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Crop Production (Unit 6)
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ASRB NET / SRF / Ph.D. Agronomy
Management of Water Resources for Agricultural Production

India receives about 4000 billion m³ of rainfall annually, but only ~1123 billion m³ is utilizable due to uneven distribution in time and space. Agriculture consumes about 80–85% of total water resources. Efficient management of rainwater, canal water, and groundwater is crucial for sustainable food security.

 

1) Rainwater Management

Rainwater is the primary and renewable source of water. Nearly 68% of cultivated area in India is rainfed. Rainwater management aims to conserve, store, and utilize rainfall effectively.

(a) In-situ Rainwater Conservation

  • Contour bunding and contour farming – reduce runoff, increase infiltration.
  • Terracing in hilly areas – prevents soil erosion.
  • Mulching (organic residues, plastic films) – reduces evaporation losses.
  • Tied ridges and furrows – store water in small catchments.
  • Conservation tillage / zero tillage – maintains soil cover, reduces evaporation.

(b) Rainwater Harvesting & Storage

  • Farm ponds – small excavations for harvesting field runoff; used for supplemental irrigation, fish culture.
  • Check dams, stop dams, nala bunds – check flow of water in streams and increase groundwater recharge.
  • Percolation tanks – enhance recharge of aquifers.
  • Roof water harvesting – urban/rural homesteads.

(c) Supplemental Irrigation in Rainfed Agriculture

  • Even 1–2 irrigations at critical crop stages (flowering, grain filling) can stabilize yield.
  • Example: 1 irrigation at pod initiation in pulses increases yield by 25–40%.
  • Crops: sorghum, pearl millet, pulses, oilseeds in semi-arid zones.

(d) Watershed Management Approach

  • Integrated watershed management combines soil conservation, rainwater harvesting, afforestation, and farming system diversification.
  • Example projects: Sukhomajri watershed, Ralegan Siddhi (Maharashtra).

 

2) Canal Water Management

Canals distribute water from rivers or reservoirs across command areas. Canal irrigation covers ~17% of net irrigated area in India, but suffers from low efficiency (30–40%).

(a) Efficient Conveyance and Distribution

  • Lining of main canals, distributaries, field channels – reduces seepage (saves 15–20% water).
  • Warabandi system – rotational water distribution ensuring equitable and fixed turns to farmers.
  • Water measuring devices (Parshall flumes, cut-throat flumes) – regulate and monitor water delivery.

(b) On-Farm Water Management

  • Field leveling (laser leveling) – reduces uneven distribution, saves 20–25% water.
  • Irrigation scheduling – based on crop water requirement (ETc) and soil moisture.
  • Methods of irrigation
    • Border strip irrigation (wheat, barley).
    • Furrow irrigation (cotton, maize, sugarcane).
    • Basin irrigation (orchards).
    • Surge irrigation (intermittent water flow).

(c) Problems in Canal Command Areas

  • Waterlogging – due to seepage and over-irrigation.
  • Soil salinity/alkalinity – due to rise of saline water table.
  • Inequity – head-reach farmers get more water than tail-end farmers.

(d) Solutions

  • Subsurface drainage – pipes or open drains.
  • Bio-drainage – planting deep-rooted trees (eucalyptus, casuarina).
  • Conjunctive use – mixing canal water with groundwater to avoid waterlogging and salinity.
  • Participatory irrigation management (PIM) – Water Users’ Associations (WUAs) for equitable distribution.

 

3. Groundwater Management

Groundwater is the largest source of irrigation in India (~60% of irrigated area), but faces threats of over-extraction and quality deterioration.

(a) Efficient Extraction and Use

  • Dug wells and tube wells – widely used for localized irrigation.
  • Lift irrigation schemes – lift water from rivers, reservoirs.
  • Water-saving methods – drip irrigation (saves 40–60%), sprinkler irrigation (saves 30–40%).
  • Deficit irrigation and Regulated Deficit Irrigation (RDI) – less than full requirement but timely.

(b) Groundwater Recharge Techniques

  • Percolation tanks, recharge wells, injection wells.
  • Check dams, farm ponds, nala bunds.
  • Aquifer recharge through canal seepage interception.
  • Recharge trenches in urban areas.

(c) Groundwater Quality Management

  • Saline water use – possible with blending, cyclic use, or by growing salt-tolerant crops (barley, sorghum, cotton).
  • Sodic groundwater – ameliorated using gypsum or organic amendments.
  • Conjunctive use – combining poor-quality groundwater with canal water.

 

4. Integrated Water Resource Management (IWRM)

IWRM promotes holistic utilization of rain, canal, and groundwater for sustainability.

  • Crop planning – select crops according to available water (e.g., paddy in canal commands, pulses in rainfed).
  • Conjunctive use – balancing canal and groundwater to avoid overuse of either.
  • Watershed approach – integrates soil, water, vegetation, and livestock.
  • Micro-irrigation + fertigation – for high-value crops (fruits, vegetables, flowers).
  • Precision irrigation technologies – sensor-based scheduling, automation.

 

6) Advanced Water-Saving Concepts

  • System of Rice Intensification (SRI) – alternate wetting & drying in rice (saves 30–40% water).
  • Alternate Wetting and Drying (AWD) in rice – water saved without yield loss.
  • Laser land leveling – uniform field slope saves ~25% water.
  • Deficit irrigation strategies – maximize WUE under limited water.
  • Use of Remote Sensing & GIS – monitoring groundwater, evapotranspiration, crop water stress.

 

Key Facts on Water Resource Management in Agriculture

General Water Resources

  • Total annual rainfall in India: ~4000 billion m³.
  • Utilizable water resources: ~1123 billion m³ (690 surface + 433 groundwater).
  • Agriculture consumes ~80–85% of total water resources.
  • Irrigation efficiency in India:
    • Surface irrigation: 30–40%.
    • Sprinkler irrigation: ~60–70%.
    • Drip irrigation: ~80–90%.

 

Rainwater

  • 68% of India’s net sown area is rainfed.
  • Contribution of rainfed areas: 44% of food grains, 75% of pulses, 90% of coarse cereals, 70% of oilseeds.
  • Supplemental irrigation with harvested rainwater can increase crop yield by 25–50% in pulses and oilseeds.
  • Watershed projects (e.g., Sukhomajri, Ralegan Siddhi) demonstrated 2–3 times increase in productivity.

 

Canal Water

  • Canal irrigation covers ~17% of net irrigated area.
  • Average conveyance efficiency of canals: 35–40% (due to seepage, evaporation, theft).
  • Warabandi system (rotation method) increases equity and saves water by 15–20%.
  • Waterlogging and salinity affect ~8.4 million ha in canal command areas.
  • Laser land leveling in canal commands saves 20–25% water and increases yield by 10–15%.

 

Groundwater

  • Groundwater contributes ~60% of total irrigation.
  • About 30% of blocks in India are over-exploited or critical.
  • Drip irrigation in horticulture saves 40–60% water and increases yield by 20–30%.
  • Sprinkler irrigation reduces water use in wheat and mustard by ~30%.
  • Groundwater recharge structures can increase water table by 1–3 m locally.
  • Saline/sodic groundwater affects ~6 million ha area in India.

 

Integrated Water Resource Management (IWRM) Facts

  • Micro-irrigation potential in India: ~69 million ha; current coverage only ~14 million ha (2023).
  • Alternate Wetting and Drying (AWD) in rice saves 30–40% irrigation water.
  • System of Rice Intensification (SRI) reduces water use by 25–30% while maintaining yield.
  • Watershed management improves cropping intensity by 30–50% in drylands.
  • Conjunctive use of canal and groundwater reduces salinity and waterlogging by 20–25%.

 

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