Contents: 1. Importance of agriculture. 2. Tamil Nadu agro-climatic zones. 3. Agronomy. 4. Soil science. 5. Entomology. 6. Nematology. 7. Plant pathology. 8. Plant breeding. 9. Plant physiology. 10. Seed science and technology. 11. Agricultural extension. 12. Agricultural economics. 13. Agricultural legislations. 14. Informatics in agriculture. 15. Agricultural engineering. 16. Environmental science. 17. Biotechnology in crop improvement. 18. Horticulture. 19. Mushroom production. 20. Sericulture. 21. Apiculture. 22. Crop production guide. 23. Government schemes on agriculture development. 24. Food science. 25. Model questions. 26. Application technique spray volume. 27. Annexures. Agriculture is one of the key source for economic sustinance and all round progress of our country, were more than 70 percent of Indian population is dependent on agriculture. India with only 2.5 percent land area, 4 percent fresh water and 1 percent forest cover has to support about 17 percent of World’s population (Over 1.18 Billion). Science based agriculture adapted for the past four decades in the country has brought appreciable change in the food production scenario. Over the years a six fold increase in food grain production has transformed food scarcity into food sufficiently. Competitive examinations including agriculture as a major subject in a routine procedure of recruitment and admissions for higher position and education. A sincere effort has been made by the authors to present this book in a most easy, short and understandable language for the benefit of students who are preparing for competitive examinations in agriculture as well as in other subjects.