Origin
This very important bean in the diet of vegetarian Indians was originally found growing in India. It is now widely cultivated in the tropics.
Uses
Black Gram is perhaps the most important pulse crop in Asia because of its versatility of use. The bean is used whole, split, husked, fermented, sprouted or ground into flour which when combined with rice flour is especially valued for baking. After the plants are picked, animals can graze it and it can be plowed under as green manure. It is a legume with a deep root system that binds soil particles together preventing erosion. Its foliage is lush so that when cut and left on the ground, it acts as good mulch.
Cultivation
Black Gram is an annual, warm season crop, which produces pods of 4-6 cm (1.5” - 2.5 in) in 3 months. It tolerates a wide range of soils often succeeding in heavier soils where other crops will not. It can be planted in the late rainy season after maize or soybeans. If the field has previously grown a legume, black gram will freely form nitrogen-fixing nodules on its roots.
Harvesting and Seed Production
The pods turn black when mature though not all will mature at once so 2-4 hand pickings at 10-15 day intervals may be necessary. Plants are often pulled up as the pods mature, left in the field to dry for a week then threshed either by beating with a stick or trod by bullocks. The seeds may be further dried in the sun and stored in a dry area away from rodents.
Pests and Diseases
The threat of various fungi can be overcome by growing black gram in irrigated paddy fields rather than planting the crop in the rainy season.
Cooking and Nutrition
Immature pods of the Black Gram bean can be eaten as a cooked vegetable. Soaked beans can be sprouted or combined with vegetables and spices to make dal, fried crisp as papads or in a fermented batter called idli. The bean is richer in protein than most other grains.
References
http://ecocrop.fao.org/ecocrop/srv/en/cropView?id=2149