Khagrachhari's Hill-Grown Mukhi Kachu Finds Buyers Across Bangladesh

Mukhi kachu, the taro grown for the clusters of small tubers around its parent corm, was spreading across the hill slopes of Khagrachhari district in the Chittagong Hill Tracts, Jagonews24's district correspondent reported on 20 November 2019. Farmers in the district were growing more of it to keep pace with demand for vegetables, and wholesalers said the crop, once sold mainly in the hills, had found a place in big wholesale markets in Noakhali, Cumilla, Chattogram and Dhaka.

Mukhi kachu is grown to some extent in many parts of Bangladesh, and the report said its cultivation had grown in Khagrachhari over the previous few years, as it had in the rest of the country. The crop goes by several local names, among them gura kachu, kachu, chhara kachu, duli kachu and binni kachu. Farmers keep the chhara, the cluster of small side tubers, as seed for the next season, and they lift the crop once the plants turn yellow and dry.

According to the report, mukhi kachu was grown in every upazila of Khagrachhari, but most of all in Matiranga, Guimara, Manikchhari and Ramgarh. The correspondent found the crop planted on the slopes of hills large and small; as far as the eye could see, the rolling hills were green with taro plants.

Local people told the paper that farmers were growing mukhi kachu on the slopes alongside rice and other vegetables, and that the crop had brought financial security to farming families. Md Shishu Mia and Md Shafiqul Islam, farmers from remote Tabalchhari in Matiranga, said mukhi kachu had changed the area's economy over the previous few years, and that the area under the crop was growing because it was profitable.

Md Abdul Kuddus, a taro grower from the Nakapa area of Ramgarh, said local farmers were making a profit because production costs were low.

The growers described a calendar set by the weather. At the start of the Bengali month of Chaitra (March-April), they clear the weeds and dig the soil to make it ready. When the rain comes in mid-April, they plant the seed cormels. After the shoots come up they weed again, earth the plants up into lines, known locally as kel, and apply fertiliser a few times as needed. Lifting and selling begin in early September.

That pattern matches what the Food and Agriculture Organization of the United Nations (FAO) describes for rain-fed, or dryland, taro in its 1999 guide Taro Cultivation in Asia and the Pacific, written by Professor Inno Onwueme for the FAO regional office in Bangkok. Because dryland taro depends on rainfall, the guide says, the time of planting is critical: it is usually done at the onset of the rainy season, and the rains must last long enough, six to nine months, for the crop to mature. Planting means opening the soil with a spade or digging stick, inserting the planting pieces and closing up. Manure and compost may be applied after planting or worked into the soil during land preparation, and where the soil is not deep and friable, ridges are made, usually 70 to 100 cm apart.

For dryland taro, the guide says, weeding is needed mainly in the first three months or so, until the crop closes its canopy. It advises keeping hand tools at the surface because taro roots are very shallow and easily damaged by deep weeding, and it recommends earthing up soil around the base of the plants during weeding so that the developing corms are protected, the same step the Khagrachhari growers described as making kel.

The farmers' harvest signal also matches the guide. For dryland taro, it says, maturity is signalled by a decline in the height of the plants and a general yellowing of the leaves, and the time from planting to harvest ranges from five to twelve months, depending on the cultivar and the season. Harvesting is mostly done by hand: the soil around the corm is loosened and the plant is pulled up by grabbing the base of its leaf stalks.

Research in Bangladesh describes the same window. In field trials at the Bangladesh Agricultural Research Institute (BARI) in Joydebpur and at its regional agricultural research stations in Jamalpur and Ishurdi during the kharif seasons of 2012 and 2013, published in the Bangladesh Journal of Agricultural Research in December 2016, seed cormels were planted between 11 and 30 March and the crops were harvested between 30 August and 12 December. The paper describes mukhi kachu as a kharif, or summer-season, crop generally grown from February or March to September or October.

Wholesalers Md Shahjahan and Md Nurul Alam told the paper that after meeting demand in the hills, mukhi kachu had found a place in big wholesale markets including Noakhali, Cumilla, Chattogram and Dhaka. There were depots (arat) for the crop at Hatimura and Gachchhabil in Manikchhari, at Nakapa in Ramgarh, and at Tabalchhari and Taindong in Matiranga. Because prices at these depots were relatively low, the traders said, they were making a profit.

Several of these places appear in Banglapedia, the national encyclopedia of Bangladesh published by the Asiatic Society of Bangladesh. It lists Tubalchhari Hat and Taindang Hat among the notable markets of Matiranga upazila, Nakaba Bazar among those of Ramgarh and Gachhabil Bazar among those of Manikchhari. Tubalchhari and Taindang are also two of the unions of Matiranga upazila.

Moving taro over long distances is not simple. The FAO guide calls the taro corm an awkward market commodity: it is bulky, consisting of about two-thirds water, it is fragile and easily bruised, and it keeps for only a few days at ambient temperatures. Because most taro is sold fresh, with few processed forms, the guide says the success of taro as a cash crop depends on an adequate marketing structure.

The timing of the harvest works in the growers' favour. The BARI paper notes that mukhi kachu is considered an important vegetable particularly in August to October, when the supply of other vegetables in the market is scarce, citing earlier Bangladeshi studies. The Khagrachhari harvest, which the growers said begins in early September, falls inside that period.

Sub-assistant agriculture officer Md Amir Hossain told the paper: "Farmers are turning to taro because the profit per hectare is double the cost of production."

Matiranga upazila agriculture extension officer Md Masum Bhuiyan said: "There is hardly any chance of financial loss in growing mukhi kachu."

The BARI trials give an independent picture of the economics on research farms. Valuing the produce at Tk 15 a kilogram, the scientists recorded the highest benefit-cost ratios, as two-year averages, of 2.93 at Joydebpur and 3.42 at Ishurdi with the recommended fertiliser dose and plants spaced 60 cm by 30 cm, and of 3.12 at Jamalpur with a dose 25 per cent above the recommendation at the same spacing. At Joydebpur, the cost of cultivation across the treatments ran from Tk 89,780 to Tk 104,940 per hectare, and the highest gross return there was Tk 300,600 per hectare.

Those figures come from research stations in the plains, from one variety, Bilashi, and from two seasons; they are not measurements from Khagrachhari's hill farms. They do show that, on research farms, the crop's gross return was well above its cost of cultivation.

Mukhi kachu belongs to the aroids, which Banglapedia describes as herbaceous plants of the family Araceae and one of the oldest domesticated groups of plants, growing in moist and shady places and originating in the tropics of the Old World. Their enlarged underground stem acts as a storage organ and is the part mostly eaten. Among the aroids in Bangladesh, Banglapedia says, mukhi kachu and pani kachu are the most important and are grown commercially in all parts of the country, while dudh kachu and moulavi kachu are cultivated in some areas for their stems and leaves, and the leaves of wild Colocasia plants are also eaten.

The FAO guide classifies cultivated taro as Colocasia esculenta and describes two botanical varieties. The dasheen type has a large cylindrical central corm and very few cormels; the eddoe type has a small globular central corm with several relatively large cormels arising from it. The guide says taro is postulated to have originated in southern or south-east Asia. A 2014 study by researchers at Rajshahi University, published in the Bangladesh Journal of Botany, describes taro, locally called mukhikachu, as an ancient crop in Bangladesh that grows on hilly areas as well as on the plains, and records that the team collected 457 edible taro accessions from 13 aroid-growing districts of the country in 2005 and 2006.

The growth cycle explains why farmers keep the side tubers as seed. According to the FAO guide, corm formation begins about three months after planting, and in cultivars that produce many cormels, cormel formation follows soon afterwards. By about the sixth month, when shoot growth declines, the corm and cormels become the main store of the plant and grow very rapidly. As the dry season sets in, the shoot dies back, and the corm and cormels allow the plant to survive; if they are not harvested, they sprout and give rise to new plants at the start of the next favourable season.

In the BARI trials, the scientists counted secondary corms and cormels as the edible yield of mukhi kachu, which is the part that reaches the market as the small, round tubers sold in Bangladeshi bazaars.

Banglapedia records that one variety of mukhi kachu, Bilashi, yields 30 to 35 tonnes per hectare, against an average of about 8 tonnes per hectare for aroids. The BARI paper puts the national yield of mukhi kachu at 9.76 tonnes per hectare, citing the Bangladesh Bureau of Statistics (BBS) for 2011, and calls it low compared with China at 17.05 and Japan at 11.59 tonnes per hectare, citing FAO figures from 1999. It also notes that the area and gross annual production of mukhi kachu in Bangladesh had been increasing year after year. The FAO guide gives average taro yields of about 12.6 tonnes per hectare in Asia and 6.2 tonnes per hectare in Oceania.

The authors suggested that spacing that is too wide or too close and unbalanced fertiliser use could be two important reasons for the low national yield. In their trials, with the variety Bilashi, the closest spacing tested, 60 cm by 30 cm, combined with fertiliser 25 per cent above the recommended dose, gave the highest edible yield at all three sites as a two-year average: 20.04 tonnes per hectare at Joydebpur, 20.75 at Jamalpur and 16.63 at Ishurdi. The widest spacing, 60 cm by 60 cm, with 25 per cent less fertiliser, gave the lowest.

The recommended dose used in the trial came from the national Fertilizer Recommendation Guide of 2005: per hectare, 3,000 kg of cow dung and nutrients equal to 96 kg of nitrogen, 27 kg of phosphorus, 81 kg of potassium and 18 kg of sulphur. All the phosphorus, potassium and sulphur were applied at planting, and the nitrogen was given in two parts, 15 to 20 days and 40 to 45 days after planting. The authors concluded that farmers around Joydebpur and Ishurdi might use the recommended dose with 60 cm by 30 cm spacing, and farmers around Jamalpur a dose 25 per cent higher at the same spacing.

They explain that mukhi kachu needs a high dose of nitrogen and potassium: nitrogen for growth, and potassium for starch and tuber formation. The FAO guide adds that in high-rainfall areas fertiliser, compost or manure is best applied in split doses, the first at planting and the second three to four months later when the corms are enlarging, to limit leaching. The BARI paper also notes that the fertiliser a crop needs varies with the cultivar, plant population and soil type of each agro-ecological zone, so hill growers are best advised to set their doses with the upazila agriculture office.

Disease is the other risk the FAO guide stresses. It names taro leaf blight, caused by Phytophthora colocasiae, as one of the most damaging diseases of taro in the Asia-Pacific region: it starts as purple-brown, water-soaked spots on the leaf and can destroy the whole leaf blade in 10 to 20 days, and high temperature and humidity favour its spread. The guide lists careful choice of planting material, intercropping, crop rotation and removal of infected leaves among the farm practices that have given partial control. Farmers who see such symptoms should seek advice from their upazila agriculture officer.

Khagrachhari is one of the three districts, with Rangamati and Bandarban, into which the Chittagong Hill Tracts were divided in the early 1980s. Banglapedia describes the Hill Tracts as the only extensive hill area of Bangladesh, covering about 13,184 square kilometres, roughly one-tenth of the country. Mean annual rainfall is nearly 2,540 mm in the north and east of the region; the dry, cool season runs from November to March, the hot pre-monsoon season from April to May, and the warm, wet monsoon from June to October. The hill soils are mainly yellowish-brown to reddish-brown loams and are very strongly acidic.

These conditions suit taro in several ways. The FAO guide says the crop needs a high supply of moisture, normally 1,500 to 2,000 mm of rain or irrigation for good yields, an average daily temperature above 21 degrees Celsius, and does best in soil of pH 5.5 to 6.5. It also says taro is more shade-tolerant than most crops, which lets it fit into intercropping systems with tree crops and other crops.

The growers' calendar follows the same rains as the older hill farming system. Banglapedia describes jhum, or shifting cultivation, as the most prevalent form of cultivation in the hill areas of Bangladesh, practised on slopes outside the reserve forests. In jhum, seeds are sown after the first rain in April, and crops such as rice, maize, millet, sesame, cucumber, pumpkin, cotton, banana, ginger and turmeric are harvested in succession from July to December. Banglapedia also records the concern about the system: it states that about 20,000 hectares are brought under jhum every year, with a loss of 100 to 250 tonnes of soil per hectare, and that the fallow period has shrunk from the traditional ten years to two or three.

Banglapedia gives Khagrachhari district an area of 2,505.73 square kilometres. It borders the Indian state of Tripura to the north, Rangamati and Chattogram districts to the south, Rangamati to the east, and Chattogram district and Tripura to the west; its main rivers are the Maini and the Chengi. The 2011 census counted 569,715 people, and Banglapedia names the Chakma, Marma, Tripura and Tanchangya among the indigenous communities of the district. Khagrachhari was a sub-division of the Hill Tracts until it became a district in 1983. Agriculture was the main source of income for 59.92 per cent of households.

Matiranga, on the Tripura border, is where the farmers quoted in the report live. Banglapedia lists its main crops as paddy, rubber, sugarcane, potato, corn, cotton, arahar and vegetables, and gives agriculture as the main source of income for 60.50 per cent of its households. In the 2011 census, Guimara, now named in the report as one of the leading taro upazilas, was listed as a union of Matiranga.

Ramgarh, south of Matiranga, has been an administrative centre since its thana was formed in 1905; Banglapedia records that the force now known as Border Guard Bangladesh was first formed there as the Ramgarh Local Battalion in 1795. Its main crops are paddy, sweet potato, ginger, turmeric, sugarcane, bamboo and vegetables, and the upazila is home to a Soil Conservation and Research Centre and the Ramgarh Horticulture Centre. Manikchhari, further south on the border with Fatikchhari, relies on agriculture for 67.32 per cent of households; its main crops include paddy, corn, potato, ginger, turmeric and vegetables, and it sends bananas, jackfruit, ginger, turmeric and vegetables out of the area.

The FAO guide says the fresh taro corm is about two-thirds water, with 13 to 29 per cent carbohydrate, mostly starch, and 1.4 to 3.0 per cent protein. The leaves are richer in protein and also contain calcium, phosphorus, iron, vitamin C and B vitamins. Banglapedia notes that the corms of mukhi kachu are rich in starch and can be eaten much like potatoes: boiled, baked, roasted or fried, and that a flour similar to potato flour can be made from them.

Raw taro is not eaten. According to the FAO guide, contact of the raw corm with the mouth or skin causes considerable itchiness, acridity and discomfort, and even raw leaves and leaf stalks can do so. The effect is attributed to bundles of calcium oxalate crystals, called raphides, in the plant's tissue. Its strength varies between cultivars, and growers and consumers prefer those with low acridity; stress such as drought or poor nutrition during the season can make it worse. The guide says the acridity disappears when the corm or leaf is cooked by boiling, roasting, frying or other means, which is why mukhi kachu is always cooked before it is eaten.

Photo: Iqbalctgbd / Wikimedia Commons (CC BY-SA 4.0)

Sources: Jagonews24 (20 November 2019), Food and Agriculture Organization of the United Nations (Taro Cultivation in Asia and the Pacific, 1999), Bangladesh Journal of Agricultural Research (BARI study, December 2016), Bangladesh Journal of Botany (2014), Banglapedia (Asiatic Society of Bangladesh)