Drainage requirement in rice EndNext

 Rice is the most important food crop of the world.  Rice is a semi-aquatic plant and hence survives better under water logged condition compared to other crops.  Drainage is the artificial removal of water in excess of the quantity required for the crop.  Drainage includes removal of excess water of both surface and subsurface in the root zone of crops.  Water logging occurs due to excess rainfall, floods, tidal waves etc. and water loss happens due to runoff, deep percolation, evapo-transpiration etc. PreviousEndNext INTRODUCTION

 When the former one exceeds the later, drainage requirement is realized.  There are many causes are realized due to water logging in rice fields.  Removal of excess water through drainage improves the soil condition and in turn growth and yield of rice. PreviousEndNext  Water logging occurs due to excessive rainfall, floods, rise of ground water level, tidal water and even excessive irrigation.  Though rice is grown under submerged conditions, it responds well to adequate drainage.  Due to continuous growing of rice under submerged condition, the soils develop ill or poor drained conditions. WATER LOGGING

 The natural processes like surface runoff, deep percolation and evapo-transpiration are not adequate enough to drain such waterlogged areas within reasonable period without affecting the crop yields. PreviousEndNext Causes of water logging :  At a number of places, the problem of excess water is also associated with the salinity and alkalinity problems, which further aggravate the situation.  Continued stagnation of water often leads to accumulation of toxic bio-chemical substances and silt deposition.

 Rice grown in ill-drained soil is subject to toxic effect of reduced products as sulphides and methane.  Further, the problem is more acute when organic matter content of the soil is high.  The benefit of drainage is attributed to better aeration and / or removal of toxic substances such as high concentration of ferric ions and hydrogen sulphide. PreviousEndNext

 Drainage is necessary in heavy clay soils. Drainage in sandy soils leads to leaching of nutrients.  Drainage can be through vertical drainage or surface drainage.  There is no difference in beneficial effect between them since they serve the same purpose.  Drainage exerts beneficial effects on soils with abundant production of toxic substances and also in fields where large quantity of green manure have been applied.  The extent of drainage and type of drainage system to be adopted will depend on several factors relating to soil, crop, weather and the hydrological characteristics of an area. PreviousEndNext DRAINAGE

 Moreover, certain stages of growth like early flowering have been reported to be more susceptible to water logged conditions than other stages of crop growth (CRRI, 1980). Excess water draining form rice fields PreviousEndNext

 The drainage should be synchronized with the period just following tillering and flowering.  Even 4 days complete submergence at flowering was more detrimental than 8 days of submergence at seedling establishment and 12 days of submergence during the late vegetative phase.  The drainage period could last from 3-7 days depending upon the type of soil.  In case of sandy soils, drainage is about 3 days while in the case of clayey soils it is about 5 to 7 days. PreviousEndNext

 A study on depth and frequency of drainage conducted at Cuttack (CRRI, 1968) revealed that lowering the water table up to cm below the surface gave the highest yield.  The design of drainage system will also vary with the situation (Sarkar, 1980).  However, surface drainage system would be adequate for rice fields as the water table is not required to be lowered too deep. PreviousEndNext

Rice is a semi-aquatic plant and hence survives better under water logged condition than other crops. Though rice is grown under submerged conditions, it responds well to adequate drainage. Continued stagnation of water often leads to accumulation of toxic bio-chemical substances and silt deposition. Rice grown in ill-drained soil is subject to toxic effect of reduced products as sulphides and methane Previous EndNext Summary

Drainage is necessary in heavy clayey soils. Drainage in sandy soils leads to leaching of nutrients. The extent of drainage and type of drainage system to be adopted will depend on several factors. The drainage should be synchronized with tillering and flowering periods of rice. Surface drainage system would be adequate for rice fields as the deep water table is not required to rice. PreviousEndNext

1.Rice is a semi-aquatic plant and survives well under water logged condition (True/False). 2.Rice will not respond to adequate drainage (True/False). 3.Rice grown in poor drained soil produces toxic substances like sulphides and methane (True/False). 4.Drainage is more necessary in heavy clayey soils than sandy soils for rice (True/False). 5.The drainage is much needed during tillering and flowering stages of rice (True/False). 6.Rice field needs sub surface rather surface drainage system (True/False). PreviousEndNext ASSESSMENT

: CRRI, Annual Report. Central Rice Research Institute, Cuttack, India. CRRI, Rice Research in India – An overview. Central Rice Research Institute, Cuttack, India. Rajendra Prasad, A Text book of Rcice Agronomy. Jain Brothers, New Delhi. Sankara Reddi, G.H. and T. Yellamanda Reddy, Efficient Use of Irrigation Water. Kalyani Publishers, Ludhiana. Sarkar, T.K Drainage System Designs. In: Design Manual. Water Technology Centre. Indian Agricultural Research Institute, New Delhi. PreviousEnd REFERENCES