Sweet Potato Cultivation in Bangladesh: BARI Varieties, Planting, Fertiliser and Storage

On the char lands of Jamalpur, sweet potato has turned into a crop farmers count on. In January 2024 The Daily Star's Bengali edition reported that a farmer in Sarishabari upazila had spent 15,000 taka on one bigha and lifted about 90 maunds of sweet potato, at a time when the crop was selling for 1,200 to 1,400 taka a maund. The Department of Agricultural Extension (DAE) expected the district to produce 29,510 tonnes that season.

Yet across Bangladesh sweet potato is still treated as a minor crop, and most fields yield far less than the improved varieties can give. This guide explains what the crop is, how much of it Bangladesh grows, which varieties the Bangladesh Agricultural Research Institute (BARI) has released, and how to plant, feed, water, protect, harvest and store it. Every rate and figure is given as the DAE, BARI scientists or another named authority states it.

The sweet potato (Ipomoea batatas) belongs to the morning glory family, Convolvulaceae. It is a herbaceous perennial vine whose stems creep along the ground and put out roots at the nodes. Its large, starchy, sweet tuberous roots are eaten as a vegetable, and the young shoots and leaves are sometimes eaten as greens. Despite the name, it is only distantly related to the common potato.

The crop is native to tropical South America and spread across the world, usually carried as vine cuttings rather than seed. It became a common food crop in the Pacific islands, South India, Uganda and other African countries.

According to FAOSTAT figures for 2020, the world produced 89.5 million tonnes of sweet potato that year, and China alone grew 48.9 million tonnes. Malawi, Tanzania, Angola and Ethiopia followed. A 2016 study in the journal Foods by researchers at the University of Dhaka described sweet potato as the seventh most important food crop in the world and the fourth most important crop in Bangladesh, after rice, wheat and potato.

Sweet potato is also more than food for people. A 2023 study by BARI's Tuber Crops Research Centre noted that the crop can be used as animal fodder and can be processed into breads, french fries, syrup, starch and beverages.

The DAE's crop sheet for sweet potato on its Bangladesh Agro-Meteorological Information Service (BAMIS) portal gives its food value. Every 100 grams of the edible part contains:

• 68.5 grams of water and 1.0 gram of minerals
• 0.8 grams of fibre and 120 kilocalories of food energy
• 1.2 grams of protein, 0.3 grams of fat and 28.2 grams of carbohydrate
• 20 milligrams of calcium
• 0.06 milligrams of vitamin B1, 0.02 milligrams of vitamin B2 and 2 milligrams of vitamin C

Orange-fleshed varieties add one more benefit. The International Potato Center (CIP) describes orange-fleshed sweet potato as an excellent source of vitamin A, which is essential for the health and development of pregnant women and children. The 2016 Foods study recorded that in Bangladesh about one million children showed clinical signs of vitamin A deficiency and that 30,000 children became blind every year. Anyone worried about a child's diet or eyesight should see a doctor.

The BARI team that published in the journal Heliyon in July 2023 reported that the country's sweet potato production rose by 15.70 percent between 2018-19 and 2020-21, reaching 279,800 tonnes. Over the same period the area under the crop grew by 13.20 percent, from 23,024 hectares to 26,528 hectares.

The same study pointed to a wide gap between what farmers harvest and what the crop can give. The average yield stood at around 10.50 tonnes per hectare, while estimates put the achievable yield at up to 40 tonnes per hectare.

District reports from before 2025 show where the crop is growing. In Jamalpur, The Daily Star reported in January 2024 that farmers had planted sweet potato on 43 hectares more than the DAE's target. The varieties named there included BARI-2, BARI-3, BARI-4, BARI-8, BARI-9 and BARI-14, along with Kamala Sundari, Tripti and Japanese varieties such as Okinawa and Murasaki. The deputy director of the DAE in Jamalpur, Zakia Sultana, said the area's soil and weather suited the crop.

In Gobindganj upazila of Gaibandha, the Daily Ittefaq reported in April 2021 that sweet potato covered 85 hectares that year, on sandy land along the Bangali river. Nine acres were planted with a Japanese variety under the government's Tuber Crops Development Project, and the upazila agriculture officer said farmers were getting 20 tonnes per hectare. A company was buying the crop from the fields for export to Japan.

Development groups have also pushed the crop. In November 2020 The Financial Express reported that 6,000 farmers in Gaibandha, Kurigram and Rangpur were growing orange-fleshed sweet potato on 909 bighas, using BARI SP-4, BARI SP-8 and BARI SP-12. In its 2021 annual report, CIP said that almost 50,000 land-poor households in Bangladesh began growing sweet potato between 2019 and 2021, and that 283 trained vine growers had sold 29 million vine cuttings, enough to cover 500 hectares.

Improved varieties yield far more than local ones, and the first two BARI varieties showed this early. In an on-farm trial in greater Noakhali in the 1986-87 rabi season, reported at the Bangladesh Science Conference in 1988, Kamala Sundari yielded 34.2 and 34.45 tonnes per hectare at the two sites, Tripti 30.32 and 30.55 tonnes, and the local variety 25.8 and 25.1 tonnes.

Tripti became BARI SP-1 and Kamala Sundari BARI SP-2. They differ in colour and food value. The 2016 Foods study, which analysed nine BARI varieties grown at the Tuber Crops Research Centre in Gazipur, recorded Tripti's flesh as light orange and Kamala Sundari's as orange. Kamala Sundari held 6.38 milligrams of total carotenoids per 100 grams of fresh weight, against 0.55 milligrams in Tripti. The highest value, 7.24 milligrams, was found in BARI SP-8.

The study also gave the local names of the other early varieties: BARI SP-3 is Doulotpuri, BARI SP-6 is Lalkothi and BARI SP-7 is Kalmegh. BARI SP-4 and BARI SP-8 have orange flesh; SP-3, SP-5, SP-6, SP-7 and SP-9 have light orange flesh.

The DAE's BAMIS crop sheet lists BARI Mishti Alu-1 through BARI Mishti Alu-13 as notable improved varieties. By the time of the Heliyon study in 2023, BARI had developed 17 sweet potato varieties. In that study's trials in Gazipur, Bogura, Jamalpur, Jashore and Chattogram during 2021-22, the marketable yields were:

• BARI Mishti Alu-12: 39.88 tonnes per hectare, the highest
• BARI Mishti Alu-15: 36.60 tonnes per hectare
• BARI Mishti Alu-9: 33.78 tonnes per hectare
• BARI Mishti Alu-10: 28.56 tonnes per hectare
• BARI Mishti Alu-17: 25.98 tonnes per hectare

For planting material, growers can contact BARI's Tuber Crops Research Centre in Gazipur and its research sub-centres, and the DAE's nurseries and upazila offices, which can say where clean vines of a released variety are available nearby.

Sweet potato does not tolerate frost. It grows best at an average temperature of 24 degrees Celsius, with plenty of sunshine and warm nights. An annual rainfall of 750 to 1,000 millimetres is considered most suitable. The crop is sensitive to drought when its roots begin to form, about 50 to 60 days after planting, and it cannot stand waterlogging, which can rot the roots.

It grows on many soils, but well-drained, light and medium-textured soils with a pH of 4.5 to 7.0 suit it best. The DAE's crop sheet asks for land ploughed and laddered several times until the soil is loose and crumbly, so that the roots can swell freely.

In Bangladesh it is a rabi crop. The DAE gives the planting time as the Bengali months of Kartik and Agrahayan, from mid-October to mid-November, and says vines can be planted from Kartik to mid-Agrahayan, that is from mid-October to the end of November.

BARI scientists tested the timing at the Tuber Crops Research Sub-Centre in Bogura during the 2020-21 rabi season, planting BARI Mishti Alu-12 on 30 October, 10 November, 20 November and 30 November. Their study, published in the Bangladesh Journal of Agricultural Research, found that planting on 20 November with the highest fertiliser level gave the best result: 46.99 tonnes per hectare, a gross margin of 795,131 taka per hectare and a benefit-cost ratio of 4.62.

Sweet potato is grown from vine cuttings; true seed is used only for breeding. The original Agro News guide and the DAE's crop sheet agree on the main steps:

• Cut vines 25 to 30 centimetres long; the DAE gives each piece as 10 to 12 inches.
• Use top cuttings, which carry the growing tip and give the highest yield. Where top cuttings are available, do not plant middle pieces, and never use old, hard vines.
• If a middle piece must be used, make sure its lower end, the end nearer the root, goes into the soil.
• Plant in lines on flat land, keeping 24 inches (60 centimetres) between lines and 12 inches (30 centimetres) between vines.
• Lay each cutting so that two or three nodes are under the soil, and bend the upper part upright.
• The DAE puts the need at about 56,000 vines per hectare, depending on the variety.
• If the weather is dry at planting, trim a few leaves; if the soil lacks moisture, water the base of the cuttings.

The original Agro News guide warned that most Bangladeshi farmers apply too little fertiliser to sweet potato, and that balanced feeding is needed for a good yield. The DAE's BAMIS crop sheet gives these rates per hectare:

• Cow dung or other organic manure: 8 to 10 tonnes
• Urea: 160 to 180 kilograms
• TSP: 150 to 170 kilograms
• MOP (potash): 180 to 200 kilograms

The DAE's sheet also gives the same doses per decimal for small plots: 1 to 1.5 kilograms of cow dung, 650 to 700 grams of urea, 600 to 650 grams of TSP and 700 to 750 grams of MOP.

All the cow dung and TSP, with half the urea and half the potash, go into the soil at the last ploughing before planting. The remaining urea and potash are applied beside the rows 60 days after planting. Where the soil lacks sulphur or zinc, the original guide advised adding those nutrients; the upazila agriculture office can say whether a field needs them.

Research shows the effect of feeding. In the Bogura trial, marketable yield rose as the fertiliser dose increased, and the best treatment, as the abstract states it, was 100-95-120 kilograms of NPK per hectare. The Heliyon trials used 10 tonnes of cow dung per hectare with urea, TSP, MOP, gypsum, zinc sulphate, magnesium sulphate and boric acid. Fields and soils differ, so a soil test or the local agriculture officer's advice is the surest guide.

Sweet potato tolerates dry spells better than many crops, but it still needs water at the right time. The DAE advises two or three irrigations, depending on soil moisture, at 30, 60 and 90 days after the vines have taken root. Rain or irrigation water must not be allowed to stand in the field: it pushes leaf and vine growth but lowers the yield. Where heavy rain is likely, keep a way to drain the excess quickly.

When the soil comes into workable condition after watering, the DAE suggests breaking the surface crust with a spade or weeder. Weeds should be pulled within 25 to 30 days of planting and before each irrigation, and the field kept clean until the vines cover the ground.

In the Heliyon trials, BARI scientists earthed up the soil around the plants three times at monthly intervals, starting in the second month after planting.

The most serious pest is the sweet potato weevil, Cylas formicarius. A University of Florida extension profile, first published in 1998, calls it the most serious pest of sweet potato around the world, causing damage both in the field and in storage, with reported losses ranging from 5 to 97 percent.

The larvae tunnel through the roots, leaving them riddled with cavities, spongy and dark. Even light feeding makes the roots bitter and gives them a terpene smell. Yellowing vines are a sign, but usually only after heavy infestation, so the damage is often seen only at harvest. The adults lay eggs in the root or stem, and sometimes crawl down cracks in dry soil to reach the roots.

The University of Florida profile lists cultural measures that cut weevil numbers:

• Plant new fields away from the previous crop and from sweet potato stores, and rotate fields.
• Remove discarded and unharvested roots, which can carry large weevil populations.
• Control wild Ipomoea weeds, which are alternate hosts.
• Keep the soil moist, because cracked, dry soil favours the weevil.
• Use pheromone traps to monitor adult numbers.

The DAE also advises pheromone traps for the weevil and names a soil treatment with an approved pesticide, followed by light irrigation. Its crop sheet also covers leaf miners, tortoise beetles and flea beetles, and diseases such as stem rot, leaf spot and powdery mildew. Because these products and doses must suit the field and be used safely, ask the upazila agriculture officer or the sub-assistant agriculture officer before spraying, read the label, wear protective clothing, keep sprayed water out of open water bodies, and follow the waiting period before selling.

The DAE says sweet potato matures in 90 to 120 days. A ripe root releases a thick, milky sap when its skin is scratched. The roots should be lifted with a plough or spade, after the vines are cut, before the rains arrive; the original guide advised finishing the harvest by March. The BARI trials published in 2023 harvested at 130 days after planting, and the orange-fleshed varieties in the 2016 Foods study were harvested at maturity after about four to five months.

The DAE puts the yield at 160 to 170 kilograms per decimal, depending on the variety. The original guide advised separating the roots from the vine with a sharp knife rather than tearing them off, to keep them free of disease in storage.

For storage, the DAE recommends a sand bed in a store or on a raised platform: a 3.9-inch layer of sand, then a 29.5-inch layer of sweet potatoes, then another 3.9-inch layer of sand, repeated in several tiers. Stored this way, the roots are protected from the weevil.

Help is close at hand. The upazila agriculture office and the sub-assistant agriculture officer of each block can advise on varieties, fertiliser and pest control and on where to find clean vines. BARI's Tuber Crops Research Centre in Gazipur and its sub-centres, such as the one in Bogura, work on sweet potato varieties and their management.

Photo: Vmenkov / Wikimedia Commons (CC BY-SA 3.0)

Sources: The Agro News (Staff Correspondent), Department of Agricultural Extension (BAMIS crop sheet, Sweet potato cultivation at a glance), Alam and others, BARI Tuber Crops Research Centre (Heliyon, July 2023), Mondol and others, BARI (Bangladesh Journal of Agricultural Research, vol. 47 no. 3, published November 2023), Alam, Rana and Islam, University of Dhaka (Foods, September 2016), A.F.M. Fazlur Rahman (Proceedings of the 13th Bangladesh Science Conference, 1988), University of Florida IFAS (Sweetpotato Weevil, Featured Creatures), International Potato Center (Annual Report 2021), The Daily Star Bangla (27 January 2024), The Daily Ittefaq (26 April 2021), The Financial Express (9 November 2020), Wikipedia (Sweet potato, March 2025)