1) Adequate Water Supply (Normal / Ample Water Availability)

Objective: Maximize yield potential by meeting full crop water requirement (ETc).

Strategies:

• Optimum irrigation scheduling – based on soil moisture depletion (e.g., IW/CPE ratio).
• Critical growth stage approach – irrigation given at most sensitive stages (e.g., CRI in wheat, flowering in maize).
• Proper method selection – border strip (wheat, barley), basin (orchards), furrow (cotton, maize, sugarcane).
• Avoid over-irrigation – prevents waterlogging, salinity.
• Use of water-saving methods – AWD in rice, SRI in rice.

2) Limited Water Supply (Scarcity / Deficit Conditions)

Objective: Optimize use of scarce water, ensure survival & reasonable yield.

Strategies:

• Critical stage irrigation – water applied only at growth stages most sensitive to stress.
  • Wheat → Crown Root Initiation (CRI), flowering, grain filling.
  • Maize → tasseling–silking.
  • Groundnut → pegging, pod development.
• Deficit irrigation – water supplied < full requirement but strategically timed.
• Regulated Deficit Irrigation (RDI) – mild stress induced during less-sensitive stages (e.g., vegetative stage in grapes).
• Mulching – reduces evaporation, conserves soil moisture.
• Conjunctive use – blending canal + groundwater.
• Crop planning – short-duration, drought-tolerant crops/varieties.
• Micro-irrigation (drip/sprinkler) – saves 30–60% water.

3) Uncertain / Irregular Water Supply (Rainfed, Erratic Rainfall, or Canal Water Supply Not Assured)

Objective: Minimize risk of crop failure and maximize rainwater use.

Strategies:

• Rainwater harvesting – farm ponds, check dams, percolation tanks for supplemental irrigation.
• In-situ moisture conservation – contour farming, ridges and furrows, mulching, conservation tillage.
• Life-saving irrigation – one or two irrigations at crucial stages using harvested water.
• Crop substitution – shift from high water requiring (paddy, sugarcane) to low water requiring (millets, pulses).
• Intercropping systems – pigeonpea + sorghum, maize + cowpea for risk minimization.
• Watershed management – integrated management of soil and water resources.

4) Excess Water Supply (High Rainfall / Waterlogged Areas / Canal Command Problems)

Objective: Prevent waterlogging, salinity, and crop damage.

Strategies:

• Surface drainage – open ditches, ridges and furrows.
• Sub-surface drainage – tile drains, perforated pipes.
• Bio-drainage – planting deep-rooted trees (eucalyptus, casuarina).
• Raised-bed or ridge planting – maize, soybean, cotton in canal commands.
• Crop planning – water-tolerant crops (rice, jute, sugarcane).
• Proper canal management – lining, rotational supply, PIM (Water Users’ Associations).

5) Use of Poor-Quality Water (Saline / Sodic / Industrial Effluents)

Objective: Safely use marginal-quality water without affecting productivity.

Strategies:

• Blending / cyclic use – mix with good-quality water.
• Soil amendments – gypsum for sodic water, organic matter for structure improvement.
• Leaching requirement – apply extra water to flush salts below root zone.
• Selection of tolerant crops/varieties – barley, cotton, sorghum (saline tolerant).
• Conjunctive use – saline groundwater + canal water.

Summary Table – Irrigation Strategies

Facts on Irrigation Strategies Under Different Water Availability Situations

General

• Total irrigation efficiency in India:
  • Surface irrigation: 30–40%
  • Sprinkler: 60–70%
  • Drip: 80–90%
• About 80–85% of total freshwater in India is used for agriculture.
• Micro-irrigation can save 30–60% water and increase yield by 20–40%.

Adequate Water Supply

• Optimum irrigation scheduling can improve Water Use Efficiency (WUE) by 15–25%.
• AWD (Alternate Wetting and Drying) in rice saves 30–40% water without yield loss.
• SRI (System of Rice Intensification) reduces water requirement by 25–30%.

Limited Water Supply

• Critical irrigation stages:
  • Wheat → CRI (20–25 DAS), flowering, grain filling.
  • Maize → tasseling–silking.
  • Groundnut → pegging & pod filling.
• Irrigation at CRI in wheat can increase yield by 40–60% compared to no irrigation.
• Mulching reduces evaporation losses by 20–25%.
• Drip irrigation in sugarcane saves ~45% water with ~25% yield increase.

Uncertain / Rainfed Situations

• 68% of net sown area in India is rainfed.
• Watershed management can increase cropping intensity by 30–50%.
• Supplemental irrigation in rainfed crops increases yields by 25–50%.
• Farm ponds store 1000–5000 m³ water for life-saving irrigation.

Excess Water / Waterlogging

• Waterlogging + salinity affect ~8.4 million ha in canal commands.
• Subsurface drainage can reduce water table by 1–2 m and reclaim productivity.
• Bio-drainage (eucalyptus) can transpire 50–60 liters/day/tree, helping reduce waterlogging.

Poor Quality Water Use

• Saline water threshold (EC): most crops tolerate up to 2 dS/m, tolerant crops up to 6–10 dS/m.
• Sodic water: RSC > 2.5 meq/L is unsafe without gypsum.
• Gypsum requirement (GR) is calculated for neutralizing sodicity in irrigation water.
• Blending saline water with canal water reduces EC by 30–40%, making it usable.