"Agro-climatic Zones of Tamil Nadu 1,2 Tamil Nadu is classified into the following seven distinct agro-climatic regions (Table and Figure). These are: Southern zone, North Eastern zone, Cauvery Delta zone, North Western zone, Western zone, High Altitude and Hilly zone, as well as High Rainfall zone. Table Tamil Nadu Agro-climatic Zone 2 Zones Sl. No. Area (Km ) Area (%) Southern 1 36398.64 27.99 North-Eastern 2 30975.84 23.82 Cauvery-Delta 3 24768.55 19.04 North-Western 4 18143.22 13.95 Western 5 15568.35 11.97 High-Altitude and Hilly 6 2531.17 1.95 High-Rainfall 7 1672.22 1.29 Tamil Nadu 130058.00 100.00 1 District Specific Technology Inventory For Tamil Nadu and Puducherry; (2007)Published by Directorate of Extension Education, Tamil Nadu Agricultural University, Coimbatore and Zonal Co Ordinating Unit-Zone VIII, Indian Council of Agricultural Research Herbal, Bangalore. 2 Agricultural Department Policy Notes; (2010)Published by Government of Tamil Nadu.FigureSouthern Zone The southern zone consists of Tirunelveli, Virudhunagar, Ramanathapuram, Thoothukkudi, Sivaganga, Madurai (Tirumangalam, Madurai South, Madurai North and Melur taluks) and Dindigul (Natham and Dindigul taluks). This agro climatic zone extends between 8° N to 10° 55' N latitudes and 77° E to 79° 50' E longitudes. It covers an approximate area of 36,398.64 sq. km which is equivalent to 27.99 per cent of the area of the state. The annual rainfall in this zone varies from 700-850 mm. The average summer temperature ranges from 22.54°C to 29.95° C and the winter temperature from 20.22°C to 28.74°C. Tambiraparani, Arumanadhi, Nambiar and Vaipar are the important rivers of this zone. About 45 % of the area of this zone is under cultivation. The major crops Paddy, Sugarcane, Oilseeds, and Cotton. Cropping Seasons of this zone are Samba (spreading between August and January), Navarai (spreading between December and March), and Late Thaladi (spreading between October and February). North Eastern Zone This zone covers the districts of Thiruvallur, Kancheepuram, Cuddalore (excluding Chidambaram and Kattumanarkovil taluks), Viluppuram, Tiruvannamalai, Vellore district and parts of the Perambalur district and between 8°50' N to 13°.20' N latitudes and 76° 15' to 80° 22' E longitudes. It covers an approximate area of 30975.84 sq. km. which is equivalent to 23.82 per cent of the area of the state.The annual rainfall in this zone varies from 800-1400 mm. The average summer temperature ranges from 28.2° C to 38.9° C and the winter temperature from 19.5° C to 24. 8°C. The major rivers are Polar, Ponniar, Cheiyear, Vellar, Thenpennai, Manimuthar and Komugi. Majore dams used for irrigation are Mettur, Sathur, Veedur, Komugi, Manimuthar and Wellington. Kancheepuram district which is known as “Lake District” and also where the popular “Madhurandhagam lake” is presents comes under this zone. About 50.5% of the area of this zone is under cultivation. The major crops are Paddy, Coarse grain, Sugarcane, and Groundnut. Cropping Seasons of this zone are Samba (spreading between August and January), Thaladi (spreading between September and January), Navarai (spreading between December and March), and Sornavari (spreading between April and July). Cauvery Delta Zone This zone includes Thanjavur district, Musiri, Tiruchirappalli, Lalgudi, and Kulithalai taluks of Tiruchirappalli district, Aranthangi taluk of Pudukkottai district and Chidambaram and Kattumannarkoil taluks of Cuddalore and Viluppuram district. It lies in the eastern part o of Tamil Nadu between 10 N to 11°30' N latitudes and 78°15' E to 79°45' E longitudes. It covers an approximate area of 24768.55 sq. km. which is equivalent to 19.04 per cent of the area of the state. The annual rainfall in this zone varies from 1155 - 1310 mm. The average summer temperature ranges from 20°C to 42°C and winter temperature from 10°C to 31°C. The important rivers are Cauvery, Vennaru, Kudamuruti, Paminiar, Arasalar and Kollidam. Themajor dams utilized by this zone are Mettur and Bhavanisagar. Thanjavur district, which is known as “Rice Bowl” of Tamil Nadu, comes under this zone. About 60.2 % of the area of this zone is under cultivation. The major crops are Paddy, Sugarcane, Oil seeds, and Cotton. Cropping Seasons of this zone are Samba (spreading between August and January), Navarai (spreading between December and March), Karuvai (spreading between June and Septembrer). North Western Zone The North Western Zone comprising the districts of Dharmapuri, Krishnagiri, Salem and Namakkal (excluding Tiruchengode taluk)and Perambalur taluk of Perambalur. It is situated between 11° N to 12°55' N latitudes and 77° 28' E to 78° 50' E longitudes. It is covers an approximate area of 18,143.22 Sq. km. equivalent to 13.95 per cent of the area of the state. The annual rainfall of this zone is varies from 650-900 mm. The average summer temperature ranges from 20°C to 42°C and the winter temperature from 10°C to 31°C. The major Rivers of this zone are Cauvery, Thenpennai and Manimuthar. Mettur and Krishnagiri are the major dams in this zone. About 56.3 % of the area of this zone is under cultivation. The major crops are Paddy, Coarse grain, Tobacco, Sugarcane, and Cotton are the major crops of this zone. Cropping Seasons of this zone are Samba (spreading between August and January), Navarai (spreading between December and March), Kar (spreading between May to August). Major crops are grown in this zone are Rice, Tapioca, Oilseeds, Red millet, Horse gram and Cotton.Western Zone This zone covers Erode, Coimbatore, Tiruchengode taluk of Salem district, Karur taluk of Tiruchirappalli district and Northern part of Madurai. The zone extends between 9° 30' N to 12° N latitudes and 70° 30' E to 78° E longitudes. It is covers an approximate area of 15,568.35 sq. km which is equivalent to 11.97 per cent of the area of the state. The annual rainfall in this zone varies from 700-800 mm. The average summer temperature ranges from 22.61°C to 31.51°C and the winter temperature from 19.78 °C to 29.79°C. The Cauvery, Noiyal, Bhavani, Uppar, Sirvani and Amaravathi are the major rivers and Mettur, Bhavanisagar and Amaravathi are the major dams lying in this zone. About 44.5 % of the area of this zone is under cultivation. The major crops are grown in this zone are Rice, Gram, Sugarcane, and Cotton. Cropping Seasons of this zone are Samba (spreading between August and January), Thaladi (spreading between September and January), and Navarai (spreading between December and March). High Altitude and Hilly Zone This zone covers the hilly regions, namely, Nilgiris, Kodaikanal, Shevroy, Elagir Javadhi, Kollimalai, Pachamalai, Yercaud, Anamalais, Palani and Podhigaimalai. The Nilgiris district known as "The Queen of Hill Stations" is situated at an elevation of 900 to 2636 meters above MSL. Approximately 65% of the geographical area of this district lies at an altitude of above 1800-2500 meters from MSL and the remaining 35% at a lower altitude. This zone covers an approximate area of 2,531.17 sq. km. which is equivalent to 1.95 per cent of the area of the state."