IRRIGATION MANAGEMENT

Definition - Irrigation:

     Artificial application of water to soil for proper plant growth and crop production (Israelsen, 1950). The application of water to soil is to assist in the production of crops, especially during stress period. 

HISTORY OF IRRIGATION

      Irrigation has been practiced since time immemorial; nobody knows when it was started but evidences say that it is the foundation for all civilization since great civilization were started in the river basins of Sind and Nile. This civilization came to an end when the irrigation system failed to maintain crop production. There are some evidences that during the Vedic period (400 B.C.) people used to irrigate their crops with dug well water. Irrigation was gradually developed and extended during the Hindus, Muslims and British periods. 

      The Grand Anaicut (KALLANAI) constructed across the river Cauvery is an outstanding example for the irrigation work by a Chola king the great Karikala Cholan during second century. The Veeranarayanan Tank and Gangai Konda Cholapuram tank was constructed during 10th century in Tamil Nadu. Anantaraja Sagar in Andhra Pradesh was constructed during 13th century. Early Mauryan king Samudragupta and Ashoka took great interest in the construction of wells and tanks. Later Moghul kings or North India and Hindu kings of South India focused their attention, in the establishment of canals, dams, tanks etc. British Government initiated their work during 19th century in remodeling and renovation of the existing irrigation system. The Upper Ganga canal, Krishna and Godaveri delta system, Mettur and Periyar dams are the great irrigation structures built by the British rulers. After independence, Irrigation activities have been accelerated and number of multipurpose river valley projects like Bhakra-nangal in Punjab, Tungabhadra in Andhra Pradesh, Damodar Valley in Madhya Pradesh were established.

 IMPORTANCE OF WATER FOR CROP CULTIVATION

• Plants and any form of living organisms cannot live without water, since water is the most important constituent of about 80-90% of most plant cell.
• Water is essential not only to meet agricultural needs but also for industrial purposes, power generation, live stock maintenance, rural and domestic needs etc. But the resource is limited and cannot be created as we require. 

A. Physiological Importance :

• The plant system itself contains about 90% of water.

• Amount of water varies in different parts of plant as follows.

* Apical portion of root and shoot > 90%.

* Stem, leaves and fruits 70–90%

* Woods 50–60%

* Matured parts 15–20%

* Freshly harvested grains 15–20%

• It acts as base material for all metabolic activities. All metabolic or biochemical reactions in

plant system need water.

• It plays an important role in respiration and transpiration.

• It plays an important role in photosynthesis.

• It activates germination and plays an important role in plant metabolism for vegetative and reproductive growth.

• It serves as a solvent in soil for plant nutrients.

• It also acts as a carrier of plant nutrients from soil to plant system.

• It maintains plants temperature through transpiration.

• It helps to keep the plant erect by maintaining plant’s turgidity.

• It helps to transport metabolites from source to sink.

B. Ecological Importance :

• It helps to maintain soil temperature.

• It helps to maintain salt balance.

• It reduces salinity and alkalinity.

• It influences weed growth.

• It influences atmospheric weather.

• It helps the beneficial microbes.

• It supports human and animal life.

• It helps for land preparation like ploughing, puddling etc., weeding, fertilizer application etc., by providing optimum conditions.

Necessity of irrigation :

i) Uncertainity of monsoon rainfall: 80% of rainfall in India is received during monsoon period. Monsoon rainfall is very uncertain. So irrigation is very important to supply water to plants also and when needed.

ii) Uneven distribution of rainfall: To compensate the uneven distribution in an area, supplemental irrigation is needed.

iii) Effect of winter rainfall (N India)/ Effect of SWM in S. India: Supplemental irrigation is inevitable in the regions due to poor rainfall.

iv) Cultivation of high yielding crops: High yielding crops produce heavy biomass and economic yield. Higher biomass need more water for its production. Hence supplementation of water as irrigation is essential.

v) Difference in water holding capacity of the soil: Sandy soil - low WHC – frequent irrigation. Clay soil - high WHC - frequency is less.

SOURCES OF WATER

     Rainfall is the ultimate source of all kind of water. Based on its sources of availability, it can be classified as surface water and subsurface water. 

Surface Water 

     It includes (including rainfall and dew) water available from river, tank, pond, lake etc. Besides, snowfall could able to contribute some quantity of water in heavy snowfall areas like Jammu, Kashmir and Himalaya region.

Sub Surface Water

     It includes subsurface water contribution, underground water, well water, etc. 

India’s Water Budget 

• Total geographical area = 328 m.ha.
• Average annual rainfall = 1190 mm
• In m.ha metre = 1190 × 328 = 392 m.ha.m
• Contribution from snowfall = 8 m.ha.m.
• Total = 400 m.ha.m.