Agronomy – definition – meaning and scope. Agro-climatic zones of India and Tamil Nadu – Agro ecological zones of India One Liner - Examups

Agronomy is the branch of agricultural science focused on crop production and field management.
Derived from Greek, ‘agros’ means field and ‘nomos’ means management.
Agronomy involves the scientific study of principles for growing crops in different environmental conditions.
Principles of Agronomy aim to optimize environmental factors for crop productivity.
Scope of Agronomy includes crop management, soil management, water management, pest control, and sustainable farming practices.
Agronomy helps identify the best seasons for planting crops and methods for maximizing yield.
It plays a key role in managing resources like water and fertilizers efficiently to improve crop production.
Agronomists design methods to reduce the environmental impact of agricultural practices.
Agronomy supports intensive cropping systems to increase productivity.
It provides solutions for overcoming moisture stress in dryland agriculture.

India is classified into 15 agro-climatic zones by the Planning Commission based on climate, cropping patterns, and rainfall.
ICAR (Indian Council of Agricultural Research) has classified India into 127 agro-climatic zones.
Tamil Nadu has 7 agro-climatic zones:
- North Eastern Zone
- North Western Zone
- Western Zone
- Cauvery Delta Zone
- Southern Zone
- High Rainfall Zone
- Hilly Zone
North Eastern Zone in Tamil Nadu gets an annual rainfall of 1054 mm and has both monsoon influences.
North Western Zone is dry, with 825 mm annual rainfall, and is drought-prone.
Western Zone has 718 mm rainfall, with warm temperatures ranging from 19°C to 35°C.
Cauvery Delta Zone has the highest rainfall among Tamil Nadu’s zones, at 1078 mm.
Southern Zone is prone to drought and receives only 776 mm of rainfall annually.
High Rainfall Zone (Kanyakumari) receives 1469 mm of rainfall, with a tropical monsoon climate.
High Altitude and Hilly Zone includes regions like the Nilgiris, with rainfall varying from 850 mm to 4500 mm.

Agro-ecological zones are regions distinguished by climate, soils, and vegetation that influence crop growth.
The National Bureau of Soil Survey and Land Use Planning (NBSS & LUP) has classified India into 20 agro-ecological regions.
Arid Ecosystems have regions with a growing period (LGP) of less than 90 days, such as parts of Rajasthan and the Deccan Plateau.
Semiarid Ecosystems have an LGP between 90-150 days and are found in regions like Telangana and Eastern Ghats.
Subhumid Ecosystems have an LGP of 150-180 days and are found in areas like the Eastern Plateau and parts of the Western Himalayas.
Humid-Perhumid Ecosystems have LGPs greater than 210 days, found in Bengal, Assam, and the Eastern Himalayas.
Coastal Ecosystems include regions like the Eastern Coastal Plain and Western Ghats with LGP ranging from 90-210+ days.
Island Ecosystems such as the Andaman and Nicobar Islands have a per-humid climate with high rainfall and an LGP of over 210 days.
Western Himalayas have shallow soils and a cold climate with an LGP of under 90 days.
Deccan Plateau features arid soils with a hot climate and an LGP of less than 90 days.

Soil Science helps understand soil properties and their impact on crop growth.
Agricultural Chemistry involves the chemical processes in crops, fertilizers, and pesticides.
Crop Physiology studies the life processes of crops to optimize growth conditions.
Plant Ecology examines the relationship between crops and their environment.
Biochemistry reveals biochemical processes within plants that affect crop yields.
Economics helps agronomists assess cost-efficiency in crop production and farm management.

Agronomists work on crop production problems and recommend practices to optimize yields.
They aim to achieve maximum production at minimal costs by applying scientific knowledge.
Crop management decisions such as selecting suitable crops and varieties for different seasons and soils are made by agronomists.
Agronomists design and recommend efficient cultivation methods such as broadcasting, transplanting, and dibbling.
They determine nutrient requirements and timing of fertilizer application for optimal growth.
Agronomists develop integrated weed management strategies using mechanical, chemical, and cultural methods.
Irrigation management is optimized by agronomists to improve water use efficiency.
Agronomists develop suitable crop sequences and patterns to maximize productivity.
They also decide on the timing of harvest to avoid yield loss.

ICAR’s agro-climatic zone classification aids in effective resource management and cropping strategies.
Western Himalayan Zone includes Jammu and Kashmir and Himachal Pradesh with cold climates.
Eastern Himalayan Zone has high rainfall and is prone to soil erosion and floods.
Lower Gangetic Plains Zone is prone to flooding, with fertile alluvial soils.
Middle Gangetic Plains Zone has high rainfall and extensive irrigation.
Upper Gangetic Plains Zone consists of districts in Uttar Pradesh with potential for groundwater utilization.
Trans-Gangetic Plains Zone has the highest net sown area and irrigation.
Eastern Plateau and Hills Zone has shallow soils and undulating topography.
Central Plateau and Hills Zone is characterized by low irrigation and rainfed agriculture.
Western Plateau and Hills Zone has moderate rainfall and irrigation through canals.
Southern Plateau and Hills Zone is semi-arid with dryland farming practices.
East Coast Plains and Hills Zone includes coastal areas with alluvial soils and canal irrigation.
West Coast Plains and Ghats Zone has varied rainfall and crop patterns across Tamil Nadu, Kerala, and Maharashtra.
Gujarat Plains and Hills Zone is arid with low rainfall and limited irrigation.
Western Dry Zone is characterized by sandy desert soils and erratic rainfall, common in Rajasthan.
Islands Zone includes the Andaman & Nicobar Islands and Lakshadweep with tropical and monsoon climates.