Rice

Water Management

Introduction Principles Losses Of Water Irrigation Schedule Water management (Nursery) Main field

Introduction

  • Excess or limited or no water leads to poor growth and reduction in yield.
  • Every crop plant tries to survive under extreme drought conditions but never survives for atleast 1-2 days under excess moisture situation
  • Rice a semi-aquatic plant
  • Submergence helps in – suppressing weed growth, more availability nutrients
  • Daily consumptive use of rice is 6-10 mm.
  • Total water requirement for rice is 1240mm
  • 5000 litres of water is required to produce 1 kg of rice
  • Rice accounted for 33% of gross irrigated area
  • Rice consuming 66% of total available irrigation water

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Principles

  • Saline and brackish water is not good for irrigation
  • Application of FYM or incorporation of green manures reduce adverse effects of excess salts
  • Application of FYM or compost or green manures or composted coir pith increase water holding capacity of light textured soils and thus saves water
  • Field management for higher water use efficiency through puddling. Impermeable layer reduces deep percolation losses. Perfect levelling maintains uniform depth of water throughout field.

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Losses of water in rice fields

  • Evaporation (E) – 180-300mm unavoidable
  • Transpiration (T) – 200-500mm unavoidable
  • Average evopotranspiration (ED) is 7mm/day/South-West monsoon and 10mm/day/North-East monsoon.
  • Seepage and percolation – 200-500m. It may be reduced to some extent by thorough puddling and perfect levelling
  • Application of phosphatic fertilizers increases transpiration
  • Application of FYM or compost or green manures reduce evaporation, percolation and seepage
  • Evaporation losses can be minimized by 50% when the soil is kept at saturation. Needless to say such a shallow water application practice requires perfectly levelled land.
  • Addition of clay or tank silt (to light textured soils only) @ 150m3/ha reduces percolation loss by 20-25%
  • Addition of bentonite @ 7000kg/ha
  • Seepage varies according to topography, depth of ground water table and farming practice
  • Seepage facilitates removal of toxic salts and supply of oxygen to roots
  • Disadvantages with seepage are: wastage of water and nutrient leaching.

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Irrigation Schedule

Short duration variety
Medium duration variety
Long duration variety
Days
No.of irrigation
Water level (cm)
Days
No.of irrigation
Water level (cm)
Days
No.of irrigation
Water level (cm)
1-25
5-7
2-3
1-30
5-7
2-3
1-35
6-8
2-3
25
-
Thin film of water
30
-
Thin film of water
35
-
Thin film of water
28
-
Life irrigation
33
-
Life irrigation
38
-
Life irrigation
29-50
6
2-5
34-65
6-8
2-5
39-90 or 95
12-15
2-5
51-70
5-6
2-5
66-95
8-10
2-5
96-125
7-9
2-5
71-105
5-6
2-5
96-125
6-8
2-5
126-150
5-6
2-5

Note:

Stop irrigation 10 days before harvest Number of irrigation may be decided depending upon the receipt of rain and available moisture content.

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Water management (Nursery)

  • Water should be drained next day after sowing.
  • Allow enough water to saturate the soil from 3rd to 5th day
  • Protect the seeds from tilting due to rain.
  • Maintain wet condition to avoid cracks and development of long roots
  • From 5th day onwards, raise water level from 1.5cm to 2.5cm according to the height of the seedling.

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Main field

  • Summer ploughing minimises water requirement for land preparation
  • Maintain thin film of water at the time of planting (2cm)
  • Life irrigation should be given on 3rd day
  • Upto 7 days, 2cm water level should be maintained
  • Gradually raise water level to a depth of 5 cm upto maturity
  • Critical stages are primordial initiation, booting, heading, flowering. Water level should be maintained to get good yield.
  • Moisture stress during rooting and tillering stage cause poor root growth leading to poor crop establishment and low yield.
  • Stop irrigation 10-15 days before harvest
  • Spray Cycogel @ 1000ppm (1ml of commercial product in one litre of water) under water deficit situations to mitigate ill effects.
  • Split application of potassium 50% at basal and 25% each at tillering and panicle initiation stage along with Azospirillum (seed inoculation, seedling dipping or soil application) alleviates harmful effects of the soil moisture deficiency.
  • Foliar application of kaolin 3% (30 g/lit) or potassium chloride 1% (10 g/lit) is made to overcome moisture stress at different physiological stages of rice.
  • Field to field irrigation is to be avoided. Small bunds at convenient distance parallel to main bunds will help in avoiding leakage due to flood irrigation.

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Tamilnadu

Rice

Rice Management