Ranjit Tirtha and Gopal Krishan (1996) on the basis of first ranking crops have identified 9 regions. These include rice, wheat, jowar, bajra, maize, gram, groundnut, and cotton and ragi regions in addition to the areas of shifting cultivation.
Rice, region occupying the north-eastern part and coastal plains, commands the largest area. It has double and multiple cropping in well-watered alluvial parts of the Lower Ganga Plain. Similarly it occupies monocultural position in the coastal plains, the Lower Ganga Plain, the Assam Valley, Tripura and the Kaveri delta where ideal environmental conditions are available for the crop. Secondary crops in the rice region are jute, oilseeds, pulses and tea.
Tea is important in the hills adjoining the Assam Valley and in Darjeeling and Jalpaiguri districts of West Bengal. A rice-coffee combination is restricted to the plantations in the hills of Coorg and Karnataka.
The pulse-jowar-rice combination is particularly noteworthy in the Krishna Delta, where rainfall is less than 125 cm annually. Oilseeds are videly grown as a second or third ranking crop in the rice region of southern Bihar and the Mahanadi Delta. Maize and wheat in association with rice occupy a major portion of cropland in the Kashmir Valley and the Tarai region in Uttar Pradesh.
Cotton is a second crop in Meghalaya and along the northern coast of Maharashtra. Gram is important in the Lower Ganga Plain and in western Uttar Pradesh.
Wheat is a first ranking crop in the Punjab Plain, Upper Ganga Plain and western Rajasthan. Within the wheat region, maize and barley are second crops in the hills of Himachal Pradesh, while cotton is significant in areas of irrigation in western and central districts of Punjab as a kharif crop. Bajra holds a secondary position in the drier districts of south Punjab and south Haryana.
Jowar as a first ranking crop occupies an extensive area over Maharashtra and Karnataka plateau, Rayalseema, eastern Rajasthan and western Madhya Pradesh. Jowar and wheat extends from east Rajasthan and the Malwa Plateau to the drier central parts of the Deccan Plateau and as far south as north Karnataka. Similarly jowar and cotton are important rain-fed kharif crops in the Deccan Lava Region, whereas oilseeds and groundnuts occupy drier portions of the jowar region.
Bajra as a first ranking crop forms a monocultural region in the west Rajasthan. Gram is a first-ranking crop in many districts of north central India, northern Rajasthan, southern Punjab, Haryana and south-western Uttar Pradesh. Maize region is confined to the Aravalli Hills of southern Rajasthan with barley as a second crop.
In the southern part of the Deccan Peninsula, ragi is a major crop on the uplands of south Karnataka and north Tamil Nadu where oilseeds and groundnuts are secondary crops.
In areas where grain is not a leading (first ranking) crop, a leguminous crop such as gram or oilseeds, usually predominates. Groundnut is a dominant crop in Gujarat and in one district of Andhra Pradesh. Similarly, cotton is a leading crop in the Deccan Lava region of Gujarat, north Maharashtra and southern Madhya Pradesh (Tirtha and Krishan, 1996, pp. 171-173). Areas of shifting cultivation are confined to the tribal areas of the north-east, Dandakaranya and southern Sahayadris.