What you need to know:
- With new varieties that mature in about eight months now available, growing cassava should not be a tedious task.
Cassava is an important food security crop in northern Uganda. It is estimated that 74 percent of farming households in Uganda grow cassava mostly as an intercrop.
Cassava has numerous advantages including producing the highest amount of starch compared to other crops yet it can grow under marginal environmental conditions with limited inputs. Inorganic fertiliser is the most highly recommended in cassava production.
But farmers in northern Uganda are faced with a major challenge of cassava mosaic and cassava brown streak diseases.
Ngetta Zonal Agricultural Research and Development Institute (Ngetta Zardi) has revealed a high prevalence of the disease in northern Uganda since 2015 triggering research into resistant varieties.
To reduce the impact of the diseases, Ngetta Zardi in partnership with the Agricultural Technology Agribusiness and Advisory Services (ATAAS) project work hand in hand to promote adoption of tolerant cassava varieties.
Angella Kyobutungi, a crop technician at the institute explains that making farmers aware of the improved agronomic practices can make cassava farming more profitable.
“Having clean planting materials and proper field hygiene can help maximise cassava production,” Kyobutungi says.
Kyobutungi was the facilitator on cassava agronomy at the Seeds of Gold Farm Clinic in Lira. She explains that much as cassava is a hardy crop, it requires specific care.
Cassava can almost grow in every soil type apart from stony or shallow soils, extremely sandy, salt affected, clayey or waterlogged soils. An area infested with spear grass is also not ideal because the Imperata rhizomes can cause rot when they penetrate cassava tubers.
Care should be taken while choosing planting materials to avoid the spread of diseases such as cassava mosaic and cassava brown streak.
“Therefore, farmers need clean planting materials. They should also avoid using contaminated cutting implements,” Kyobutungi cautions.
She cautions that before one embarks on growing cassava on a commercial level, Kyobutungi says farmers should understand the available market and what it requires.
“Understanding market requirements is important in cassava production. The main market is for fresh roots and processed products. Growing for the market makes farming profitable,” she explains.
She emphasises that the market dictates so many things including the mode of harvesting and equipment needed at harvest time.
Kyobutungi stresses the importance of spacing as being crucial. The currently recommended spacing is a square arrangement, 1x1m, that is to say one cassava plant per square metre. This gives 10,000 plants per hectare.
Cassava can be planted as an intercrop with either legumes, melons, yams or maize. In this case, the recommended optimal planting density for maize is 40,000–50,000 maize plants per hectare. It is advised that maize is planted at 20cm linear spacing with one plant per stand to avoid clusters of several maize plants in the same stand. Kyobutungi says that generally the intercrops are planted first before cassava.
Under normal conditions, about 90 percent of all cassava cuttings should sprout within two weeks of planting. Cuttings that do not sprout should be removed and disposed of away from the cropping area in order to prevent the transmission of any diseases that may have caused the failure of the cuttings.
During the growing phase, cassava requires little or no pest and disease management, but should receive timely attention on weed control.
Weeds compete with crops and can retard their growth while reducing the performance of cassava.
She explains that a well-weeded cassava garden can yield 30–40 percent more roots than a poorly weeded farm.
It should be noted that weed control forms a significant part (30-50 percent) of the labour costs in cassava production.
Weeding frequency will depend mostly on the type and severity of the local weed problem, but generally it is important to start weeding 3–4 weeks after planting. Weeding should be repeated in weeks 8 and 12, while the final weeding should be done between 20 and 24 weeks after planting, depending on the rainfall
To increase production, Kyobutungi explains that fertilisers can be applied.
She says that applying nutrients to the soil enables the maintenance of soil health and improves depleted or poor soils. Nutrient depletion normally occurs after land has been under continuous cultivation for many years.
She recommends use of inorganic fertilisers but by using chemical fertiliser on their cassava, smallholder farmers can increase their yields from about 10 to 16 tonnes fresh roots per hectare.
She cautions that the right fertiliser should be applied at the right time, rate and method.
Research has established that for every one tonne of cassava roots harvested, about 2.3 kilogrammes of nitrogen (N), 0.4 kilogramme of phosphorus (P) and 3kg of potassium (K) are removed from the soil. This implies that an average harvest of 10 tonnes of roots removes 23kg N, 4kg P and 30 kg K.
She says that the application of nutrients helps to replace the lost nutrients and maintain soil fertility to enable continuous good yields in subsequent farming seasons. “Fertiliser can only make sense if it is profitable. Farmers should not rush into fertiliser application before calculating the estimated cost,” she cautions.
She says that one should be able to calculate the change in yield brought about by use of fertiliser, how much the yield is worth and the amount of money required to purchase fertiliser.
Cassava can be harvested by numerous methods including by hand or mechanical harvesting tools which have been developed.
Each cassava stand will need to produce an average of 1.6 kg of useful roots to generate 16 tonnes of fresh cassava roots per hectare. When processed this will yield about 3–4 tonnes of edible dry matter.
Kyobutungi explains that by using simple tools such as cassava chippers farmers can reap more benefits. The chipper makes it possible for cassava to dry in a matter of hours.
“The benefits are immense as the quality of the cassava flour is high grade,” she explains.