The irrigation method in which water is delivered slowly and directly to the base of each plant through narrow tubes or pipes is called:

Drip irrigation (also called trickle irrigation or micro-irrigation) delivers water drop by drop, directly to the root zone of each plant, through a network of pipes, tubes and small outlets called emitters or drippers.

How drip irrigation works:

• Water from a source (such as a well, tank or canal) is filtered to remove particles that could block the emitters.
• It is carried through a main pipe and sub-main pipes to lateral tubes laid along the rows of plants.
• Emitters on the lateral tubes release water slowly at the base of each plant.
• Fertilisers dissolved in the water can also be supplied directly to the roots, a method called fertigation.

Advantages:

• It saves a large amount of water, often 30 to 70 per cent compared with flood irrigation, because water is not lost through runoff, deep percolation or evaporation from a wide wet surface.
• It increases crop yields and quality, since plants get a steady supply of water and nutrients.
• It reduces weed growth, because only the area near the plants is wet.
• It saves labour, energy and fertiliser.
• It can be used on uneven land, sandy soils and slopes, and with saline water to some extent.

Disadvantages:

• High initial cost.
• Emitters can get clogged if the water is not properly filtered.

Suitable crops:

It is especially useful for widely spaced crops, such as fruit trees (grapes, banana, pomegranate, mango), vegetables, sugarcane and cotton.

Promotion in India:

• Micro-irrigation (drip and sprinkler) is promoted under the "Per Drop More Crop" component of the Pradhan Mantri Krishi Sinchayee Yojana (PMKSY), with subsidies for farmers.
• Maharashtra, Andhra Pradesh, Karnataka, Gujarat and Tamil Nadu have the largest areas under drip irrigation.
• Israel is known worldwide as a pioneer of modern drip irrigation, developed by Simcha Blass in the 1960s.

Why not the other options?

• ✗Sprinkler irrigation sprays water over the crop like rain.
• ✗Basin (flood) irrigation floods the whole field and wastes much water.
• ✗Furrow irrigation sends water along channels between rows.