Cassava is a versatile crop that has several uses in the African context. It can withstand the harshest growing conditions and still yield considerably as compared to other food crops.
When it comes to rating, it falls third after rice and maize for our staple food sources in Africa. Nutritionally, cassava is rich in carbohydrates, making it one of the best energy sources. Cassava leaves are highly nutritious and contain high protein levels — ranging from 16.6 per cent to 39.9 per cent as reported by Khieu et al., 2005 — and mineral levels, as well as being a valuable source of vitamins B1, B2 and C and carotenes.
It has also been reported that the leaves can rival alfalfa on amino acid concentration and can be used as an animal feed supplement. When using cassava leaves, farmers are advised to harvest them within the fourth and fifth months to avoid affecting the tuber underground as it relies on the photosynthesis that occurs on the leaves for growth. Also as the leaves age, the nutrient levels decrease.
For optimal cassava production, farmers should adopt the following technologies, innovations and management practices famously abbreviated as TIMPS:
1. Selection of Appropriate Variety (Planting Material)
The selection of the right variety for your agro-ecological zone is critical for the success of any crop. Farmers have the habit of borrowing seeds from each other after seeing how a particular crop flourishes in a farm one could have visited for training or other activities especially if they are in different regions. One should always compare the weather patterns of the two regions to estimate whether the said crop will be successful in your own area. However, should you not have that information, your local extension officer can avail it including varieties best-suited for your area.
In Kenya, the following cassava varieties have been made available through Kenya Agricultural and Livestock Research Organisation (Kalro) and Kenya Plant Health Inspectorate Service (Kephis).
2. Propagation and Planting
Cassava is grown from stem cuttings of mature healthy plants between 12 and 18 months old. The stem cuttings can be sourced from credible sources like Kalro centres or from commercial seedling/ planting material providers or from successful cassava farmers near you. When sourcing for planting material, make sure the source has clean-disease and pest-free stem cuttings.
The stem cuttings should be the length of one ruler (30 cm) and 2 cm to 2.5 cm thick (slightly bigger than a candle). It should also have five to eight nodes and be selected from the centre of the stem. The planting method that works best is vertical planting especially in dry areas with low soil moisture and lots of heat from the sun. In such areas, the bigger part of the stem cutting should be buried in the soil to encourage deep root formation.
Cassava-spacing depends on the farming system adopted: such as mono-crop or intercrop. Always ensure that you plant the stem cuttings as soon as you can. Do not store them out for too long as it reduces their viability. If forced to store them, avoid direct sunlight, hot and cold winds. Store them with the buds facing upwards and avoid too much movement that causes bruises on the stem cuttings.
3. Husbandry (Soils, water management, weeds, pests and disease control)
Cassava is a fairly low maintenance crop in terms of crop husbandry practices like crop nutrition and one can produce cassava with zero input. However, for optimal production, it is best that farmers practice soil nutrition, water management, weed, pests and disease control practices that aid the production of the crop. The main cassava diseases in Africa are the African cassava mosaic disease (ACMD) and cassava brown streak disease (CBSD). The best way of controlling the diseases is prevention through sourcing clean disease tolerant/ resistant planting material. Once it affects your farm, remove the affected plants and burn them. Also, control pests that act as carriers/vectors of said diseases. Intercropping or rotating cassava with other crops also helps control diseases and pests as well.
Always keep your cassava farm weed-free. One can achieve this through mulching which will in turn control loss of soil moisture and soil erosion. It is also advised that during land preparation, add well-decomposed farmyard manure and wood ash to supplement other micronutrients in the soil.
If left for too long, cassava tubers become woody and unsuitable for human consumption. Farmers, therefore, need to harvest the crop as soon as it reaches maturity as guided by the variety chosen. The harvesting plans should be pegged on the purpose of the crop as the tubers do not keep well for long. It takes a maximum of three days for them to go bad. When harvesting, farmers should consider access to the market or other value addition activities available. For mass markets one can harvest all the crops at once through uprooting whereas for piecemeal farmers should harvest in portions.
Value addition activities that help cassava last longer include, drying the tubers and converting them to flour or dry cassava cuts, making cassava chips, ethanol or starch. Value-addition extends the storage life of the tuber to give farmers time to source for better markets and better prices.