Presentation on cassava

1. Cassava
What do we know about the crop?
Stefan Hauser, Root & Tuber Crop Systems Agronomist

2. Total Nigeria
Soil management nutrient supply 81 55
Soil management intercropping 29 19
Soil management tillage 12 8
Soil management green manure 6 4
Soil management mulch 5 5
Soil management alley cropping 12 8
Crop management 30 22
Pest & disease management 6 1
Climate 1 1
182 123
What has been published?

3. What is IITA working on in the Agronomy and
Natural Resource Management domain?
RTB – Root & Tuber Agronomy:
Effect of compost lime and fertilizer on leaf an root yields of 3 cassava varieties.
Effect of planting sick size and position and fertilizer application on germination and root
yield of two cassava varieties.
Effect of fallow type, biomass management and fertilizer on cassava root yield in
Cameroon .
SARD SC:
Root yield response of 9 cassava varieties to fertilizer and leaf harvest .
Root yield response of 6 cassava varieties to fertilizer and different leaf harvest intensities
CRP Maize:
Compatibility of maize and cassava varieties for intercropping and effects of fertilizer and
leaf harvest in DR Congo
These are the small ones . . . . .

4. Sustainable Weed Management in Cassava
Systems:
Agronomic measures to reduce weed pressure,
effects of reduced weeding and weeding method
and mechanical weeding options

5. African Cassava Agronomy Initiative
demand-driven development of agronomy interventions,
focusing on specific needs of development and
private sector partners.

6. ACAI (African Cassava Agronomy Initiative):
Linked to input supply and fertilizer industry
• Site-specific fertilizer recommendations
• New fertilizer blends optimized for cassava production in
major cassava-growing areas
General for all cassava growers
• Best planting practices (tillage, density, fertilizer application)
• Optimal intercropping practices (focus on maize in Nigeria)
Linked to output markets
• More continuous supply to processing factories by staggering
planting and harvesting
• Increased starch yields (higher DM and starch content)
Cassava agronomy technology options: 6 use cases

7. Why now on-farm cassava
agronomy trials?
YIELD
In cassava we may
well look at a yield
gap equivalent to
90% of the yield
potential.
80 Mg ha-1 fresh
roots are often
quoted as a potential
but on single plant
basis 120 Mg ha-1 are
possible.

8. Currently the focus in research
is still on germplasm improvement.
Certainly important but
will not solve production
problems in the long term

9. Yield of improved vs local
cassava varieties
 CNN reported 50 t/ha by Zimbabwean farmers in Kwara State, Nigeria
Edo
Bayelsa
Cross River
Akwa Ibom
Ebonyi
Enugu
Anambra
Imo
Rivers
Delta
Abia
Yield across States (t/ha)
0 5 1510 20 25 30 35
Improved varieties
Local varieties

10. Some of the reasons are:
•Bad misconceptions of crop requirements (cassava),
•Low level of mechanization,
•Soil degradation, unsuitable tillage systems
•Lack of reliable recommendations on fertilizer use,
•Unavailability of suitable herbicides,
•Insufficient knowledge on the crops’ responses to
intercrops
•Insufficient knowledge on profitable input use (economics)
•Low level of intensification,
•Small scale production,

11. Source df SS P>F SS P>F SS P>F
Loc 13 971721 <0.0001 35920 <0.0001 5871 <0.0001
Fert 1 1448 0.0963 359 0.0001 0.7 0.8178
Loc*Fert 13 21722 <0.0001 1740 <0.0001 112 0.0229
Clone 42 198689 <0.0001 6107 <0.0001 3576 <0.0001
Fert*Clone 42 11123 0.9964 674 0.9537 870 0.0027
R-square 0.6886 0.6378 0.6838
CV 31.83 26.84 10.29
Root number Fresh yield (t/ha) Dry matter (%)
Fertilizer response, 14 locations, 200 kg/ha NPK
0
10
20
30
40
50
60
70
80
90
100
4(2)1425
82/00058
91/02324
92/0057
92/0067
92/0325
92/0326
92B/00061
92B/00068
94/0026
94/0039
94/0561
95/0166
95/0289
95/0379
96/0523
96/0603
96/1089A
96/1565
96/1569
96/1632
96/1642
97/0162
97/0211
97/2205
97/3200
97/4763
97/4769
97/4779
98/0002
98/0505
98/0510
98/0581
98/2101
98/2226
99/2123
99/3073
99/6012
M98/0028
M98/0040
M98/0068
TME419
TMS30572
PercentchangeinFreshrootyield
18.8271
17.8915
17.4
17.6
17.8
18
18.2
18.4
18.6
18.8
19
F NF
Freshyield(t/ha)
LSD = 0.57
Percent change: 5.23
0.0
Significant
interactions
indicating
differential response
of varieties to
location and
fertilizer
18.8
17.9

12. 111
222
333
444
18
36
54
72
95
190
285
380
0
50
100
150
200
250
300
350
400
450
5 10 15 20 25 30 35 40 45
Root DM yield (Mg ha-1
)
Nutrientuptake(kgha
-1
)
N
P
K
Current potential yield equivalent
to 80-90 Mg ha-1
fresh roots
Which nutrients and how much is required?

13. What went wrong?
What goes wrong?

14. The actual heterogeneity of a cassava
population (plot or treatment) is rather high in
both, above ground mass and tuberised root
mass.
Individual cassava plants separated into leaf bearing branches stem and roots, Kiyaka, Nov. 2011

15. 0
0.1
0.2
0.3
0.4
0.5
0.6
0.7
0.8
0.9
1
0 10 20 30 40 50 60 70 80 90 100
Percent plants
Relativecontributiontoyield
Cultivar Zizila,
12 MAP, leaves not harvested,
Mvuazi, Bas Congo
Relative contribution to the yield of individual plants of a cassava variety
in DR Congo planted at 1 x 1m (10000 ha-1).
87.7% of root mass deemed suitable,
11.56 Mg ha-1 fresh roots

16. Variety Sadisa, 12 MAP, Kiyaka, Bandundu, DR Congo
Root fresh mass = 1.26 stem & leaf fresh mass
r
2
= 0.8625, N=192
0
2000
4000
6000
8000
10000
12000
0 1000 2000 3000 4000 5000 6000 7000 8000
Stem and leaf fresh mass
Rootfreshmass
Sadisa, 12 MAP, 22.6 Mg ha-1

17. Root fresh mass = 1.127 stem & leaf fresh mass
r2
= 0.78, N = 215
0
2000
4000
6000
8000
10000
12000
0 1000 2000 3000 4000 5000 6000 7000 8000 9000
Stem & leaf mass (g)
Rootfreshmass(g)
TME 419, 12 MAP, 32.1 Mg ha-1

18. Secondary tuberous roots of
various sizes
Roots like pearls on a string
Not to talk about the
shape and size

19. Data on single factor effects and
interactions on weed abundance and
biomass and cassava yields

20. 0
5
10
15
20
25
Variety Site System Tillage Fertilizer
Cassavafreshrootyield(Mgha-1)
TME 419
Intercrop
Ido
Moniya
TMS 30572
Monocrop Ridged
Flat
Fertilizer
Nil
p<0.0013 p<0.0163
p<0.0001p<0.0001
p<0.0001
Cassava root yields 1st season
Useful cassava fresh root yield by factor in a first season planted cassava crop.

21. 0
5
10
15
20
25
Usefulcassavafreshrootyield(Mgha-1)
Monocrop
Ido
Moniya
Intercrop
TMS 30572
TME 419 Ridged
FlatNil
Fertilizer
p<0.0001
p=0.001
p<0.0001
p<0.0001
p<0.0013
Useful cassava fresh root yield by factor in a second season planted cassava crop.
System Site Variety Fertilizer Tillage
Cassava root yields 1st season

22. 0
5
10
15
20
25
30
35
0 20 40 60 80 100 120 140 160 180 200
Cassavafreshrootyield(Mg/ha)
Moniya 2 Ido 2
Moniya 1 Ido 1
mean 15.0
mean 18.1
114 plots, equiv. to 59.4% larger than
the National average (12.5 Mg/ha)
173 plots, equiv. to 90.1% larger than
the National average (12.5 Mg/ha)
Yield distribution in 1st and 2nd season at Moniya and Ido

23. 0
10000
20000
30000
40000
50000
60000
70000
0 500 1000 1500 2000 2500 3000
Usefulcassavafreshrootyield(Kgha-1)
Sequential plot number in descending order of yield
1st season
2nd season
Double Nationalaverage
25000 Kg ha-1
Nationalaverage
12500 Kg ha-1
Mean 13380 Kg ha-1
Mean 16150 Kg ha-1
Yield distribution in 1st and 2nd
season at 15 sites in Nigeria

24. ?

25. The IITA Agronomy Laboratory at Mampu,
DR Congo

26. www.iita.orgA member of CGIAR consortium
26
Clearly - there is no shortage of open questions in
cassava agronomy and crop husbandry in SSA.
Conclusion
Thank you