Water Logging
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Transcript of Water Logging
WATERLOGGING
Dr. M. DhakshinamoorthyProfessor (SS&AC)
IMTI, Trichy
CAUSES FOR WATER LOGGING
Poor natural drainage
Heavy downpour coupled with poor natural
drainage
Spilling of rivers and continuous submergence
Poor irrigation management without
considering soil properties
Heavy seepages from canal, distributaries and
water sources
Development activities (road/bridges/railway line)
choking of natural drains
Poor drainage system
Poor upkeep of water sheds
Hydraulic pressure from upper irrigated areas/
Seepage in low lying areas
EFFECTS OF WATER LOGGING
Accumulation of excess soluble salts in shallow
water table
Reduction of soil strength
Oxygen diffusion is 10,000 times lesser then
running water
Redox potential is – 400mV
Accumulation of Co2 , CH4, HCo3-, Co3
2- and H2S
Change in the soil pH and stabilization
(Neutral)
Anaerobes microbes exists with low energy
level
Reduced nutrient availability
Accumulation of toxicants (H2S, CH4)
Poor crop growth/nutritional disorders and
yield reduction
ILL EFFECTS ON SOIL
Lack of aeration (Oxygen)
Reduced soil temperature
Creation of salinization
Inhibiting/Reducing microbial activity
Problems in managing the soil
Obstruction to seed germination /growth
Excess weed growth
Affecting salt and water balance
Damage to building, wells, pipelines, roads etc.
Water logging causes soil salinity
Poor drainage
Sea water intrusion
Districts Ill drained & waterlogging
Salinity/Sodicity
Soil series
Area (ha) Soil series Area (in ha)
Thanjavur
Kallivayal
482(0.14%)
Kallivayal 482 (0.14%)
Thiruvarur
Kallivayal
1535 (0.8%)
Kallivayal & Kivalur
3727 (1.9%)
Naga-pattinum
Kallivayal & Naga-pattinum
10486 (4.6%)
Kallivayal, Kivalur & Nagapattinum
36845 (16.3%)
SALINITY AND WATERLOGGING IN THE COMPOSITE THANJAVUR Dt.
•Provision of surface drainage
•Lining the canals to avoid seepage and associated Stalinization
•Harvesting of the run off water and its recycling in the post rainy season
•Increasing the carrying capacity of the drainage channels by strengthening the bunds
MANAGEMENT OF WATERLOGGED SOILS
•Conjunctive use of ground water, canal water and stored rainwater to arrest/reverse the rise of water table
•Provision of check dams to prevent the sea water intrusion
•Growing saline resistant, high yielding deep water rice varieties (ADT40, CO43, TRY 1 & 2, IR 36, IR 42, Pokkali)
MANAGEMENT OF WATERLOGGED SOILS
• Irrigation induced water logging
• Poor quality irrigation water
• Salinity due to prawn culture
• Sea water intrusion
OTHER CONSTRATINTS
Coastal Soils
Characteristics
Clay < 10 % Sand > 90 %
Very low water retention capacity
pH varies from 7.9 to 8.1
EC is generally < 0.23
CEC 3.8 to 8.4 me/100g
High CaCO3 and SOM
Management of Coastal soilsProvision of Protective Embankment
Levelling the land to provide uniform drainage of excess water
Avoid summer fallow to avoid sea water intrusion
Mulching during post harvest period to improve soil properties
Lowering water table through deep drains
Grow Rice varieties that tolerate water logging and salinity
Transplant more seedlings per hill
Apply suitable amendments as and when necessary
Management of Coastal soils
Low pH (3 – 4) and medium to high salinity
High OM decomposition in brackish water under anaerobic conditions results in Iron Pyrites
Pyrites on oxidation give H2SO4 lowering soil pH
Found in Sri Lanka, Indonesia, Thailand, Vietnam, India, Senegal,
Acid Sulphate soils
Toxic concentration of Fe and Al
Low availability of Ca and P,
Shallow water table resulting in water logging,
Low base saturation.
Acid Sulphate soils
Water logged Soils – Suitable for Rice only
Never drain these soils – Pyrites gets oxidized to sulphuric acid – pH further lowered
Apply lime to increase pH and reduce toxicity of Fe and Al
Heavy doses of lime 5 – 10 t/ha every 2 to 3 years
Acid Sulphate soils
Soil Physical Constraints
Slow permeable soils
Excessive permeable soils
Sub soil hard pan
Shallow soils
Fluffy paddy soils
Surface crusting
Slow Permeable Soil
High clay content
Low Infiltration Rate – 6 cm/day
High Surface Runoff
Impeded DrainageLow nutrient availability due to fixation in clay lattice
Slow Permeable Soil 739 sq.km in Coimbatore, 526 sq.km in Dharmapuri 1243 sq.km in Trichy and 420 sq.km in Salem district
Apply organic manures 10 to 15 t/ha to improve soil physical properties
Form Ridges and Furrows to Provide aeration to roots and provide adequate drainage
Excessive Permeable Soil
High sand > 70 %
Low water and nutrient retention capacity
Weak aggregate structure due to low OM and finer fractions
6,519 sq.km in Coimbatore, 3,774 sq.km in Dharmapuri; 2,800 sq.km in Trichi, 1,837 sq.km in Madurai, 1,845 sq.km in Salem and 524 sq.km in North Arcot Districts.
Excessive Permeable Soil
Plough the soil uniformly 24 hours after rains or irrigation
The soil should be rolled 10 times with 400 kg stone roller of 1 met long (or) an empty tar drum filled with 400 kg sand
Sub soil hard panOccur in red soils – 8 m ha in T N
illuviation of clay to the sub soil horizons coupled with cementing action of oxides of iron, Aluminium and calcium carbonate
High BD – 1.8 g/cc
low infiltration, WHC, available water and movement of air and nutrients
1,320 sq.km in Coimbatore, 2,450 sq.km in Madurai and 1,448 sq.km in North Arcot districts.
Sub soil hard panAdvantages of chisel ploughingReduces the BD by 0.2 to 0.4 mg. m-3.
The hydraulic conductivity was almost doubled in sub soil
Conserves 30-40% more soil moisture.
Roots proliferation is improved by 40-45%.
Nutrient mobility especially N & K increased by 20-30% and 30-40%
Shallow Soils:
Parent rock immediately below the soil surface at about of 15-20 cm depth.
This restricts the root elongation and spreading. 209 sq.km and 384 sq.km in Salem and North arcot districts .
Fluffy Soils:
Continuous submergence and intense cultivation – Soil structure destroyed
Low BD, Mechanical Strength, poor anchorage to plants Situation further aggravated by stubble incorporation
Fluffy Soils:
After the harvest of Rice, when the soil is under semi-dry condition, compact the field by passing 400 kg stone roller (or) an empty tar drum filled with 400 kg of sand 8 times.
Surface CrustingFound in red soils of Trichy, Pudukottai, Ramnad and Tirunelveli.
Colloidal oxides of iron and aluminium in alfisols bind the soil particles under wet regimes. On drying it forms a hard mass on the surface.
It prevents germination of seeds; inhibits root growth poor infiltration, accelerates surface runoff, poor aeration, affects nodule formation in leguminous crops.
Surface Crusting
Plough the soil at optimum moisture and apply lime 2 t/ha and plough again
Apply FYM or CPC 10 t/ha to improve soil physical properties
Scraping surface soil by tooth harrow will be useful.
Sprinkling water at periodical intervals may be done wherever possible.