Drip irrigation

Also called: Trickle irrigation · Topic: Water Resources of India: Availability, Use and Conservation · NCERT: Class 7, Ch 1 "The Story of Indian Farming"

Meaning

Drip irrigation (also called trickle irrigation) is a type of micro-irrigation that sends water slowly, drop by drop, through pipes and small emitters (tiny outlets) straight to the roots of each plant. It saves about 40-70% of water and fertiliser. Agriculture uses most of India's water and groundwater is running low, so drip irrigation is one of the main ways to get "more crop per drop".

Explanation

How it works

• Cause: flood irrigation wastes water.
• In flood irrigation, water spreads over the whole field.
• Much of it evaporates or sinks below the roots, so little of it reaches the plant.

• In canal areas this also causes waterlogging (the soil stays soaked with water) and salinity (salt builds up in the soil).

• Process: water goes only where the plant needs it.

• A main pipe carries water to the field.
• Thinner pipes run along each row of plants.

• Emitters on these pipes let water fall drop by drop onto the root zone.

• Result: very little water is lost.

• Less water evaporates and less soaks away below the roots, because only the root zone is wetted.
• It saves 40-70% of water and fertiliser. Micro-irrigation as a whole saves about 30-50%.

Fertigation: the extra benefit

• Fertigation means mixing fertiliser into the drip water.
• The fertiliser reaches the roots directly, in small and controlled doses.
• So less fertiliser is wasted. That is why the saving covers fertiliser as well as water.

Conditions and crops it suits

• It works best for row crops and widely spaced plants, where each plant or row can get its own line of emitters:
• orchards (fruit trees)
• vegetables

• sugarcane and cotton

• It is most useful where water is scarce or costly, such as drought-prone areas and places with falling groundwater.

• Farmers have to buy pipes and emitters, so the cost is high at the start. Government subsidy helps them pay for it.

Place in government policy

• Pradhan Mantri Krishi Sinchayee Yojana (PMKSY, 2015-16) is the central scheme to bring irrigation to every farm.
• Its Per Drop More Crop (PDMC) component pushes water-use efficiency on the farm through micro-irrigation (drip and sprinkler).
• PDMC ran under PMKSY from 2015-16 to 2021-22. From 2022-23 it has been carried out under the Rashtriya Krishi Vikas Yojana (RKVY) [3].
• Subsidy: 55% of the cost for small and marginal farmers and 45% for other farmers [2].
• Micro Irrigation Fund (MIF): set up with NABARD in 2018. It gives states a 2% interest subvention (a cut in the interest rate) on their loans [2].

Where it occurs

• Leading micro-irrigation states in India: Maharashtra, Karnataka, Andhra Pradesh, Rajasthan and Gujarat.
• Crop belts where drip fits well: orchards and vegetable farms, and sugarcane and cotton fields.
• Water-stressed regions where it is needed most:
• Punjab and Haryana: wells and tubewells water 76.1% and 51.3% of the net irrigated area, and water tables are falling fast.

• Drought-prone areas: the north-west (Rajasthan, parts of Gujarat and Haryana) and the Deccan Plateau.

• Scheme reach: from FY16 to December 2024, ₹21,968.75 crore was released under PDMC and 95.58 lakh hectares came under micro-irrigation. That is about 104.67% more than before PDMC [2].

• World: Israel, a dry country, is the best-known example of drip irrigation.

Don't confuse with

• Sprinkler irrigation: this sprays water under pressure through nozzles, so it falls like rain. It suits uneven land and sandy soils (Rajasthan, Haryana). Drip gives water drop by drop at the roots, suits row crops and orchards, and saves more water.
• Flood irrigation: this covers the whole field with water. It wastes water and causes waterlogging and salinity. Drip wets only the root zone.
• Micro-irrigation: this is the umbrella term for both drip and sprinkler, and it saves about 30-50% of water. Drip is one type of micro-irrigation, and its own saving is 40-70%.
• Per Drop More Crop vs Har Khet Ko Pani: both are parts of PMKSY. PDMC is about efficiency (micro-irrigation). Har Khet Ko Pani is about new water sources and field channels.

Prelims Hooks

• Drip (trickle) irrigation saves 40-70% of water and fertiliser. Micro-irrigation as a whole saves about 30-50%.
• Fertigation (fertiliser given through the irrigation water) goes with drip, not with flood irrigation.
• Drip suits orchards, vegetables, sugarcane and cotton. Sprinkler suits uneven land and sandy soils (Rajasthan, Haryana). This is a common matching trap.
• Micro-irrigation is promoted by Per Drop More Crop, a PMKSY (2015-16) component. It has been carried out under RKVY since 2022-23 [3].
• PDMC subsidy: 55% for small and marginal farmers and 45% for others [2]. NABARD's Micro Irrigation Fund (2018) gives a 2% interest subvention [2].
• Leading micro-irrigation states: Maharashtra, Karnataka, Andhra Pradesh, Rajasthan, Gujarat.

Mains Points

• Demand management is the answer to the water squeeze (GS-III):
• Agriculture uses 89% of surface water and 92% of groundwater.
• NCIWRD expects demand to reach about 1,180 cubic km by 2050, close to the utilisable limit of about 1,122 cubic km.

• So drip irrigation and other efficiency measures matter more than building new supply.

• A fix for groundwater stress in the Green Revolution belt (GS-I/III):

• Heavy pumping from tubewells in Punjab and Haryana has made water tables fall.
• Moving to drip for row crops, together with crop diversification, can cut the amount of water taken out.

• Drip also avoids the waterlogging and salinity that flood irrigation causes in canal areas.

• What drip still needs to spread (GS-III):

• Micro-irrigation reached 95.58 lakh ha by December 2024 [2].
• Pipes and emitters cost a lot at the start, so it still needs:
  • subsidy that reaches small and marginal farmers
  • cheap state loans through the MIF
  • solar pumps to run the system

Related concepts

• Sectoral water use
• Need for irrigation in India
• Pradhan Mantri Krishi Sinchayee Yojana
• Sprinkler irrigation
• Micro-irrigation
• Virtual water

Read more

• Water demand: sectoral use, irrigation need and efficient irrigation