According to R. L. Singh agricultural regions of the country are justifiably crop combination regions. The leading crops are rice, wheat, millets, maize, gram, cotton, groundnut and coconut. Thus we have 8 regions of first order based on first ranking crops, 27 regions of second order based on first 2 ranking crops and 48 regions of third order based on first 3 ranking crops (Singh, R.L., 1971, p. 22).
1. Rice Region
It includes major part of the north-east, East Uttar Pradesh, Bihar, and West Bengal, Orissa, Chhattisgarh, coastal Andhra Pradesh, coastal Tamil Nadu and western coastal plain. The micro-level variation in geographical conditions leads to following 21 third order agricultural regions.
2. Wheat Region
This region extends over north-western India covering the parts of Jammu and Kashmir, Himachal Pradesh, eastern Haryana, western Uttar Pradesh and western Madhya Pradesh. It is divided into 7 third order agricultural regions.
2.1 Wheat, maize, rice
2.2 Wheat, sugarcane, rice
2.3 Wheat, rice, gram
2.4 Wheat, millets, gram
2.5 Wheat, rice, maize
2.6 Wheat, gram, millets
2.7 Wheat, millets, gram
3. Gram Region
This crop-combination region lies over the borders between Uttar Pradesh and Madhya Pradesh, Punjab and northern Rajasthan. It has three third- order regions.
3.1 Gram, wheat, maize
3.2 Gram, millets, wheat
3.3 Gram, wheat, maize
4. Millets Region
This is the second largest crop-combination region of the country after the rice region. This
4.4 Millets, cotton, groundnut
4.5 Millets, cotton, groundnut
4.6 Millets, wheat, oilseeds
4.7 Millets, cotton, oilseeds
4.8 Millets, rice, oilseeds / gram
4.9 Millets, groundnut, oilseeds
4.10 Millets, groundnut, cotton
4.11 Millets, groundnut, rice
4.12 Millets, rice, tobacco, oilseeds
5. Cotton Region
This region incorporates eastern part of Maharashtra (Nagpur, B handara, Wardha, Chandrapur and Gadchiroli districts), and southern Gujarat (Kheda, Panchmahal, Vadodara, Bharuch, Surat and Valsad districts). It is divided into two third-order regions.
5.1 Cotton, millets, rice
5.2 Cotton, millets, wheat
6. Groundnut region
This includes Kachchh and Kathiawar areas of Gujarat where groundnut, millets and cotton forms the typical third-order crop combination.
7. Maize Region
Maize is the first ranking crop in the semi-arid tracts of eastern Rajasthan and constitutes a third- order combination with wheat and gram.
8. Coconut Region
This region occupies the south and central parts of Kerala where coconut is the dominant crop. It has only one third-order region consisting of coconut, rice and spices.
9. Shifting Cultivation
Shifting cultivation is carried over by the tribal’s in the north-eastern (Arunachal Pradesh, Nagaland, Mizoram, Manipur and Tripura), central (Orissa and Madhya Pradesh) and Western Ghats of India.
10. Plantation Agriculture
Plantation agriculture growing tea, coffee and rubber finds place in the hilly areas of the North- East, southern Sahyadris and hills of Himachal Pradesh and Uttaranchal. It has typical identity in the agricultural landscape of the country with sole objective of commercialization and export.