The ManicaPost
Samuel Kadungure
Senior Reporter
IN the face of climate change shocks — food, nutrition and livelihoods security — can be attained if farmers diversify their cropping to include sweet potato, given its great potential as a crop for consumption and source of income.
Kutsaga regional sales agronomist, Mr Itai Mazhangara singled out sweet potato because they are easy to grow, require few inputs and are relatively drought resistant.
With agriculture deeply dependent on weather, regional weather and climate experts this seasons predicted an El Niño phenomenon that increases the likelihood of below-normal rainfall conditions, and resultantly trigger negative impacts such as dry spells and droughts, making sweet potato a crop of choice to achieve food security in the face of climate change.
Mr Mazhangara said because most farmers grow maize under rain-fed agriculture, such a monoculture may become vulnerable to drought, and only crop diversification can help agricultural systems adapt to climate change, warmer and drier climates.
“Such crop diversification will help increase farmers’ incomes and improve nutritional outcomes as well as help the county to become more resilient to climate shocks. Sweet potato is a popular and traditional food crop whose advantages include minimal disease and pest problems, short season requirement, easy to grow and grows in a wide range of soils. It is an excellent source of carbohydrates, vitamin A, carotene, calcium, phosphorus, thiamine and iron,” he said.
He said markets are fast opening up in Japan and China after some organisations expressed interest in buying sweet potatoes from Manicaland.
Sweet potatoes are mainly grown in Chipinge and Makoni districts, and the province usually comes third after Mashonaland East and Midlands in terms of production capacity.
This position shows that Manicaland has huge potential in exporting sweet potatoes, especially if farmers concentrate on viable varieties such as yellow-fleshed one.
“Sweet potatoes can be grown in a wide range of soils, but the best soil types should be well-drained, fine sandy or clay loams. The sweet potato plant does not thrive on highly acid soils and the most desirable pH range is between 5,0 and 6,5.
“On soils with a pH below 5,0, lime must be applied and dolomitic limestone should be given preference. Soil testing is recommended before planting and this can be done at Kutsaga Research Station at a nominal cost,” said Mr Mazhangara.
He said the crop can be planted throughout the year, but the ideal planting time for maximum yield is at the onset of the rainy season or immediately after the rainy season when soil is still moist.
Sweet potato can be propagated from tissue culture plantlets, small tuber sprouts or vine cuttings (slips).
“Select healthy, vigorous slips free from pests and diseases. Planting material available to most sweet potato farmers is often of poor quality, but pest and disease-free sweet potato plantlets and vines can be obtained at Kutsaga Research Station.
“These plantlets are produced through tissue culture in the laboratory which ensures elimination of insect pests and disease pathogens.
“The vines are produced hygienically in the greenhouse. Every sweet potato grower should therefore strive to get this type of material every three years for sustained yields,” he said.
Mr Mazhangara said there are processing and consumption varieties of sweet potato.
Processing varieties include alisha, delivia, beaurigard and brontal, while chigovha, Mozambique and Germany 2 are ideal for consumption.
Mr Mazhangara said planting can be done on flat land in furrows and later mounds can be constructed to facilitate good tuber growth.
“The optimum plant population is 40 000 per hectare. Terminal cuttings/slips tend to produce the highest yields. Early planting is recommended for lower rainfall areas (less than 800mm).
“On farms with irrigation and no frost occurrence, production can be done all-year round. When irrigation is used, avoid overwatering at later growth stages because this results in extensive vine growth at the expense of tuber development.
“The recommended fertiliser rate will depend on soil analysis, however, as a general recommendation, apply 300 kg per hectare of compound ‘D’ (7:14:7) at planting or the alternative, double ‘D’ (14:28:14) at 150kg per hectare.
“The use of compost or organic fertilisers is highly recommended. Moderate amounts of nitrogen are required as excessive amounts may encourage rank growth and result in cracked and misshapen roots and poor storage quality. Apply up to 100kg AN/ha at or before 45 days after planting,” he said.
