Methods of Irrigation

Irrigation is crucial in agriculture, especially for crops that require consistent water supply for optimal growth. There are several methods of irrigation, each with its own techniques, advantages, and applications. The selection of an irrigation method depends on factors like water availability, crop type, land slope, and cost considerations. Below is a detailed breakdown of various methods of irrigation used for crops:

a) Surface or Gravity Irrigation

Surface irrigation is one of the oldest and simplest methods where water is distributed across the soil surface and allowed to flow over the land by gravity.

Types of Surface Irrigation:

• Flood Irrigation:
  • In flood irrigation, water is applied over the entire field and allowed to cover the soil surface. It can be either controlled or uncontrolled.
  • Crops Suitable: Paddy, rice, sugarcane, and other crops grown in low-lying areas.
  • Advantages: Simple, low initial cost.
  • Disadvantages: High water wastage, inefficient for crops sensitive to waterlogging.

• Border Irrigation:
  • The land is divided into long, narrow strips, and water is applied to the upper end of these strips. The water flows down the strip, covering the soil.
  • Crops Suitable: Vegetables, row crops, and wheat.
  • Advantages: Less water wastage compared to flood irrigation, efficient for well-drained soils.
  • Disadvantages: Requires level land, not ideal for uneven terrain.

• Furrow Irrigation:
  • In this method, small furrows (shallow channels) are dug between crop rows. Water is allowed to flow into these furrows.
  • Crops Suitable: Row crops like corn, cotton, beans, and potato.
  • Advantages: Reduces evaporation, less water wastage than flood irrigation, suitable for large field crops.
  • Disadvantages: Not suitable for very sandy or clay soils; requires flat land.

• Check Basin Irrigation:
  • The field is divided into small basins surrounded by bunds (small embankments). Water is applied within each basin to irrigate plants.
  • Crops Suitable: Orchards, vegetables, and trees like apple and mango.
  • Advantages: Efficient for tree crops, reduces surface runoff, and prevents waterlogging.
  • Disadvantages: Requires considerable labor for basin construction.

• Ring Irrigation:
  • Circular embankments (rings) are formed around individual plants, and water is applied to fill the ring and irrigate the plants.
  • Crops Suitable: Fruit crops, especially trees.
  • Advantages: Water is confined to the root zone, reducing wastage.
  • Disadvantages: Requires careful management and monitoring.

b) Subsurface Irrigation

Subsurface irrigation involves applying water beneath the soil surface through a network of pipes or other water distribution systems.

Types of Subsurface Irrigation:

• Tile Drainage System:
  • Water is applied through underground pipes or tiles buried beneath the soil surface. The water moves upward through capillary action to reach the root zone.
  • Crops Suitable: Rice, sugarcane, horticultural crops.
  • Advantages: Reduces evaporation, prevents surface water loss, ideal for drought-prone areas.
  • Disadvantages: High initial setup cost, maintenance-intensive.

• Drip Irrigation (Subsurface Type):
  • Water is applied directly to the root zone via a network of pipes and emitters located below or on the soil surface.
  • Crops Suitable: Orchards, vine crops (grapes, tomatoes), vegetables, and greenhouse crops.
  • Advantages: Very water-efficient, reduces weed growth, ensures precise water distribution.
  • Disadvantages: High cost of installation and maintenance, requires filtration systems.

c) Pressurized Irrigation (Micro Irrigation)

Pressurized irrigation uses pressurized water to distribute it uniformly to the crops. The most common types are drip irrigation and sprinkler irrigation.

Types of Pressurized Irrigation:

• Drip Irrigation:
  • Water is applied drop by drop directly to the root zone using a network of pipes, valves, and emitters.
  • Crops Suitable: Vegetables (tomatoes, peppers), fruit crops (citrus, grapes), and field crops (maize, cotton).
  • Advantages: Extremely efficient, reduces water wastage, promotes deep root growth, can be used for fertigation.
  • Disadvantages: High initial setup cost, clogging of emitters, maintenance intensive.

• Sprinkler Irrigation:
  • Water is sprayed over the crops in the form of droplets, simulating natural rainfall. Sprinklers are placed above or near the crops.
  • Crops Suitable: Row crops like wheat, maize, cotton, as well as vegetables, and flowers.
  • Advantages: Suitable for irregular terrain, water distribution is uniform, adaptable for large fields.
  • Disadvantages: High installation cost, requires power to operate, water loss due to wind and evaporation.

• Rain Gun Irrigation:
  • A type of sprinkler irrigation, rain guns use large nozzles that spray a wider area, often covering large fields.
  • Crops Suitable: Large-scale crops such as cereals, pulses, and vegetables.
  • Advantages: Covers large areas, can be used for high-value crops, highly flexible.
  • Disadvantages: Expensive setup, needs frequent maintenance, may cause waterlogging in heavy rainfall.

• Center Pivot Irrigation:
  • A rotating sprinkler system that irrigates large circular areas, typically using pipes mounted on wheeled towers.
  • Crops Suitable: Crops in large fields, such as maize, wheat, and cotton.
  • Advantages: Suitable for large, flat fields, efficient water usage.
  • Disadvantages: Expensive setup, limited to large-scale farming.

d) Other Methods of Irrigation

• Capillary Irrigation:
  • Water is supplied to the plants through capillary action. Often used in pots and small containers, it helps maintain moisture levels in the soil.
  • Crops Suitable: Indoor plants, small container crops.
  • Advantages: Simple to use for small-scale applications, low cost.
  • Disadvantages: Not feasible for large-scale field crops.

• Pitcher Pot Irrigation:
  • Porous clay pots are placed near the roots of plants. Water gradually seeps out of the pot and into the soil.
  • Crops Suitable: Trees and shrubs, especially in arid regions.
  • Advantages: Efficient water usage, reduces evaporation.
  • Disadvantages: Labor-intensive, high cost of pots.

Comparison of Irrigation Methods for Crops