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

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Lecture 34 Leaching requirements - irrigation and
drainage water quality recycling of drainage
water for irrigation
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• 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.

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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.
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• 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.

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• The efficiency of leaching depends on
• The amount of water applied,
• Uniformity of water distribution, and
• The adequacy of drainage

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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
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For drip irrigation method
Where, ECw Electrical conductivity of the
irrigation water, dS/m Max.ECe Maximum
tolerable Electrical conductivity of the soil
saturation extract for a given crop
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• 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

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• 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

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HE WHO PROVIDES WATER DESERVES TWO NOBEL
PRIZES ONE FOR PEACE AND THE OTHER FOR SCIENCE
-John F. Kennedy-
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LET US WORK TOGETHER TO MANAGE AVAILABLE WATER
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Thank you...
Water is precious conserve it