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

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78

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28

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151617

18 19 20

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29 30

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3132

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67

1011

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13 1415 16

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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?