I set off to the South of Rwanda, from Kigali, the capital, on the road to Muhanga District near the Burundi border.
My destination is Vunga, a hilly village. The village is in the lowlands and a little bit warmer with a rich brown soil.
A few metres off the main highway, I get to the homestead of Drocella Yankulige, a mother of seven. Her house is modest, and she beams with life and pride, as her grandson Blaise Arakabaho, 11, rides a bicycle in the compound.
The house is connected to the national electricity grid. Life seems good for Drocella.
Later, she smiles as she proudly says, “All that you see in this home is from sweet potato.”
Drocella supplies to other farmers orange-fleshed sweet potato planting materials. Orange-fleshed means the variety has been fortified with Vitamin A.
It is this crop that fully employs Drocella. Every three to four months, she makes 700,000 Rwanda Francs (RWF), which is about Sh100,000. With three seasons in a year, her take home is Sh300,000 from sweet potatoes vines and tubers that she sells to Sina Gerard Ltd, a company that buys the later for extracting puree (from the Orange Fleshed Sweet Potatoes), used in making biscuits, mandazi and bread. The value addition is what is putting money into pockets of millions of Rwandese farmers.
She plants the crop, which is the second most important in the country after cassava, on 1.5ha of her land every season, with each costing 10 RWF or a 1kg at 150 RWF.
The Rwanda Agricultural Board (RAB) provides her with clean planting materials.
“With the growing demand for vines, and tubers for use in adding value to biscuits and bread, I have been forced to hire more land for planting sweet potatoes,” says the 55-year-old.
To plant the crop, one prepares beds and plants the vines 30cm between plants by 80cm from one row to another. She uses organic farm yard manure to grow the tubers. However, in cases where inorganic fertiliser has to be used, phosphorus and potassium-based fertiliser are applied. Nitrogen-based fertiliser is discouraged as it enhances growth of leaves, neglecting the tubers.
Drocella plants five varieties, some which are available in Kenya and they include Kabonde, Orange Fleshed Sweet potatoes, Gihingumukungu, Terimbere and Cacearpedo.
She harvests the tubers after every three to four months depending on the variety. At four months, however, that’s the best time for making puree.
Dr Geraldine Mukeshimana, Rwanda’s Minister for Agriculture and Animal Resources, says farmers in the country produce over 941,000 metric tonnes of sweet potatoes annually or 88kg per capita.
“The fact that sweet potato produces lots of tubers in a small area is its true strength and the reason it is so critical to our food security,” the official says.
Drocella is a tech–savvy farmer. In her house sits a laptop, which she uses to record data from her improvised sweet potato store, also known as Zero Energy Sweet Potato Cool Storage Unit, which is widely adopted in Rwanda.
The cooler has two walls, the outer and inside one made of bricks.
The inner wall, however, is shorter. The roof is made of tiles and ceilings bamboo.
Between the two walls, there is space filled with charcoal that is watered three times a week to keep the facility cool. There are five basins of water inside the unit to help cool it as the moisture eveporates. Charcoal is an ideal material for refrigeration because it has pores, which absorb and store water. This reduces heat from outside. And because wet charcoal does not allow easy passage of heat, it results into low temperature inside the cubicle.
Inside the store, wooden shelves hold the sweet potatoes of different varieties separately. Drocella will sell them to different customers depending on their preferences. The store has two special thermometers, which take the temperatures inside and outside and transmit them to a software in a laptop to give readings of the changes. If the temperature is high, the farmer adds water to the charcoal, thus, enabling the potatoes to remain fresh up to six months.
“Through this, a farmer is able to know the time when the temperatures are high, guiding on the times to pour water on the charcoal for cooling the unit to enable the produce remain fresh,” says Jean Claude Nshimiyimana, an agronomist at the International Potato Centre, which offers farmers growing the crop technical advice.
Nshimiyimana says the zero energy store has extended considerably the shelf-life of the sweet potatoes.
Farmers have an option of selling their produce in the market or storing seeds for the following season. “With the store, Rwandese farmers are not affected by glut, which often leads to low prices in the markets,” he says.
For Drocella, with the zero-energy store, she has enough to eat and sell within the seasons, giving her a source of income all-year round.
Her main challenge was how to water her vines during the dry season. To mitigate this, she bought a manual water pump for irrigation.
Diseases that affect the tubers
Diseases to guard against are sweet potato feathery mottle virus and sweet potato chlorotic stunt virus. A combination of these two is what causes the biggest damage. The farmer uses negative selection to remove diseased plants. Negative selection is where a farmer uproots diseased plants leaving the healthy ones to thrive. Most diseases are spread by insects.
Lack of Vitamin A in the body has been known to cause blindness, disease and premature death in sub Saharan Africa. One medium-size sweet potato provides enough daily allowance beta carotene, which is converted into Vitamin A for lactating mothers and children.
which pass pathogens from the diseased to the healthy.