B .L.C. Johnson (1979), on the basis of principal crops and crop associations, has demarcated 15 major crop association regions in India. Besides, there are two other regions belonging to the humming cultivation and plantation crops.
1. Rice Mono Culture
This region includes Assam, West Bengal, southern Bihar, Orissa, and eastern Madhya Pradesh, and north-eastern Andhra Pradesh, coastal plains of Maharashtra, Goa, Karnataka and Kerala. It is the biggest agricultural region of the country where amount of annual rainfall is more than 125 cm and rice is the predominant crop and main staple food. It is further divided into 5 sub-regions:
Eastern India-it stretches over heavy rainfall areas (over 200cm) of the Ganga-Brahmaputra south to the Kaveri delta with well developed irrigation system are typical rice growing region of the Peninsula. The cropping pattern lacks diversity except at a minor level. Rabi rice reaches 15 per cent TSA in the Godavari-Krishna deltas and Nellore. Kanniyakumari in the extreme south is an outlier of this sub-region having 94 per cent TSA under rice.
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Western Coast-With the exception of Thiruvananthapuram and Kollam districts of Kerala and entire West Coast up to Valsad in Gujarat is a region dominated by Kharif rice, relieved in Kerala by subsdiary tapioca, and by kharif pulses and jowar northwards. Tree crops decline in importance northwards: coconuts and areca nuts on the coastlands and the more tolerant cashew on the coastal platforms. Plantation crops are confined to the southern part of the region, extending little further north than Coors.
Andaman-Nicobar Islands-Rice reaches nearly monocultural status in the Andaman and Nicobar islands. Coconuts and arecanuts are important, and rubber, coffee, oil palm and various spice trees are also grown.
2. Rice-Maize Region
Rice, in combination with maize, is a substantial kharif crop in two widely separated and topographically dissimilar areas.
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Kashmir Valley-In Kashmir valley maize reaches 31 per cent TSA occupying the slopes and gravel terraces, with rice, 49 per cent, on the better alluvium of the Jhelum flood plain. Rabi mustard and wheat are other subsidiary crops of the region.
Darjeeling-Here rice, 53 per cent TSA forms combination with maize, 28 per cent TSA and ragi. The area is also famous for tea plantation along the hill slopes.
3. Rice-Wheat Region
This region occupies whole of the Ganga Plain from Punjab to the borders of West Bengal. In the western part wheat is more important than rice but converse is true in the east.
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It includes Bihar and Uttar Pradesh (except west U.P.) whose western limit is formed by 100 cm isohyet. In the Tarai region maize is a subsidiary crop added to the combination.
It occupies western Uttar Pradesh, northern Madhya Pradesh, northern Haryana and Punjab. Here wheat is the first ranking crop accompanied with rice and various subsidiary crops. Sugarcane is an important crop in the sub-montane plain of the western Uttar Pradesh while maize comes next to wheat-rice in northern Haryana and Amritsar and Gurdaspur districts of Punjab.
On the finer soils of Firozpur canal irrigation supports intensive cultivation of wheat-rice with kharif cotton and rabi pulses as minor crops. In Uttaranchal rice and wheat with ragi as a kharif millet are grown in the terraced fields. Temperate vegetables and potatoes are grown throughout the region in scattered patches which are in great demand in nearby urban centres.
4. Wheat-Maize Region
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This occupies Jammu and Kashmir, Himachal Pradesh and northern parts of Haryana and Punjab. Here rice is relegated to secondary or even negligible position after wheat-maize.
5. Wheat-Millets Region
This is transition area between the wheat-rice region to the east and the area of bajra dominance to the west.
In a great arc extending from Ganganagar at the northern tip of Rajasthan, eastwards through southern Haryana and south-east from Delhi in a broad stretch reaching to the Maharashtra border, wheat is the more important crop in association with Jowar and Bajra. Irrigation compensates for semi- aridity in the northern part, while southwards rainfall becomes relatively more reliable. Rabi oilseeds and pulses are commonly found in secondary roles.
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Within and west of the arc (5.1) kharif millets, increasingly bajra, assume first place as rainfall and its reliability decrease, and as soils become sandier and stonier in the Aravalli belt. Subsidiary crops include kharif oilseeds, pulses and maize.
6. Kharif Millets
This includes western Rajasthan, Kachchh and Ladakh region of Jammu and Kashmir. While former is dominated by bajra the latter (Ladakh) supports ragi as the kharif crop.
This region incorporating parts of west Rajasthan and Kachchh is dominated by bajra as the
main food crop. Pulses are subsidiary crops while cattle rearing play a vital role in the economy of the region.
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Kalakh area of Jammu and Kashmir is a part of cold desert where ragi dominates as the kharif crop with winter wheat, hardy barley and oilseeds as secondary crops. Here also the economy leans heavily on transhumance of sheep and yaks.
7. Maize and Wheat / Rice
Maize associated with wheat and barley in the north or with rice in the south characterizes the agriculture of the south-central Aravalli Hills from southern Rajasthan into western Gujarat. Secondary crops include kharif millets, cotton, oilseeds and rabi pulses and oilseeds which indicate the diversity of the crop environment.
8. Cotton-Millets
This includes red/roils region of Maharashtra, Gujarat and northern Karnataka. Here millets replace wheat or rice as the main food crop while kharif oilseeds are subsidiary crops.
This includes main cotton belt of Maharashtra and Gujarat characterised by low cropping intensity and dominance of kharifcrops. Groundnut is a main crop while rabi pulses, oilseeds and wheat acquire only secondary status.
The ‘little’ cotton belt of Karnataka is in a region of deep regur cotton and kharif jowar, in one district rabi jowar also, stand in primary position in the crop-association, with as many as five crops at secondary level, including kharif pulses and oilseeds, rice and wheat.
9. Jowar Region
Separating the two cotton belts on the Maharashtra-Karnataka Deccan lava plateau is the jowar region par excellence. Rice and sugarcane in the irrigated areas; rabi wheat, pulses and oilseeds; and kharif cotton, pulses and oilseeds are other subsidiary crops.
10. Jowar-Oilseeds Region
Kharif jowar combines with kharif oilseeds, particularly groundnuts, in the Andhra Deccan region south of Hyderabad. Where irrigation is available rice enters the combination (in the south).
Els where kharif pulses are widely grown, chilies and tobacco as secondary crops.
11. Jowar-Rice Region
This region follows the Wainganga val and the middle Godavari to above its delta, incorporates the low hilly country through Kham to the sea at Vishakhapatnam. This is a transi /.one where kharif sometimes rabi jowar, and reach a balance with a number of subsidiary.
12. Millets-Rice Region
This region extends from central Kama to the dry coast of southern Tamil Nadu where millets and rice are in association. Among the mill ragi is preferred in the north and jowar-bajra into south. Rice cultivation largely depends upon I availability of irrigation facility. Cotton is an additional ingredient in the south while coconuts area nuts, as subsidiary crops, are locally important.
13. Tapioca-Rice Region
Thiruvananthapuram and Kollam in south Kerala have a crop-association of tapioca within Tree crops are present in abundance; coconut areca nuts, and rubber in the lowlands, and at high levels, coffee, cardamoms and tea.
14. Potato-Rice Region
This occupies Nilgiris district of Tamil Na where potato and rice constitute 56% and 25% of TSA respectively. Temperate vegetables do well this hill country, much of it over 2000 m. Spices, rag and tapioca add to the variegated pattern of fie crops in a landscape interspersed with tea, coffee cinchona and eucalyptus plantations.
15. Coconut region
The economy of Lakshadweep, the group coral islands in the Arabian Sea, is based on coc nuts and tuna fishing. Field cropping is practical non-existent.