. 3
Area-specific fertilizer
recommendations trials, 1995/96 &
1997/98 Single-replicate trials run by
extension FAs
 Plot treatments were fertilizer
packages – bags of fertilizer
per ha
 Six treatments in 95/96;
Four in 97/98
 Urea, 23:21:0+4S, &
DAP (DAP in 95/96 only)
 Second year trial signboard here
 MH17 or MH18 hybrid maize

4. 4
Area-specific fertilizer
recommendations trials, 1995/96 &
1997/98 Planted on farmer’s field
 Farmer managed, with
supervision by FA
 Good, consistent crop
management
 Site selection protocols to
avoid confounding factors
 Pests, Striga, frequent flooding
 Plots not fertilized previous
year
 Successful - Obtained data for
analysis from 83% of sites in first
year, 70% in second year

5. 5
Agronomic results
 Strong yield response in
maize to fertilizer
 Nitrogen is most limiting nutrient
for maize production
 Yield response to phosphorus
varies from area to area
 Generally significant responses
to sulphur
 National quadratic N-
response pattern across the
two years shown here
 In analysis, adjusted trial plot yield
values downward to better reflect
likely crop performance on larger
fields
0
500
1000
1500
2000
2500
3000
3500
0 25 50 75 100 125
Maizeyield(kg/ha)
Nitrogen (kg/ha)
Y = 1286+ 29.7N– 0.122 N2

6. 6
Agronomic results
 17.7 kg maize per kg N-
applied
 National average linear hybrid
maize yield response
 7.0 to 9.5 kg grain per kg
fertilizer (urea & 23:21:0+4S)
 Highest responses seen in
upland areas
 Lowest response in Lower
Shire Valley
 But highest yields without fertilizer
 Lakeshore – intermediate and
more varied
N-response
(linear)
kg maize per
kgN
Intercept
(no N)
kg maize
per ha
National 17.7 1,430
Karonga ADD 14.4 1,620
Mzuzu ADD 19.0 1,110
Kasungu ADD 19.0 1,330
Lilongwe ADD 19.3 1,440
Salima ADD 19.1 1,550
Machinga ADD 17.8 1,290
Blantyre ADD 17.7 1,600
Shire Valley ADD 11.7 1,860
Note: ADD – Agricultural Development Division

7. 7
Phosphorus and Sulphur
 Nitrogen single most
important nutrient limiting
maize yields in Malawi
 However, response to
phosphorus and sulphur
over wide areas
 1995/96 trial results
provided insights here
 However, note this is an
agronomic assessment
 Annual use of P & S
fertilizers may not
necessarily make
economic sense for farmer
 In any case, apply with
nitrogen
Mzuzu
Lilongwe
Blantyre
Zomba
Karonga
Salima
Kasungu
Mchinji
Chitipa
Nsanje
Mangochi
Mzimba
No significant response
Signific ant response
Zo nes of response to thea pplication of
in maize at moderate
levels of nitrogen.
,phosphorus and sulphur
Comparison of 35:10:0+ 2S
(kg N:P0 :K+ S
per ha).
2 5
versus35:0:0
Mzuzu
Lilongwe
Blantyre
Zomba
Karonga
Salima
Kasungu
Mchinji
Chitipa
Nsanje
Mangochi
Mzimba
No significant response
Signific ant response
Comparison of 96:40:0
versus 92:21:0+ 4S.
Zones of response to the
appli cation of
in maize when
nitrogen and
phosp horus are
notlimi ted.
,sulphur

8. 8
Optimal crop management
practices Agronomic ‘rules of thumb’ for profitable and
efficient fertilizer use on maize
 Regardless of how much fertilizer is applied,
farmers must do a good job in growing maize
 Use fresh hybrid seed adapted for local conditions
 Plant as early as possible
 Apply fertilizer on time
 Basal dressing immediately after emergence
 Apply top-dressing 3 to 4 weeks later
 Any further delay and nitrogen in fertilizer increasingly goes to
produce stover, not grain

9. 9
Agronomic ‘rules of thumb’
(cont.) Weed well
 1996/97 demonstration on this
point at 118 sites
 Weeding twice with half
fertilizer (Trt 2) gives about
same yield as weeding once
with full rate (Trt 3)
 Economically, net benefits of
Trt 2 higher than Trt 3
 Reflecting cheaper cost of
labour for weeding relative to
cost of fertilizer
0
1000
2000
3000
4000
Trt 1 Trt 2 Trt 3 Trt 4
maizeyield(kg/ha)
Trt 1 Weed once
Apply half recommended fertilizer
Trt 2 Weed twice
Apply half recommended fertilizer
Trt 3 Weed once
Apply all recommended fertilizer
Trt 4 Weed twice
Apply all recommended fertilizer

10. 10
Agronomic ‘rules of thumb’
(cont.) Application methods
 1996/97 demonstration at 318
sites to compare methods
 Expected to see no difference in
yields, but not the case
 Dolloping superior
 No statistical yield difference
between banding and
broadcasting
 However, labour requirements
differ between methods
 When labour constrained,
economically could make sense
to broadcast
0
1000
2000
3000
4000
B
anding
D
ollopingB
roadcasting
maizeyield(kg/ha)
Banding Sprinkled in groove on side
of ridge
Dolloping Two holes 10 cm from
planting station
Broadcasting Spread evenly on ridge top;
follow with weeding to
cover with soil

11. 11
Agronomic ‘rules of thumb’
(cont.) Soil and within-field variations
 Soil texture useful indicator of fertilizer response
 Sandy soils typically less fertile, so respond well to
fertilizer when growing conditions are good
 Medium-textured soils not as responsive to fertilizer as
light-textured soils, but typically less risky
 Less affected by drought. Fertilizer does not leach from them
as much under heavy rains
 “The best and worst parts of a field should not
receive fertilizer”
 Best areas – locally fertile patches – not very responsive
 Worst areas – other problem than soil fertility limit maize
yields – termites, Striga (kaufiti), waterlogging, etc.

12. 12
Organic strategies for soil fertility
management
 Organic residue use reduces need for inorganic fertilizers
 Not all organic sources of value
 Grain legume crop residues, khola manure, compost, &
prunings from N-fixing shrubs and trees generally good
 Maize stover generally not recommended
 Grain legume rotations
 At higher N:maize price ratios (>4.5), grain legume-maize
rotations (e.g., groundnut, soyabean) often provide better
financial returns over 2 years than fertilized maize alone
 Best rotation crop with maize for soil fertility and
increased maize yield is kalongonda (velvetbean)

13. Implications for FISP design
 Efficient logistics
 Timeliness in crop operations is a big part of efficient
production
 Agronomic information to FISP beneficiaries
 Extension component to FISP
 Many farmers know as much about making effective use of
fertilizer as do researchers, but many do not
 Targeting
 Can identify areas where greater returns from applying
fertilizer to hybrid maize can be obtained
 Can identify beneficiaries who have assets or labour that
will enable higher returns to fertilizer use
13