Black Gram Farming: Optimal Growth Conditions and Management

Black gram (Vigna mungo), commonly known as urad or urd bean, is one of the most important pulse crops in India. It is a staple in Indian kitchens – the key ingredient behind dal makhani, crispy vadas, idli, dosa, and papads. Beyond its culinary value, black gram is a powerhouse of nutrition, packing roughly 25% protein along with significant amounts of calcium, iron, and folate. India is the world’s largest producer of this crop, and understanding its growth requirements and management practices is essential for anyone involved in pulse cultivation.

Origin and importance of black gram 🔗

Black gram originated in South Asia and has been cultivated on the Indian subcontinent for thousands of years. It is believed to have been domesticated in India roughly 4,500 years ago from its wild ancestor, Vigna mungo var. silvestris. Today, India remains the dominant producer, with the crop covering approximately 4.67 million hectares and yielding a total production of around 2.45 million tonnes. Other significant producers include Myanmar, Pakistan, Bangladesh, and Thailand.

The crop holds a multi-dimensional role in Indian agriculture. As a legume, it fixes atmospheric nitrogen through its symbiotic relationship with Rhizobium bacteria, thereby improving soil fertility for the crops that follow. Its deep root system helps prevent soil erosion and compete with weeds. Black gram also serves as a nutritive fodder for milch cattle, and when ploughed back into the field, it functions as a green manure crop. For smallholder farmers, it fits well into intensive crop rotations due to its short duration of 65-100 days.

Climate requirements 🔗

Black gram is essentially a tropical and subtropical crop that thrives in warm and humid conditions. The ideal temperature range for its growth is 25-35°C, although the plant can tolerate a broader range of 8-40°C depending on the altitude and season. It grows successfully from sea level up to an elevation of about 1,800 metres.

Rainfall and moisture 🔗

The crop performs best with an annual rainfall of 600-1,000 mm. However, excessive rain – especially during flowering – can severely reduce seed yields. In high-rainfall regions, black gram is best grown during the dry season on residual soil moisture. Being moderately drought-tolerant once established, it is well suited for semi-arid and dryland farming systems.

Seasons of cultivation 🔗

Black gram is predominantly a kharif (monsoon) crop, sown in June-July and harvested in October-November. However, it is also cultivated during the rabi season in central and southern India where winter temperatures remain moderate, and as a summer crop (February-April) in north India and rice fallows. Rabi and summer sowings often deliver higher productivity because of fewer pest pressures, provided irrigation is available.

Soil requirements 🔗

Black gram adapts to a wide range of soils, but it performs best in well-drained loamy or heavy black cotton soils that retain moisture effectively. The preferred soil pH is in the range of 5.5-6.5, though the crop can tolerate values from 4.5 to 7.5 when appropriate soil amendments are made.

Saline, alkaline, and waterlogged soils should be strictly avoided, as black gram is quite sensitive to these conditions. Good internal drainage is essential – waterlogging at any growth stage can lead to root rot and poor nodulation. Before sowing, the field should receive 2-3 deep ploughings followed by harrowing and levelling, with 5-10 tonnes of farmyard manure incorporated during the final ploughing to improve soil structure and organic matter content.

Improved varieties 🔗

Choosing the right variety is one of the simplest ways to boost yield and manage diseases. India’s agricultural research system has released several high-yielding and disease-resistant varieties. Some notable ones include:

Pant U-31 (PU-31) – a widely recommended variety known for good yield and adaptability. T-9 – one of the earliest released varieties, moderately tolerant to drought. IPU 94-1 (Uttara) and Shekhar 3 (KU 309) – resistant or tolerant to yellow mosaic virus. LBG-884 and TAU-2 – suited for heavier soils and partially shaded conditions. VBN (Bg) 7 and Pusa-1 – recommended for regions with high yellow mosaic pressure. Farmers should select varieties based on their specific region, season, soil type, and prevalent disease scenario.

Seed rate, spacing, and sowing 🔗

The seed rate varies by season and method of sowing. For kharif sowing, a seed rate of 12-15 kg per hectare with a spacing of 30 × 10 cm is standard. For summer sowing, the rate increases to 20-25 kg per hectare with narrower row spacing of 20-25 × 10 cm, as the crop tends to be less vigorous in the hot season.

Seed treatment 🔗

Proper seed treatment is critical for healthy germination and early disease protection. Seeds should first be treated with a fungicide such as Thiram or Carbendazim at 2.5 g per kg of seed to guard against seed-borne diseases like seedling rot and anthracnose. After the chemical treatment, seeds should be inoculated with Rhizobium culture at 20-25 g per kg of seed. This inoculation enhances nitrogen fixation, reducing the crop’s dependence on synthetic nitrogen fertilisers. Some recommendations also include treating seeds with Imidacloprid 70 WS at 7 g/kg to protect against early sucking pests, particularly whiteflies that transmit yellow mosaic virus.

Time of sowing 🔗

For kharif, the ideal window is the second fortnight of June (15-30 June) in most parts of India. For summer cultivation, sowing should be completed between mid-February and early April. Delayed sowing reduces yields significantly – studies have recorded up to 80% yield decline when sowing is delayed by three weeks from the onset of monsoon.

Nutrient management 🔗

Although black gram fixes its own nitrogen, it still benefits from a starter dose of fertiliser. The commonly recommended fertiliser dose is 20 kg nitrogen, 40 kg phosphorus (P₂O₅), and 40 kg potassium (K₂O) per hectare, all applied as a basal dose at the time of sowing.

For rainfed conditions, a reduced dose of 12.5 kg N + 25 kg P₂O₅ + 12.5 kg K₂O per hectare is usually adequate. Under irrigated conditions, the dose can be raised to 25 kg N + 50 kg P₂O₅ + 25 kg K₂O per hectare along with 20 kg sulphur. Applying sulphur (through gypsum or single super phosphate) and zinc sulphate at 25 kg/ha has been shown to further improve yields. A foliar spray of 2% DAP at the flowering stage can help enhance pod setting and grain filling.

Irrigation management 🔗

Kharif black gram generally does not require supplemental irrigation if monsoon rains are well-distributed. However, if dry spells occur during critical stages, one or two irrigations become essential. In summer cultivation, the crop requires irrigation at intervals of 10-15 days, depending on soil type and weather.

The two most critical stages for moisture are flowering and pod formation. Water stress during these periods directly reduces the number of pods per plant, seeds per pod, and overall grain weight. At the same time, waterlogging must be avoided at all stages, as it promotes root diseases and hampers nitrogen fixation. Drip irrigation, where feasible, offers an efficient way to deliver water directly to the root zone while conserving resources.

Weed management 🔗

Weeds compete heavily with black gram during its first 30-40 days of growth. If left unchecked, they can reduce yields by 40-60%. One or two hand weedings within the first 40 days after sowing are effective for managing weeds in smaller fields.

For chemical weed control, a pre-emergence application of Pendimethalin at 1.0 kg active ingredient per hectare within 2-3 days of sowing provides good broad-spectrum control. This can be followed by a post-emergence spray of Imazethapyr at 50 g active ingredient per hectare around 15-20 days after sowing if weed pressure persists. Combining a pre-emergence herbicide with one hand weeding has consistently proven superior in research trials across Indian dryland conditions.

Major diseases and their management 🔗

Yellow mosaic disease (YMD) 🔗

Yellow mosaic is the single most devastating disease of black gram. Caused by the Mungbean Yellow Mosaic India Virus (MYMIV), it is transmitted by the whitefly Bemisia tabaci. Infected plants show scattered yellow patches on leaves, stunted growth, and produce fewer and smaller pods. Yield losses can range from 30% to 100% under favourable conditions for the vector.

Management involves an integrated approach: growing resistant varieties (such as IPU 94-1, Pusa-1, or VBN(Bg) 7), treating seeds with systemic insecticides like Thiamethoxam or Imidacloprid to control early whitefly populations, and applying foliar sprays of Acetamiprid or Dimethoate when whitefly numbers build up. Planting border crops such as sorghum or maize around the field and using yellow sticky traps can help reduce whitefly entry. Timely sowing to avoid peak whitefly season also helps.

Powdery mildew 🔗

Powdery mildew appears as white, powdery patches on leaves, stems, and pods, eventually turning dirty white and causing premature maturity. It is more severe in humid conditions and late-sown crops. Spraying wettable sulphur at 3 kg/ha or Carbendazim at 0.1% at the first sign of symptoms provides effective control.

Cercospora leaf spot and anthracnose 🔗

Cercospora leaf spot produces brown, circular spots on leaves, while anthracnose causes dark, sunken lesions on pods and stems. Both diseases can be managed by spraying Mancozeb (0.25%) or Carbendazim (0.1%) twice at 15-day intervals. Using disease-free certified seed and treating seeds with fungicides before sowing serve as the first line of defence.

Major insect pests and their control 🔗

Whitefly 🔗

Apart from transmitting yellow mosaic virus, whiteflies directly damage plants by sucking sap. Seed treatment with Imidacloprid, combined with foliar sprays when populations exceed the economic threshold, is the standard approach.

Pod borers 🔗

Spotted pod borer (Maruca vitrata) and gram pod borer (Helicoverpa armigera) feed on flowers, buds, and developing pods, causing direct yield loss. Control measures include spraying Quinalphos or Acephate and releasing Trichogramma parasitoids at 65,000 per hectare for biological control. Neem-based products (NSKE at 5%) can be used during later growth stages to keep residues minimal.

Aphids and jassids 🔗

These sucking pests weaken plants by extracting sap, causing yellowing, curling, and distortion of leaves. Spraying Dimethoate at 2 ml/litre or Acephate at 1 g/litre effectively controls both pests. Monitoring pest populations regularly and spraying only when necessary helps preserve natural enemies.

Harvesting and yield 🔗

Black gram typically matures in 65-100 days depending on the variety and season. The crop is ready for harvest when the majority of pods turn greyish black, leaves start shedding, and seeds harden inside the pods. Because pods do not mature uniformly, harvesting is usually done in 2-3 pickings. Delay in harvesting can lead to pod shattering, causing significant grain loss.

After harvesting, the pods are sun-dried for 3-4 days and then threshed manually or mechanically. Seeds should be dried to a moisture content of 8-10% for safe storage. Under good management, black gram can yield 12-15 quintals of grain per hectare, though the national average remains considerably lower at around 5-6 quintals due to rainfed conditions and suboptimal practices.

To protect stored grain from bruchids (pulse beetles), traditional methods like mixing black pepper powder, neem oil, or mustard oil with the seeds have proven effective for up to five months of safe storage.

Crop rotation and intercropping 🔗

Black gram fits naturally into rotation systems because of its nitrogen-fixing ability and short duration. Common rotations include paddy followed by black gram, black gram followed by wheat, and black gram followed by jowar. As an intercrop, it can be grown with maize, sorghum, cotton, or sugarcane, making use of available space and improving overall farm productivity. In rice fallows of eastern and southern India, black gram is widely cultivated as a relay crop immediately after the rice harvest, making excellent use of residual soil moisture.

What do you think? With India facing rising demand for pulses and limited arable land, how can small-scale farmers adopt better agronomic practices to close the gap between potential and actual black gram yields? What role could resistant varieties and integrated pest management play in making black gram farming more profitable in your region?

References

1. https://en.wikipedia.org/wiki/Vigna_mungo
2. https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/vigna-mungo
3. https://www.feedipedia.org/node/236
4. https://pfaf.org/user/Plant.aspx?LatinName=Vigna+mungo
5. https://pmc.ncbi.nlm.nih.gov/articles/PMC10822891/
6. https://indiaagronet.com/indiaagronet/crop%20info/black_gram.htm
7. https://www.rarstpt.org/files/rars/package%20of%20practices/Pulses.pdf
8. https://www.nature.com/articles/s41598-024-84990-0
9. https://plantix.net/en/library/plant-diseases/200014/mungbean-yellow-mosaic-virus/
10. https://www.sciencedirect.com/science/article/abs/pii/S0885576524001528
11. https://www.echocommunity.org/en/resources/759594b3-3c1f-4bdf-b52c-5fe6bc5632ff