• Pearl millet is susceptible to waterlogging during seedling stage while it can tolerate at later stages.
• Yield of cereals is depressed if the soil is waterlogged during panicle development.
• Pulses are susceptible to water logging at initial period of reproductive stage.
• Temperature is the important climatic factor influencing the extent of damage due to excess moisture.
• Injury due to waterlogging is severe under warm weather conditions.
• Flooding is more harmful on sunny days than on cloudy days.
• Flopping or wilting of tobacco takes place only when sunshine occurs after prolonged dry spell.
• Under water logged conditions proportion of aerenchymatous tissue in the root system increases.
• Ethanol production increases and activity of alcohol dehydrogenase increases in roots of waterlogged plants.
• Under waterlogged conditions permeability of roots decreases due to shortage of oxygen resulting in decreased water uptake and wilting symptoms appear even though soil contains excess water.
• Permeability of roots for nutrients also reduced under waterlogged conditions.
• Adverse effects of waterlogging can be reduced to some extent by supplying nitrogenous fertilizers.
• Waterlogging can be avoided by providing drainage.
• Agricultural drainage is the provision of a suitable system for the removal of excessive irrigation or rain water from the land surface so as to provide suitable soil conditions for better plant growth.
• Rate of drainage is amount (expressed in depth) of water drained off from a given area in 24 hours.
• Rate of drainage also called as drainage coefficient or drainage design rate.
• Rate of drainage expressed in terms of flow rate per unit area (m3/ha/day).
• Runoff coefficient is the amount of runoff expressed as a percentage of the total rainfall in a given area.
• Drainage improves soil aeration and increases soil temperature.
• Surface drainage is the simplest and most common method in India.
• Provision of surface drainage is cheap.
• Disadvantages of surface drainage
1) Land is wasted for open drains
2) Drains cause obstruction to field preparation and intercultivation
3) Drains get silted and periodical desilting is necessary
4) Weed growth in the drains is heavy
5) Open drains are damaged by rodents and farm animals
• Subsurface drainage requires less maintenance, high initial investment.
• Failure of the sub surface drainage system is difficult to detect.
• Subsurface drainage system is ineffective in soils with low permeability.
• Open trenches, tile drains, mole drains, perforated drains are used in subsurface drainage.
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