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Agronomic Practices for Smallholder Cassava FarmersAgronomic Practices for Smallholder Cassava Farmers
Reinhardt Howeler and Tin Maung AyeAccra, October, 2010
Cassava yields can be increased by:Cassava yields can be increased by:
1. Planting of new varieties with higher yield potential, higher dry matter content, and pest/disease resistance
2. Improved crop management, especially soil fertility management
These two aspects are often of equal importance in increasing yields
Cassava yields in Thailand as affected by area under new varieties, Cassava yields in Thailand as affected by area under new varieties, fertilizer use and cassava root price 1990-2010fertilizer use and cassava root price 1990-2010
Year of harvest
Cassava area planted to
new varieties(%)
Cassava area receiving chem.
fertilizers(%)
Quantity of chem. fertil.
applied(kg/ha)
Cassava root
price (baht/t)
Average cassava yield (t/ha)
1990 1.1 13.91
1992 3.5 14.03
1995 23.8 1,620 13.02
1996 39.0 1,390 14.16
1998 80.8 1,780 14.93
1999 86.9 1,030 15.49
2000 91.1 850 16.86
2002 91.1 66.4 175 1,287 17.07
2003 97.9 56.2 172 1,061 19.30
2006 95.0 82.1 189 1,338 21.09
2007 94.6 79.9 197 1,753 22.92
2008 71.8 204 2,071 21.26
2009 70.3 229 1,668 22.68
2010 68.9 221 2,777 18.78
-50
0
50
100
150
200
1990 1992 1995 1996 1998 1999 2000 2002 2003 2006 2007 2008 2009 2010
Year of harvest
%% of cassava area planted to new varieties% yield increase since 1990
Trend in the percent of the total cassava area planted to new varieties and the percent yield increase in Thailand from 1990 to 2010 (2003 = 100%)
How can farmers increase their cassava yields in a sustainable
way?
To obtain high yields of cassavaTo obtain high yields of cassava
1. Plant high-yielding and well-adapted varieties
2. Use improved agronomic practices, such as:
- Correct time of planting and harvesting
- Use healthy and good-quality planting material
- Plant at the most appropriate planting distance
- Use adequate and well-balanced fertilization
- Have adequate and timely weed control
- Use effective erosion control practices (if needed)
- Use integrated pest and disease management (if necessary)
-
What is the best time to plant and to harvest cassava?
Cas
sava
root
yie
ld (t
/ha)
Effect of month of planting and age at harvest on root yields of cassava cultivars Rayong 2 and Rayong 3 planted at Rayong Field Crops Research Center in 1983-1985.Source: Field Crops Research Institute, Annual Report 1986.
12 months
10 months
8 months
6 months
Age at harvest
Rayong 2 (1984/85)
0
20
40
60
30
50
10
0
20
40
May June July Aug Sept Oct
Rayong 3 (1983/84 and 1984/85)
Month of planting
30
10
Land preparation
• Length 15-20 cm(7-10 nodes)
Planting stakes
• From stems of 8-12 months old plants• With diameter of 1.5-2.5 cm
Table 18. Plants survival (%) from stakes stored under different conditions and for various periods at Rayong Field Crops Research Center, 1976-1978. Storage time Storage method (days) Under shade In sun Covered with leaves 0 95.6 95.3 96.5 15 93.5 93.4 91.6 30 83.4 84.3 87.9 45 80.0 55.9 58.4 60 57.5 48.9 50.0 75 49.2 31.9 43.1 90 44.9 28.9 35.9 105 43.2 21.0 22.1 Source: Sinthuprama et al., 1984.
Cutting stems into stakes
Manual planting
Planting distance0.8 x 0.8 to 1 x 1 m
Mechanized planting
Rainy season planting
15
10
5
0
Cas
sava
root
yie
ld (t
/ha)
100
80
60
40
20
0
Ger
min
atio
n (%
)
Dry season planting
Weeks after planting
15
10
5
0
Cas
sava
root
yie
ld (t
/ha)
V I H
Vertical
InclinedHorizontal
Ger
min
atio
n (%
)
100
80
60
40
20
0 1 2 3 4
Response to N in Nanning, China
..to P and K in Xieng Khouang, Laos
..to K in Kampong Cham, Cambodia
Adequate and well-balanced fertilization depends on the crop
and the soil
0
10
20
30
40
0 40 80 160 0-0-0 80-40-80 160-80-1600 20 40 80 0 40 80 160
0 40 80 160 0 20 40 80 0 40 80 160 0-0-0 80-40-80 160-80-160
40 P2O580 K2O
40 P2O580 K2O
80 N80 K2O
80 N80 K2O
80 N40 P2O5
80 N40 P2O5
kg N/ha kg P2O5/ha kg K2O5/ha kg N-P2O5-K2O/ha
Star
ch c
onte
nt (%
)R
oot y
ield
(t/h
a)= KM 60 = SM 937-26
Effect of annual applications of various levels of N, P and K on the root yield and starch content of two cassava varieties grown in Hung Loc Center in Vietnam in
2007/08 (18th crop cycle)
After 31 years of continuous cropping in Khon Kaen, Thailand; without K in front, with well-balanced fertilizers in the back
In most soils in Asia, cassava needs
Or, a fertilizer ratio of 10-5-15
- Potassium
- Nitrogen
- Phosphorus
Be aware!
Cassava can cause serious soil erosion, even on gentle
slopes…..
….if large amounts of run-off water
accumulate in natural drainage ways
Soil loss by erosion can be a serious problem when the crop is planted on steep slopes
Fertilizer application improves canopy
development and is therefore one of the
most effective ways to reduce runoff and
erosion
Effect of various soil/crop management practices on the accumulative dry soil loss by erosion at the Royal Project site in Pluak Daeng, Rayong, Thailand during a ten month growth cycle of cassava in 1990/91.
0
200
400
J J A S O N D J F M A M
Rai
nfal
l (m
m)
0
5
10
15
20
25
30
Months after planting
Acc
umul
ativ
e dr
y so
il lo
ss (t
/ha)
2 4 6 8 100 12
no fertilizers
up-down ridging
1 plowing, 1 discing
cassava harvester
peanut intercrop
closer spacing
no tillage
contour ridging
Contour hedgerows of vetiver grass (in back) are
also very effective in reducing erosion
Trend in relative yield and relative soil loss by erosion when cassava was planted with contour hedgerows of vetiver grass, Leucaena leucocephala or Gliricidia sepium in comparison with the check without hedgerows during six consecutive years in Hung Loc Agric. Research Center in South Vietnam from 1997 to 2003.
0
20
40
60
80
100
120
140
160
180
200
1 2 3 4 5 6 7
check without hedgerows
Yield Soil lossVetiver =
Leucaena =Gliricidia =
Rel
ativ
e yi
eld
or so
il lo
ss (%
)
Year after planting hedgerows
Seven years after planting contour
hedgerows of vetiver grass in Hoa
Binh, these had caused the formation
of natural terraces which markedly
reduced erosion
….and after ten years in Khieu Thung, Phu Tho, Vietnam
Weed ControlCassava is a weak competitor,
and its growth and yield are seriously reduced by weed
competition
Cassava fields need to be weeded at least 2-3 times
during the crop cycle, usually at 1, 2 and 3 months
after planting
• Simple tools such as digging stick, hoe, or narrow spade
Root harvest
• Simple harvesting tools
The accidental introduction of the mealybug Phenacoccus manihoti into Thailand in 2008 has had a devastating effect on the whole cassava sector
…and a new witches broom-like disease in Vietnam
Integrated Pest and Disease Management in Cassava in Asia
1. Plant pest and disease resistant varieties
2. Treat planting material with insecticides/fungicides before planting
3. Burn all pest or disease–infected crop residues after harvest
4. Do not spray pesticides on the crop, but let biological control agents, such as the mealybug parasitoid Anagyrus lopezi, control the pest
Anagyrus lopezi
While many experiments have shown ways to increase yields, farmers seldom adopt improved
agronomic practices, because:
- they may not know the best and most efficient production practices- some recommended practices are not effective under the farmer’s particular conditions, or do not fit well in their farming systems- the recommended practices are too costly or too labor-intensive- they do not provide short-term economic benefits
To achieve impact through the adoption of improved practices
1. Farmers must be directly involved in the development of new varieties and improved agronomic practices that are most suitable and cost-effective for their own conditions
2. Researchers and extensionists should help farmers to conduct simple Farmer Participatory Research (FPR) trials on their own fields
3. These FPR trials should expand rapidly to as many villages and involve as many farmers as possible
4. Farmers are most likely to adopt those practices that other farmers have already tested , selected and adopted, i.e. farmer-to-farmer extension is an effective tool to achieve widespread adoption
04/07/23
Farmer Participationand Decision Making
Problem diagnosiswith farmers
Researchers show many technology options in FPR
demonstration plots
Feed back to researchAdopt and disseminate
Farmers adapt new practice and scale-up to
production field
Farmers retest and reselect
Farmers selectbest options
Farmers evaluate and select most suitableoptions/practices
Farmers test optionsin FPR trials on their own fields
Farmer Participatory Research (FPR) approach Farmer Participatory Research (FPR) approach
Using RRAs, we lUsing RRAs, we learnearneded about farmers’ conditions, needs and concerns about farmers’ conditions, needs and concerns
We set out demonstration plots and let farmers evaluate the various options and
select those that seem most promising
Farmers conduct FPR erosion control trials in
their own fields
….where they can
clearly see that some
simple practices can
markedly reduce runoff
and erosion
Farmers, researchers and extension workers evaluate the
treatments in all the FPR trials conducted in the village
Field day at time of harvest
After evaluating the trials in the field, farmers discuss the results together to select the best varieties and practices
Field day at time of harvest
1234
56
78
9
1011
12
13 14
•
28
27
25
26
151617
18 19 20
21 22 23
24
29 30
•
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3132
5
12
3 4
67
1011
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13 1415 16
9
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17 1819
2021
2223
24
282726
25 29
32 3130
3334
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2728 2930
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••
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Location of FPR pilot sites in China, Thailand and Vietnam in the Nippon Foundation cassava project in 2003.
Number of FPR trials conducted in the 2d phase of the Nippon Foundation Project in China, Thailand and Vietnam.
Country Type of FPR trial 1999 2000 2001 2002 2003 Total China Varieties 9 9 20 69 20 127 Erosion control 3 5 8 17 - 33 Fertilization - - - 4 - 4 Intercropping - - - 9 - 9 Pig feeding - - - 59 - 59 12 14 28 158 20 232 Thailand Varieties 11 16 16 19 25 87 Erosion control 14 10 6 - 11 41 Chemical fertilizers 16 6 23 17 17 79 Chem.+org fertilizers - - 10 11 11 32 Green manures - - 13 11 15 39 Weed control - - 17 5 10 32 Plant spacing - - 3 - 2 5 Intercropping - - 16 7 - 23 41 32 104 70 91 338 Vietnam Varieties 12 31 36 47 35 161 Erosion control 16 28 29 30 23 126 Fertilization 1 23 36 24 24 108 Intercropping - 14 32 31 26 103 Weed control - 3 - - 3 6 Plant spacing - 1 7 19 8 35 Leaf production - - 2 2 1 5 Pig feeding - - 11 16 13 40 29 100 153 169 133 584 Total 82 146 285 397 244 1,154
Thong Nhat commune in North Vietnam in 1998
Serious erosion problems and low yields of cassava
and tea
The Impact!!The Impact!!
Thong Nhat commune in North Vietnam in 2000
A farmer proudly shows off his “new cassava” field
Figure 1. Average cassava yields of farmers participating in the Nippon Foundation cassava project or of nearby but non-participating farmers, before the project started and at the end of the project. Data are from PRRA census forms collected from 439 households in Thailand and 393 household in Vietnam. For comparison the national average cassava yields in 1999 (before) and 2003 (after) are also shown
= Project participants= Non - participants= All country (1999-2003)
Beforeproject
Beforeproject
Afterproject
0
5
10
15
20
25
30
Afterproject
0
5
10
15
20
25
30Thailand Vietnam
Cas
sava
yie
ld (t
/ha)
Figure 1. Trend of cassava yields in Africa, Latin America and Asia from 1961 to 2007.
Year
20
1960
18
16
14
12
10
8
6
4
2
01970 1980 1990 2000 2010
Cas
sava
yie
ld (t
/ha)
Asia
Americas
Africa
20
18
16
14
12
10
8
6
4
2
0
Helping farmers to conduct simple FPR trials on their own fields is the best way to achieve adoption of improved varieties and agronomic
practices that will increase cassava yields and farmer’s income
Is this going to
be the future of
our children?
…….or can we help cassava farmers improve their liveliho
od by producing enough food AND feedstock for starch
and biofuel?