Water Management

Introduction & Principles Water requirement stage wise Critical stages of water requirement Losses of water in rice fields Water quality and critical values

Introduction & Principles

  • Every plant requires moisture to maintain cell turgidity - helps in more carbon dioxide diffusion leads to high photosynthetic activity.
  • This is one of the reasons why an irrigated crop with give higher yields over an un-irrigated crop.
  • Moisture in the plant maintains the optimum plant body temperature by circulation of water through plant system and thus transpiration is a necessary evil.

Principles of water management

  • Excess/limited/no water leads reduction in yield.
  • Chilli crop is very sensitive to excess water but to some extent it can tolerate drought.
  • Majority of crops will give more than double the yield under irrigation over rainfed crop.
  • Adoption of proper water management practices leads not only saving valuable water but also yield more per unit quantity or water supplied (WUE).
  • Heavy soils or in heavy rainfall areas proper drainage should be provided to withdraw excess water.
  • Irrigation water quality is very important in order to maintain the soil health, higher yield, even and quality of produce, since quality is very important parameter for certain commercial crops like chilli.

  • Under limited water availability conditions provide irrigation only at important critical stages of crop so that the yield reduction is not substantial and the water use efficiency is very high.
  • While irrigating chilli crop in heavy soil care should be exercised that they should not be water stagnation even for few hours


Water requirement - Stage wise

  • Nursery ( 45 days) : 200 mm
  • Transplanting to flowering : 200 mm
  • Flowering to first pickup : 250 mm
  • Fruit development and maturing: 250 mm (Dry chilli)
  • 400 mm (green chilli)
  • Total Water requirement : 900 mm (Dry chilli)
  • 1050 mm (green chilli)


  • Number of irrigations, interval between two successive irrigations depends on type of soils, age of crop and climatic conditions
  • Light soils : 7-10 days interval
  • Heavy soils : 10-15 days interval
  • Summer : 5-6 days interval
  • After every harvesting of chilli one irrigation should be provided (as per the moisture regime of soils)
  • Irrigation should be provided at 40-60% depletion of available soil moisture.


Critical stages of water requirement

Flowering and fruit development in chilli are the most critical stages of water.

Excess irrigation at these stages causes;

  • Reduction in flowering and yield.
  • Incidence of fungal diseases.
  • Reduction in capture of nutrients

Less irrigation than required causes

  • Flower and fruit drop
  • Less branching.
  • After prolonged drought if irrigation is provided at flowering and fruiting stage, lot of flower and fruit drop will be seen.


Losses of water in rice fields

  • When a crop is irrigated the water losses may be through deep percolation (when excess irrigation than required) evaporation from soil body till the crop completely develops its canopy and transpiration losses.
  • To reduce deep percolation losses for irrigable - dry crops like chill quantity irrigation water to be supplied should be quantified as per the texture of soil, rooting depth, season of crop growth etc.
  • Out of total water supplied about 99 percent of water utilised by the crop only to meet the evapo-transpiration demand and only 1% of moisture used for different metabolic activities.
  • Drastic reduction of evaporation and transpiration by any means may reduce the yields.
  • Hence, the losses of water through deep percolation can only be reduced by better water management practices.


Water quality and critical values

Types of problems and critical values

Potential problem
No probelm
Slight to moderate problem
Severe problem
No units
<6.5: >8.5
Salanity Ecw
Ds/m=m Mol/cm
> 2.6
> 2000
Specific in toxicity
No units
> 9
> 10

* TDS = Total Dissolved Salts

  • For each 1ppm element in the water, the input is 1000 mm equivalent to 10 kg/ha.
  • If pH is out of range (6.5-8.4) but with low salinity (<0.2 Ds/m) then there is likely no problem as the water has very low buffering. However, additional checks should be pursued for possible nutrient imbalance.
  • Abnormal pH damage the equipment as the water is corrosive.
  • High bicarbonate levels in irrigation water can cause Zn deficiency.
  • Large masses of silt must be avoided for heavy soils.
  • High sodium water cause de-flocculation of soil particles leads to increase stickyness and compactness and decrease permeability.
  • Specific conductivity of ideal water : (K x 106) < 7500
  • Boron < 1ppm
  • S.A.R Index < 1
  • Ecw = Irrigation water salinity
  • Ece = Soil salinity a measure on a saturation extract
  • SAR = Sodium/(Square root (Calcium + Magnesium/2); Sodium, Calcium and Magnesium in me/l.


Andhra Pradesh