Maize: nutrition, cultivation and a profitable crop for Bangladesh

Drive through Dinajpur, Thakurgaon or Lalmonirhat at the end of winter and the road runs between rows of green plants as tall as a person, crowned with golden tassels. A few decades ago maize was an unfamiliar crop in Bangladesh's fields. Today it is one of the country's most important cereals after rice. Maize is among the world's great food grains, and its weight in Bangladeshi farming grows every year. It is rich in nutrition and profitable too, with wide use as food, as animal feed and in industry.

The grain is eaten by people, and the stalks and green leaves make good cattle fodder. Maize is also central to poultry and fish feed. An older estimate put the grain needed each year for livestock, poultry farms and fish alone at about 270,000 tonnes. That figure has long been overtaken, as poultry and fish farming have grown many times over, and maize acreage with them.

A report in The Financial Express, citing figures from the Bangladesh Bureau of Statistics (BBS) and the Department of Agricultural Extension (DAE), gives a recent picture. It said a record 4.55 million tonnes of maize were produced from about half a million hectares in fiscal 2023, and that output had grown roughly fivefold in 15 years. Between 50 and 60 per cent of local maize goes to feed mills. Even so, to meet total national demand of 6 to 6.5 million tonnes a year, Bangladesh has been importing 2 to 2.4 million tonnes annually for the past five years. The market, in short, wants more maize than the country grows.

The same report traces commercial maize growing in Bangladesh back to the 1990s. As the poultry industry grew, so did demand from feed mills, and farmers began choosing maize as a profitable winter crop. Growing began in the north, in districts such as Dinajpur, Thakurgaon, Rangpur and Lalmonirhat, and over the past five years has spread to the northwest, the southwest and the central districts.

Research has driven much of that spread. Alongside BARI, the Bangladesh Wheat and Maize Research Institute now works on the two crops, on new varieties, tolerance of drought and heat, and disease resistance, some of whose results appear in the variety guide below. For farmers the draw is mainly profit: the same Financial Express report put farmers' margin on maize at no less than 60 per cent. That return, together with steady demand from feed mills, has made maize a crop northern farmers rely on. Rotating maize with rice on the same land also adds variety to the cropping, which helps both soil health and the control of pests and disease.

Maize is more nutritious than rice or wheat. It contains about 11 per cent protein, and that protein is relatively rich in essential amino acids, notably tryptophan and lysine. Amino acids are the building blocks of protein; the essential ones cannot be made by the body and must come from food. Yellow maize is reported to contain about 90 milligrams of carotene, the source of vitamin A, per 100 grams of grain. The yellow or orange colour of the kernel is the sign of that carotene.

Maize meets many of the body's needs. It provides:

• Protein: for building and repairing the body.
• Carbohydrate: the main source of energy.
• Vitamins: A, B and E.
• Minerals: magnesium, phosphorus and iron.
• Fibre: which aids digestion and eases constipation.

Several benefits are attributed to maize because of these nutrients. Its carbohydrate supplies quick energy. Its fibre is considered good for the heart because it helps control blood cholesterol. Its vitamin A is good for the eyes. Its glycaemic index, a measure of how quickly a food raises blood sugar, is considered relatively low, so it is described as helpful for blood sugar control. Its antioxidants are thought to help keep skin young. Anyone with diabetes or heart disease should still consult a doctor or nutritionist before changing their diet.

Sandy loam and loam suit maize best. The field must not hold standing water, since maize roots cannot tolerate waterlogging. A soil pH of 5.8 to 7.0, slightly acidic to neutral, is ideal. Maize needs warm, sunny weather and grows best at 20 to 30 degrees Celsius.

Choose seed of high-yielding, disease-resistant varieties, at 20 to 25 kilos per hectare. In Bangladesh maize can be sown in two seasons. In the rabi season the right time runs from mid-Ashwin to mid-Agrahayan, or October to November; in the kharif season from Falgun to mid-Chaitra, or mid-February to March. Most of the country's maize is grown in rabi.

Maize is sown in rows 60 centimetres apart, with 20 to 25 centimetres between plants in the row. Rows give every plant an equal share of light and air, and make weeding, fertilising and irrigation much less laborious.

Through collecting and selecting maize lines, the Bangladesh Agricultural Research Institute (BARI) has bred a series of improved varieties. Many use parent lines from the International Maize and Wheat Improvement Center, known as CIMMYT, based in Mexico. A hybrid is a variety made by crossing two distinct parent lines, and it usually yields more. With demand rising, these versatile varieties have a bright future. Two terms describe the grain: flint means a hard, smooth, glossy kernel; dent means a kernel whose top forms a dimple as it dries.

BARI Hybrid Maize-5, a protein-rich high-yielder, was approved in 2004. It takes 140 to 145 days in rabi and 95 to 105 days in kharif. The grain is bright orange and flint, with a thousand kernels weighing 290 to 310 grams. It yields 9 to 10 tonnes a hectare in rabi and 7 to 7.5 tonnes in kharif.

BARI Hybrid Maize-7, a single cross of selected CIMMYT parent lines, was released in 2006. It takes 135 to 141 days in rabi and 95 to 100 in kharif. The grain is yellow and flint, a thousand kernels weighing 370 to 390 grams. It yields 10.5 to 11.5 tonnes a hectare in rabi.

BARI Hybrid Maize-9, also from CIMMYT lines, was released in 2007. It takes 145 to 150 days in rabi and 105 to 110 in kharif. The grain is yellow and dent, a thousand kernels weighing 370 to 375 grams, and it yields 11.5 to 12.5 tonnes a hectare in rabi.

BARI Hybrid Maize-10, a cross of CIMMYT lines with BARI's own inbred lines, was released in 2009. It takes 145 to 150 days in rabi and 100 to 110 in kharif, has yellow flint grain and yields 10 to 11.5 tonnes a hectare in rabi. BARI Hybrid Maize-11, released the same year from CIMMYT lines, takes 150 to 155 days in rabi, has yellow flint grain and yields 10.5 to 11.5 tonnes a hectare.

BARI Hybrid Maize-12 and 13 were released in 2016. Both have white flint grain, give good yields with little irrigation and tolerate moderate drought. Maize-12 takes 140 to 145 days in rabi; under drought, with a single irrigation before flowering, it yields 8.1 to 8.5 tonnes a hectare, and with normal irrigation 10 to 11.1 tonnes. Maize-13 takes 145 to 152 days; with one irrigation it yields 8.2 to 8.9 tonnes, and with normal irrigation 10.1 to 11.2 tonnes. Its stalks and leaves stay green after the cobs mature, making good fodder.

BARI Hybrid Maize-14 and 15 were released in 2017. Both tolerate high heat at flowering in the kharif season and resist leaf blight. Maize-14 is a moderate yielder with white, semi-dent grain; it takes 140 days in rabi and 115 in kharif, with average yields of 10.84 tonnes a hectare in rabi and 10.52 in kharif. Maize-15 is a high yielder with yellow, semi-dent grain; it takes 148 days in rabi and 121 in kharif, averaging 12.75 tonnes in rabi and 12.07 in kharif. Most of its leaves stay green at maturity, so it too doubles as fodder.

For eating fresh there is BARI Sweet Corn-1, selected from germplasm, or breeding material, brought from Thailand and approved in 2002. Sweet corn is eaten young, so the cobs are picked while the kernels are soft: within 20 to 25 days of silking, when the silky threads emerge from the tip of the cob, which is 115 to 120 days after sowing. The yellow kernels are rich in vitamin A. In rabi it yields 10 to 10.5 tonnes a hectare of husked young cobs, plus about 25 tonnes of green fodder.

Maize is a hungry crop, and without proper feeding even a high-yielding variety will disappoint. It needs both organic and chemical fertiliser. How much of each depends on the soil, so the best guide is a soil test, or the Fertilizer Recommendation Guide of the Bangladesh Agricultural Research Council (BARC) together with advice from the upazila agriculture office.

The method of application is fixed. At the final ploughing, spread one third of the recommended urea and all of the other fertilisers, and plough them in. The remaining urea is top-dressed in two equal splits: the first 25 to 30 days after emergence, the second 40 to 50 days after. Within 30 days of emergence, thin out extra seedlings so each spot has one strong plant, and keep the field weed-free until the seedlings are a month old.

In the rabi season, irrigation is essential for high-yielding maize to deliver, because there is almost no rain. The improved varieties can take three or four irrigations, timed to the plant's growth:

• First: within 15 to 20 days of sowing, at the 4 to 6 leaf stage.
• Second: within 30 to 35 days, at the 8 to 12 leaf stage.
• Third: within 60 to 70 days, as the cobs emerge.
• Fourth: within 85 to 95 days, before the grain fills.

Water matters most at flowering and grain filling, since a shortage then leaves cobs with fewer kernels. Yet at exactly this time the field must never be waterlogged. Weeds should be removed with a hand weeder as they appear.

At the seedling stage, cutworms come out at night and cut plants off at the base. When they strike, dig around the cut seedlings in the morning, find the caterpillars and kill them by hand. Stem borers weaken the plant; spray an approved insecticide where needed.

Seed rot and seedling death often thin the stand. Seed-borne and soil-borne fungi such as Pythium, Rhizoctonia, Fusarium and Penicillium cause seed rot, seedling blight and root rot. When the soil is wet and cold, seedlings take a long time to establish, and fungal attack rises in that window. The remedies:

• Use healthy, vigorous, undamaged seed, and the seed-rot-resistant varieties Barnali and Mohor.
• Prepare the land well and sow in moderate moisture at soil temperatures above 13 degrees Celsius.
• Treat the seed with thiram or Vitavax at 2.5 to 3 grams per kilo of seed.

Two fungi, Helminthosporium turcicum and Helminthosporium maydis, cause this disease; in Bangladesh the first is more common. Long grey lesions appear on the lower leaves and then spread upwards. In a severe attack the leaves dry early and the plant dies. The fungus survives for a long time in infected tissue, and its spores, called conidia, travel far on the wind to healthy plants. High humidity and temperatures of 18 to 27 degrees Celsius favour it. Control means growing the resistant variety Mohor, spraying Tilt 250 EC at 0.04 per cent two or three times at 15-day intervals, and after harvest removing or burning the infected plants.

Cob and grain rot reduces yield, seed quality and food value all at once. Fungi such as Diplodia maydis and Fusarium moniliforme are responsible. Infected husks and kernels discolour; the grain fails to fill and shrivels or cracks, and fungus is often visible between the kernels. Heavy rain between cob formation and ripening spreads it, as does lodging caused by insects, birds or stalk rot. The fungus survives in seed and crop debris and spreads fast where maize follows maize. The answer is not to grow maize on the same land year after year, to protect the crop from insects and birds, to harvest promptly when ripe, and to burn the crop remains after harvest.

Stalk rot is caused by the same kinds of fungi. The first sign is a rotting stalk, and the plant snaps and falls. In Bangladesh it is more common in kharif, and worse where soil nitrogen is high and potash low. The remedies:

• Treat seed with Vitavax-200 before sowing.
• Fertilise in balance, with nitrogen and potash at moderate rates.
• Burn the crop remains after harvest.
• Control the insects that attack roots and stalks.
• Spray an approved fungicide two or three times on affected fields.

Maize for grain is ready when the husk turns a glossy straw colour and the leaves begin to yellow. At this point a kernel pulled from the cob shows a black spot at its base, the sign that the grain is fully mature. Harvest when the cobs are 75 to 80 per cent mature. For seed, pick the large, well-filled kernels from the middle of the cob. Seed saved from a hybrid crop will not give the same quality next season, though, so with hybrids fresh seed is bought every season. After harvest, dry the grain thoroughly before storing it, since damp grain soon grows mould.

Demand for maize runs all year, as food, feed and an industrial raw material. Grown properly it yields 7 to 10 tonnes a hectare, and more in rabi with the better BARI varieties, as the variety guide above shows.

With the country importing more than 2 million tonnes a year, every extra tonne grown at home trims that bill and puts more money in farmers' hands. The steady appetite of poultry and fish feed mills also makes a sale more certain than for many crops. Farmers in the north have made maize their own over the past few decades. With the right variety, timely sowing, balanced fertiliser and a close watch on disease, farmers in other regions can draw the same income from this nourishing and profitable crop.

Photo: A maize field at Chandipur, Sundarganj, Gaibandha, Khairuzzaman / Wikimedia Commons (CC BY-SA 3.0)