Lecture 34
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Lecture 34 Leaching requirements - irrigation and drainage water quality recycling of drainage water for irrigation. Extensive areas of land in the arid and semi arid regions of India have gone out of cultivation due to the rise of water table and accumulation of salt.

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Lecture 34

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Lecture 34

Lecture 34

Leaching requirements - irrigation and drainage water quality recycling of drainage water for irrigation


Lecture 34

  • Extensive areas of land in the arid and semi arid regions of India have gone out of cultivation due to the rise of water table and accumulation of salt.

  • Excessive irrigation and poor water management are the chief causes of water logging and salt build-up.

  • An accumulation of salts in soils leads to unfavorable soil-water- air relationships and decreases crop production.

  • Gradually, the land goes out of cultivation, unless remedial measures are under taken.


Lecture 34

LEACHING

Leaching is the process of removal of soluble material by the passage of water through soil.

LEACHING REQUIREMENT

It is the minimum amount of irrigation water that must be drained through the crop root zone to control the soil salinity at the given specific level.


Lecture 34

  • LEACHING METHODS

  • By ponding an appreciable depth of water on the soil surface by means of dikes or ridges

  • Rectangular checks and level borders are used when the land is flat.

  • Contour checks can be used when the land slope is considerable.

  • The effectiveness of leaching by furrows is limited.

  • Sprinkling is an effective method for leaching, especially when soils are cracked or are highly permeable.

  • Intermittent ponding is superior to continuous ponding for effective leaching.


Lecture 34

  • The efficiency of leaching depends on

  • The amount of water applied,

  • Uniformity of water distribution, and

  • The adequacy of drainage


Lecture 34

For surface irrigation method including sprinkler

Where,

ECw = Electrical conductivity of the irrigation water, dS/m

ECe = Electrical conductivity of the soil saturation extract for a given crop proportional to the tolerable degree of yield loss


Lecture 34

For drip irrigation method

Where,

ECw = Electrical conductivity of the irrigation water, dS/m

Max.ECe =MaximumtolerableElectrical conductivity of the soil saturation extract for a given crop


Lecture 34

  • Salinity management techniques

  • Frequent irrigation

  • Crop selection

  • Preplanting irrigation

  • Higher Seed rate

  • Blending with good quality irrigation water

  • Irrigation rotation with good and poor water

  • Land grading

  • Deep ploughing and subsoiling

  • Drainage

  • Rain water management


Lecture 34

  • Drainage water use

  • Used for irrigation by mixing with canal water

  • Dispose off the water by gravity/ by lift irrigation

  • Evaporation tanks

  • Bio-drainage

  • Brackish water fish culture


Lecture 34

HE WHO PROVIDES WATER DESERVES TWO NOBEL PRIZES

ONE FOR PEACE AND THE OTHER FOR SCIENCE

-John F. Kennedy-


Lecture 34

LET US WORK TOGETHER TO MANAGE AVAILABLE WATER


Lecture 34

Thank you...

Water is precious… conserve it…


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