4. Soil Management For Cocoa

SOIL MANAGEMENT FOR SMALLHOLDER COCOA FARMERS IN VIETNAM Dr. S. Paramananthan (Soil Survey and Suitability Consultant)

Param Agricultural Soil Surveys (M) Sdn. Bhd. A4-3 Jalan 17/13, 46400 Petaling Jaya, Selangor, MALAYSIA

SUCCESS Alliance Vietnam: Establish smallholder cocoa in the four Vietnamese Provinces of Ben Tre, Tien Giang, Ba Ria Vung Tau and Binh Phuoc

SOIL MANAGEMENT FOR SMALLHOLDER COCOA FARMERS IN VIETNAM Objective: ● Improve quality and quantity of smallholder cocoa grown in South Vietnam ● Strength partnership between local government / universities / farmer groups / US and International private sector ● Sustainable development of cocoa smallholders industry Achieved through: ● Develop appropriate training protocols ● Develop core group of trainers to train farmers ● 17,000 smallholders over 7,500 ha (600 trees / ha)

SOIL MANAGEMENT FOR SMALLHOLDER COCOA FARMERS IN VIETNAM

SUCCESS Alliance hopes to achieve objective by: ● ● ● ● ●

establish cocoa clubs establish cocoa nurseries to supply seedlings establish model farms provide training and extention enhance capacity of local partners

SOIL MANAGEMENT FOR SMALLHOLDER COCOA FARMERS IN VIETNAM

Objectives of assignments: ● ● ● ●

Review soil under which cocoa is cultivated Propose a land evaluation system for cocoa Look at sustainability of soil health Provide training materials for extention workers

SOIL MANAGEMENT FOR SMALLHOLDER COCOA FARMERS IN VIETNAM

Smallholder Cocoa in South Vietnam ●

Cocoa cultivated under logans, coconut, cashew nut, durians

●

Farm Sizes ─ Ben Tre and Tien Giang ─ Ba Ria Vung Tau and Binh Phuoc

0.4-1.0 ha 1.0-1.5 ha

Location map of Ben Tre Province showing cocoa areas

Location map of Tien Giang Province showing cocoa areas

Location map of Ba Ria Vung Tau Province showing cocoa areas

Location map of Binh Phuoc Province showing cocoa areas

ENVIRONMENT ●

●

● ●

Topography and Elevation Ben Tre and Tien Giang ─ Mekong Delta ~ 1-2 metres asl. ─ Level (0-3° slopes) Ba Ria Vung Tau and Bin Phuoc ─ Upland areas (100-300 metres) ─ Level, undulating and rolling land (0-15° slopes) Geology and Geomorphology Ben Tre and Tien Giang ─ Estuarine deposits Ba Ria Vung Tau and Bin Phuoc

CLIMATIC ─ no reliable climatic data ●

Temperate: ─ Mean monthly temperature 24.5°29.3°C ─ Different summer / winter temperature < 5°C

●

Soil Temperature Regime (Soil Taxonomy) ─ Isohyperthermic

●

Rainfall: ─ 1,900 mm – 2,600 mm/annum ─ 3-5 dry (< 100 mm) months ─ Rains in Summer

Soil Moisture Regimes (Soil Taxonomy) ● Ben Tre and Tien Giang ─ Aquic ● Ba Ria Vung Tau and Binh Phuoc ─ Ustic

SOILS ● ● ●

Current Situation: Reconnaissance Soil Map / Report for Vietnam (1:1,000,000) Ben Tre and Tien Giang (1:250,000) ─ Mekong River Study Ba Ria Vung Tau / Binh Phuoc (1:100,000 scale maps)

► Reports in Vietnamese ► Soil Classification Systems ─ FAO/UNESCO Soil Map of the World (FAO, 1990) ─ Vietnamese System (based on FAO/UNESCO)

Soil map of Tien Giang and Ben Tre areas

Soil map of Ba Ria Vung Tau areas

Soil map of Binh Phuoc area

Physical and chemical characteristics of the major soil units (Ba Ria Vung Tau) Characteristic

Texture (%)

Colour (50 cm depth)

pH-H2O (Topsoil)

CECsoil (Topsoil) meq/100 g soil

Base Saturation %

Available P2O5 (ppm)

Organic Matter (Topsoil) %

Clay

Silt

Sand

Gravel

4

14

82

-

10YR5/4

5.64

4.83

46.38

2.6

0.69

25

9

66

-

10YR7/6

5.41

4.74

48.76

3.5

0.92

RhodiAcric Ferralsols

60

30

10

-

10R4/6

4.52

12.78

27.54

4.2

2.24

XanthiLixic Ferralsols

52

28

20

10-15

7.5YR4/6

5.76

16.53

62.92

8.4

1.72

Chromic Acrisols

18

32

50

-

7.5YR6/6

6.13

10.33

44.2

7.2

3.79

Soil Unit

Haplic Acrisols

Remarks

Physical and chemical characteristics of the major soil units (Binh Phuoc) Texture (%)

Characteristic

pH-H2O (Topsoil)

CECsoil (Topsoil) meq/100 g soil

Base Saturation %

Available P2O5 (ppm)

Organic Matter (Topsoil) %

Clay

Silt

Sand

Gravel

Colour (50 cm depth)

Haplic Acrisols

31-42

11-3

57-55

-

10YR6/3

4.60

12.7

19.7

11.2

3.00

Chromic Luvisols

31-35

18-16

51-49

50-80

10YR4/2

6.00

11.0

55.0

5.6-11.2

8.5

Rhodic Ferralsol (Fk)

47-46

23-27

29-26

-

2.5YR5/4

4.1

5.0

38.5

14.1-6.3

5.4

Xanthi-Acric Ferralsol (Fu)

39-49

1.5-15

45-35

10-15

7.5YR4/6

4.7

7.5

41.7

9.9-2.0

5.50

Skeleti-Chromic Acrisol (Fa)

27-40

15-13

57-46

50-60 below 50 cm

10YR7/6

5.00

6.0

33.3

4.3-2.0

3.8

Hapli-Chromic Acrisols (Fp)

29-37

10-4

61-57

8-10 (iron nodules)

7.5YR7/8

4.8

2.5

17.2

8.1-6.8

3.10

Gleyic Acrisol (Xg)

36

31

33

-

10YR8/2

4.9

6.87

35.3

Soil Unit

Remarks

High Iron (Fe)

High Iron (Fe) Mottled poor drainage

Hypothetical cross-section in the Ben Tre/Tien Giang areas

Dominant soils of Ba Ria Vung Tau and Binh Phuoc areas

The tentative classification of the major soils found in the Project Areas Province

Ben Tre and Tien Giang

Ba Ria Vung Tau

Binh Phuoc

FAO/UNESCO Soil Map of the World ― Revised Legend (FAO, 1990)

Soil Taxonomy ― Second Edition (Soil Survey Staff, 1999)

Vietnamese Soil Taxonomy

Dystric Fluvisols

Dystric Fluvaquents

na

Dystric Gleysols

Dystric Endoaquepts

na

Umbric Gleysols

Umbric Endoaquepts

na

Thionic Gleysols

Sulfic Endoaquepts Typic Sulfaquepts

na

Thionic Fluvisols

Sulfic Fluvaquents

na

Rhodic Ferralsols

Rhodic Haplustox

Rhodi-Acric Ferralsols

Haplic Ferralsols

Typic Haplustox

Xanthi-Acric Ferralsols

Haplic Acrisols

Typic Haplustult

Haplic Acrisols

Ferric Acrisols

Plinthc Haplustult

Ferric Acrisols

Rhodic Ferralsols

Rhodic Haplustox

Rhodi-Acric Ferralsols

Haplic Ferralsols

Typic Haplustox

Xanthi-Acric Ferralsols

Haplic Acrisols

Typic Haplustult

Haplic Acrisols

Ferric Acrisols

Plinthc Haplustult

Ferric Acrisols

LAND EVALUATION Edaphic factors important for cocoa are interrelated: ● Climate Factors ● Land Factors ● Soil Factors ― physical and chemical

Classification of soil nutrient status for cocoa Nutrient

Nutrient status Crops

Very low

Low

Moderate

High

Very high

pH

Cocoa

< 4.5

4.5–5.0

5.0–5.5

5.5–6.5

> 6.5

Organic C (%)

Cocoa

< 1.0

1.0–1.5

1.5–3.0

3.0–4.0

> 4.0

Total N (%)

Cocoa

< 0.10

0.10–0.15

0.15–0.25

0.25–0.40

> 0.40

Total P (µg g-1)

Cocoa

< 150

150–250

250–300

300–350

> 350

Available P (µg g-1)

Cocoa

< 10

10–15

15–25

25–35

> 35

Exchangeable K (cmol kg-1)

Cocoa

< 0.15

0.15–0.25

0.25–0.30

0.30–0.45

> 0.45

Exchangeable Mg (cmol kg-1)

Cocoa

< 0.15

0.15–0.25

0.25–0.40

0.40–3.00

> 3.0

CEC (cmol kg-1)

Cocoa

<8

8–12

12–15

12–25

> 25

Criteria for assessment of severity of soil limitations in cocoa SOIL PROPERTIES

Minor Limitation (S1)

Moderate Limitation (S2)

Serious limitation (S3)

Very serious  limitation (N)

CLIMATIC DATA (c) 1.

Mean annual max. temp. (°)

­28

28­30

30­32

33+

2.

Mean annual min. temp. (°)

+20

18­20

15­18

­15

3.

Total annual rainfall (mm)

1,400­2,500

1,200­1,400 2,500­3,500

<1,200 3,500­4,500

+4,500

4.

Length of dry season (months)

­2

2­3

3­4

4+

5.

Relative humidity (month with lowest value)

40­60

35­40 60­65

30­35 65­75

­30 +75

0–6

6–12

12–20

> 20

> 100

75­100

50­75

<50

0–5

5–20

20–40

> 40

friable– moderately firm

firm

very firm/loose

compact

sandy clay loam–clay

loam, fine sandy loam

coarse sandy loamy  sand

sand

well developed

moderately developed

very weak or massive

structureless

No peat

­

­

­

Moderately well to well  drained

imperfectly drained

poorly drained

very poorly  drained

75–100

50–75

25–50

< 25

low fertilizer  requirements

moderate fertilizer  requirements

high fertiliser   requirements

very high fertilizer  requirements

5.5–6.5

4.5–5.5

3.5–4.5

< 3.5

17. Conductivity (µmhos/cm)

< 500

500–1,000

1,000–2,000

> 2,000

18. Acid sulfate layer/Sulfidic layer (depth in  cm)

100+

75–100

50–75

< 25

TOPOGRAPHY (t) 6.

Terrain (°)

PHYSICAL SOIL CHARACTERISTICS (p) 7.

Effective soil depth (cm)

8.

Stoniness (%)

9.

Consistence

10. Texture 11. Structure 12. Peat (depth in cm) WETNESS CHARACTERISTICS (d) 13. Drainage class 14. Permanent water table (depth in cm) CHEMICAL CHARACTERISTICS (f) 15. Nutrient status 16. Soil pH

(Modified from Paramananthan, 1987 and Goh, 2002).

Evaluation of the Soil Map Unit 1

2

3

4

5

6

7

8

9

Dystric Fluvisol

Haplic Gleysol

Umbric Gleysol

Thionic Gleysol

Thionic Fluvisol

Rhodic Ferralsol

Haplic Ferralsol

Haplic Acrisol

Ferric Acrisol

1. Mean Annual Max. Temp. (°C)

S3

S3

S3

S3

S3

S2

S2

S2

S2

2. Mean Annual Min. Temp (°C)

S1

S1

S1

S1

S1

S1

S1

S1

S1

3. Total Annual Rainfall (mm)

S1

S1

S1

S1

S1

S1

S1

S1

S1

4. Length of Dry Season (month)

N

N

N

N

N

N

N

N

N

5. Relative Humidity (month with lowest value)

S1

S1

S1

S1

S1

S1

S1

S1

S1

S1

S1

S1

S1

S1

S2

S2

S1

S1

7. Effective Soil Depth (cm)

S1

S1

S1

S1

S1

S1

S1

S1

S2

8. Stoniness (%)

S1

S1

S1

S1

S1

S1

S1

S1

S1

9. Consistence (moist)

S1

S1

S1

S1

S1

S1

S1

S1

S1

10. Texture

S1

S1

S1

S1

S1

S1

S1

S1

S1

11. Structure

S2

S2

S2

S2

S2

S3

S3

S1

S1

12. Depth of Peat (cm)

S1

S1

S1

S1

S1

S1

S1

S1

S1

13. Drainage Class

S3

S3

S3

S3

S3

S1

S1

S1

S1

14. Permanent Watertable Depth (cm)

S2

S2

S2

S2

S2

S1

S1

S1

S1

15. Nutrient Status

S1

S1

S1

S2

S2

S3

S3

S3

S3

16. Soil pH - Water

S2

S2

S2

S3

S3

S2

S2

S2

S2

17. Conductivity (µmhos cm-1)

S1

S1

S1

S1

S3

S1

S1

S1

S1

18. Acid sulfate/Sulfidic layer depth (cm)

S2

S2

S2

S3

S3

S1

S1

S1

S1

Overall Current Suitability Rating

Nc

Nc

Nc

Nc

Nc

Nc

Nc

Nc

Nc

S2fp

S2fp

S2fp

S3fp

S3fp

S3f

S3f

S3f

S3f

CLIMATIC DATA (c)

TOPOGRAPHY (t) 6. Slope (°) PHYSICAL SOIL CHARACTERISICS (p)

WETNESS CHARACTERISTICS (w)

CHEMICAL CHARACTERISTICS (f)

Potential Suitability Rating Main Limitations Corrective Measures

Weak structures, acidic pH, acid sulfate conditions

Low nutrient retention, P-fixation, high porosity

Needs water control. Raising of beds, liming.

Managed mulching. Rock phosphate. Irrigation in dry season

FERTILISER REQUIREMENTS FOR COCOA

Amount of nutrients required depends on: ● ● ● ● ● ●

Types of planting materials Nursery practices ─ quality of seedlings Competition from other plants Shade regime and type of shade tree Rainfall as affecting soil moisture Soil factors ─ ability to supply and store nutrients

Nutrient uptake of cocoa (Ling, 1983)

Dry matter production and distribution in cocoa plants (Thong and Ng, 1978) % Distribution

Age of  plants  (months)

Total dry  matter  (kg/plant)

Leaves

Stem

Branches

Fruits

Roots

5

0.027

51.9

29.6

­

­

18.5

12

0.68

26.4

38.7

13.2

­

21.8

28

11.92

32.1

15.8

30.8

3.3

18.0

39

21.41

25.9

11.1

30.2

11.5

24.5

50

31.84

24.0

13.3

34.0

9.5

19.2

61

44.91

21.7

13.8

45.3

2.7

16.6

72

39.95

20.6

11.6

43.8

5.1

18.9

87

56.11

15.3

16.4

51.2

1.9

15.3

Nutrients immobilized in 5 year old cocoa (Ling, 1983) kg/ha

Nutrient

Munchong

Bungor

N

256

246

P

27

22

K

354

272

Mg

81

87

Ca

198

141

Dry Matter

27,775

25,830

Cocoa litter production and nutrient contents (Ling, 1983) Age (years)

Dry Matter (kg/ha)

N

P

K

Mg

Ca

4

2,538

38

2

33

15

30

6

5,032

80

4

80

28

67

8

4,560

72

4

81

27

56

10

5,556

87

5

91

31

71

kg/ha

Nutrients in pod production (Ling, 1983) Ages (years)

3

5

7

Dry Bean Yield (kg/ha)

kg Component

450

1,000

1,400

N

P

K

Mg

Ca

Beans

9.2

1.6

4.7

1.2

0.5

Husk

4.9

0.6

20.3

1.2

1.8

Total:

14.1

2.2

25.0

2.4

2.3

Beans

20.4

3.6

10.5

2.7

1.1

Husk

10.6

1.3

43.3

2.5

3.8

Total:

31.0

4.9

53.8

5.2

4.9

Beans

28.6

5.0

14.7

3.8

1.5

Husk

15.4

2.0

63.1

3.6

5.6

Total:

44.0

7.0

77.8

7.4

7.1

Effects of pod husks on soil chemical properties (0-15 cm) (Ling, 1983) Parameter

Treatment Without Pod Husks

Pod Husks (10 kg dry/tree)

pH

4.4

4.4

Total N (%)

0.139

0.138

Available P (ppm)

58

63

Organic Carbon (%)

1.13

1.35

Acid Ext. K (meg/100 g)

1.69

2.13

Acid Ext. Mg (meg/100 g)

0.95

0.99

Acid Ext. Ca (meg/100 g)

1.16

1.21

Classification of major leaf nutrient levels in cocoa (modified after Murray, 1966) Nutrient

% on D.M. Deficient

Low

Normal

N

< 1.80

1.8-2.0

> 2.00

P

< 0.13-0.15

0.15-0.20

> 0.20

K

< 1.20-1.40

1.40-2.00

> 2.00

Ca

< 0.30

0.30-0.50

> 0.50

Mg

< 0.20

0.20-0.45

> 0.45

Classification of minor leaf nutrient levels in cocoa (Southern and Dicks, 1969) Nutrient

ppm on D.M. Critical Level

Deficient Level

Mn

30

15

Fe

50

30

Zn

30

20

Cu

6

4

B

25

15

CHOICE OF SOURCE OF NUTRIENTS

●

Commercial ― cost

●

Organic source ― sustainable

Soil characteristics, limitations and management Region

Main Soil Characteristics • • •

Ben Tre and Tien Giang

• • • • • • • •

Ba Ria Vung Tau and Binh Phuoc

• • • • •

Main Soil Limitations

Estuarine deposits. Poorly drained silty clays to clays. Permanent watertable at 75 cm. Daily fluctuation of watertable. Acid sulfate conditions. Soils sticky when wet but hard when dry. Salinity levels. Fertility status moderate to high especially P and K (not in acid sulfate soils). Acidity.

•

Deep basaltic soils and alluvial soils. Excessive to moderately well drained. Slopes level to rolling. Heavy clay soils with high porosity. High iron content. Soils hard in dry season. Low fertility status.

• • • • • •

• • •

Long dry season (3-5 months). High watertables, sticky soils. High sulfides. Acidic soils.

Management Practices • • • • • • • • • •

Long dry season. High porosity. Soil erosion. P-fixation. Low fertility status. Termites.

• • • • • • • • •

Bunding and water control. Drainage with water control. Heap the soil around cocoa bush. Water management/heap the soil around base after leaching the soil. Liming. Heap after leaching out salinity. Moderate amounts of N. Organic matter mulching. Liming. Monitor fertility/pests and diseases. Irrigate soils in dry season. Mulch soils to retain moisture/nutrients. Mulch soils/stacking of branches. Rock phosphate application. Band placement. Organic manures. Return pods to field. Fertilizer applications. Eradicate termites.

RECOMMENDATIONS • Extension workers should know main soil types in the areas. • Copies of maps (soils etc.) should be made available in regional centres. • Notes on management. • Set up reliable climate station in major cocoa growing areas. • Field demo should be: correct/incorrect way of correcting problem. • Observation/trials using different techniques. • Characterize and analyse soils using standard international methods e.g. USDA’s Soil Taxonomy. • Produce detailed maps (1:25,000 or 1:5,000) of cocoa growing areas. • Compile data to prepare manuscript ‘Cocoa Growing Soils of South Vietnam ― Their Characteristics and

Thank you