Leaching requirements - irrigation and drainage water quality

Document Sample
Leaching requirements - irrigation and drainage water quality Powered By Docstoc
					            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.
• 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.
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.
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.
The efficiency of leaching depends on
1.The amount of water applied,
2.Uniformity of water distribution, and
3.The adequacy of drainage
For surface irrigation method including sprinkler


                     ECw
             LR 
                  5ECe  ECw
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
 For drip irrigation method

                       ECw
                LR 
                     2Max.ECe
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
Salinity management techniques
1. Frequent irrigation
2. Crop selection
3. Preplanting irrigation
4. Higher Seed rate
5. Blending with good quality irrigation water
6. Irrigation rotation with good and poor water
7. Land grading
8. Deep ploughing and subsoiling
9. Drainage
10.Rain water management
Drainage water use
1. Used for irrigation by mixing with canal water
2. Dispose off the water by gravity/ by lift
   irrigation
3. Evaporation tanks
4. Bio-drainage
5. Brackish water fish culture
HE WHO PROVIDES WATER DESERVES TWO NOBEL PRIZES
         ONE FOR PEACE AND THE OTHER FOR SCIENCE
                              -John F. Kennedy-
LET US WORK
TOGETHER TO
MANAGE
AVAILABLE WATER
Water is precious… conserve it…

				
DOCUMENT INFO
Shared By:
Categories:
Tags:
Stats:
views:9
posted:8/20/2012
language:
pages:14