Cassava (Manihot esculenta) is an increasingly important crop for food security, smallholder income, and industrial starch production in South Africa. Although traditionally grown on a limited scale, cassava has strong potential in warm, frost-free regions of the country due to its drought tolerance, adaptability to poor soils, and diverse uses. This guide provides South African farmers with a comprehensive, practical overview of cassava production, based on national production guidelines and local growing conditions.
1. Introduction to Cassava
Botanical Classification
- Scientific name: Manihot esculenta
- Family: Euphorbiaceae
- Common names: Cassava (English), Mutumbula (Tshivenda), Muthupula (Xitsonga), Unjumbula (isiZulu)
Origin and Distribution
Cassava originated in South America and was introduced to Africa by Portuguese traders in the 16th and 17th centuries. It spread rapidly across tropical Africa and today is a staple crop in many countries. Globally, Nigeria and the Democratic Republic of Congo are among the largest producers, while Thailand is the world’s leading exporter of dried cassava.
Cassava Production in South Africa
In South Africa, cassava is grown mainly as a secondary crop by smallholder farmers, with commercial production focused on starch for industrial and food use. Approximately 20 000 tons of cassava starch are produced annually. Major production areas include:
- Limpopo (largest producer)
- Mpumalanga
- Northern KwaZulu-Natal
2. Cassava Varieties
Cassava is broadly classified into two types:
- Sweet cassava: Lower cyanogenic content, higher yields, more commonly grown
- Bitter cassava: Higher cyanogenic content, mainly used for industrial processing
In local markets, varieties are often distinguished by the colour and texture of the root peel rather than formal cultivar names. Farmers are encouraged to use high-yielding, disease-resistant planting material sourced from healthy fields.
3. Plant Description
Cassava is a perennial shrub that grows up to 2.4 metres tall under cultivation.
- Roots: Tuberous, long and tapered, with white or yellowish flesh rich in starch. Tubers contain calcium, phosphorus and vitamin C but are low in protein.
- Stems: Erect, branching, containing milky latex.
- Leaves: Large, palmate leaves with 5–7 lobes, borne at the ends of branches.
- Flowers and fruit: Male and female flowers occur on the same plant. The fruit is a small capsule containing three seeds.
The economically important parts of the plant are the tubers and leaves.
4. Climatic Requirements
Temperature
Cassava is a tropical crop that performs best in frost-free areas.
- Growth stops below 10°C
- Optimal temperatures: 25–29°C
- Best yields occur below 150 m altitude, though some varieties grow up to 1 500 m
Cassava is a short-day plant; excessive day length can delay tuber formation.
Rainfall and Water
- Optimal rainfall: Well-distributed rainfall
- Tolerates 500–5 000 mm per year
- Highly drought tolerant
During drought, cassava sheds older leaves to conserve water and resumes growth when moisture returns, making it ideal for areas with unreliable rainfall.
5. Soil Requirements
Cassava grows well on a wide range of soils, provided they are well-drained and friable.
- Best soils: Light sandy loams and loamy sands
- Tolerates poor and depleted soils
- Avoid waterlogged or flood-prone areas
On very fertile soils, excessive leaf growth may occur at the expense of tuber development.
6. Cultivation Practices
Propagation
Cassava is propagated exclusively using stem cuttings taken from healthy, disease-free plants. This ensures uniformity and higher yields compared to seed propagation.
Land Preparation
- First-time cultivation on cleared land requires minimal preparation
- Previously cropped land should be ploughed 2–3 times to remove weeds
- Deep ploughing improves tuber development
Burning of cleared vegetation can help control pests and release potassium, but excessive burning may reduce long-term soil fertility.
Field Layout and Spacing
- Avoid slopes steeper than 8%
- Ensure good drainage
- Row spacing: 80–100 cm
- In-row spacing: 80–100 cm
- Plant population: 10 000–15 000 plants per hectare
Plant across slopes or along contours to reduce soil erosion.
7. Planting Systems
Cassava can be:
- Grown as a sole crop
- Intercropped with maize, legumes, vegetables, oil palms or rubber
Intercropping reduces risk and maximises land use. Cassava is often planted as an intercrop initially and later becomes a sole crop after the companion crop is harvested.
8. Fertilisation and Soil Nutrition
Cassava has high nutrient requirements, especially when grown continuously.
A crop yielding 25 t/ha removes approximately:
- 60 kg Nitrogen (N)
- 40 kg Phosphorus (P₂O₅)
- 136 kg Potassium (K₂O)
Key Points:
- Potassium promotes starch formation
- Nitrogen and phosphorus support growth
- Excess nitrogen leads to leaf growth with poor tuber yields
Soil analysis is strongly recommended to determine fertiliser requirements. Smallholders commonly use cattle or poultry manure.
9. Irrigation
Cassava is rarely irrigated due to its drought tolerance, but:
- Regular watering improves yields
- Avoid complete soil drying during early growth
10. Weed, Pest and Disease Control
Weed Control
- First weeding: 3–4 weeks after planting
- Second weeding: 1–2 months later
- Earth up plants during weeding to encourage tuber formation
Pests
- Insects: locusts, beetles, ants, aphids
- Animals: rats, goats, wild pigs
Diseases
Common diseases include:
- Cassava mosaic disease
- Bacterial blight
- Anthracnose
- Root rot
Control measures:
- Use clean planting material
- Destroy infected plants
- Avoid poorly drained fields
- Plant resistant varieties where available
11. Harvesting
Maturity
- Harvesting period: 6 months to 3 years, depending on variety and use
- Optimal starch yield: 18–20 months
Delaying harvest too long can lead to lignification, making roots woody and less suitable for consumption or processing.
Harvesting Methods
- Mostly manual
- Plants are topped 40–60 cm above ground
- Tubers are pulled or dug out carefully to avoid damage
Cassava does not lend itself easily to mechanised harvesting due to deep and widespread tuber growth.
12. Post-Harvest Handling
Cassava deteriorates rapidly after harvest.
- Must be processed within 48 hours
- Cannot be stored fresh for more than 2 days
Processing Steps
- Washing and peeling
- Rasping or grating
- Starch extraction by sedimentation or centrifuge
- Drying (solar or artificial)
- Milling and packaging
By-products such as peels and fibre can be used as animal feed or fertiliser.
13. Marketing and Utilisation
Uses
- Staple food (boiled, baked or fried)
- Leaves and shoots as vegetables
- Animal feed
- Industrial starch for food, paper, textiles, pharmaceuticals and adhesives
- Alcohol production
Cassava must always be cooked or processed to reduce cyanogenic compounds.
Marketing
Because fresh cassava is bulky and perishable:
- Most processing is done on-farm
- Products such as gari, lafun and fufu have longer shelf life
- Markets include local communities and neighbouring countries such as Eswatini and Mozambique
Cassava offers South African farmers a resilient, versatile crop well suited to warm regions with variable rainfall. With proper variety selection, soil management, and timely processing, cassava can contribute meaningfully to household food security, livestock feeding, and agro-industrial value chains.
For farmers seeking to diversify production or utilise marginal land, cassava remains a crop of strategic importance for the future of South African agriculture.
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