Frequently Asked Questions about Irrigation (FAQs)

FAQ’s on Irrigation / Frequently Asked Questions About Irrigation:

Many people are requestioin to post about Frequently Asked Questions About Irrigation (FAQs). Here are most common questions and answers  of irrigation in agriculture, farming, and gardening.

1. What is meant by irrigation?

The process of applying a controlled amount of water or required quantity of water to the plants at specified or periodic interval of time is called irrigation. This process is an integral part of agriculture that keeps the farm land moist for the plants to grow and also solves the problem of dry areas, which lack proper rainfall.

2. What are the different types of irrigation?

There are different types of irrigation systems depending on the soil type, water requirement, weather of the region etc. They are:

• Surface irrigation
• Micro irrigation
• Sprinkler irrigation
• Sub irrigation

3. Why is irrigation important and where is it used?

Irrigation is required to supply water to large farmlands where there is no availability of watering the crops from any other resource especially when the rainfall is scanty. Most important uses of irrigation are:

• Providing proper, uninterrupted and adequate water to the farmlands.
• Increases the productivity of farm.
• Irrigation ensures sowing seeds at the required moisture level.
• Helps in multiple cropping throughout the year.
• Modern methods have facilitated the supply of water to the roots which is exclusively important for the plant growth.
• Fertilizers can also be mixed in the water before irrigation this reduces the task of fertilizing the crops separately.
• Large farmlands can be developed.
• It is the most important resource for farming in the drought stricken areas.

4. What are the disadvantages of irrigation?

There are potential side effects also linked with irrigation such as:

• Water logging in the farms.
• Increase or decrease in pH levels of the soil.
• Poor aeration to the soil because of too much moisture.
• Polluted water can pollute the underground resources.
• Irrigation in cooler regions of the country can cause disease outbreaks due to stagnant water.
• Fertilizers can sometimes get into the source of water and cause eutrophication.
• If the water in the reservoir dries up due to evaporation, then it could result in a dry land.
• Using the river water entirely for irrigation can disturb the local ecology.

5. What is modern irrigation?

Modern irrigation generally indicates the use of new improved equipment for carrying out irrigation in the farmlands. The traditional techniques of irrigation were not able to irrigate the entire land, especially in the boundaries and depressions. The modern equipment facilitates enhanced use of resources and reduces the human labour for irrigating the fields. Modern irrigation systems are equipped with timers and sensors to predict and deliver the amount of water required by the crops in the fields. Sprinkler irrigation is an example of modern irrigation method.

6. How do irrigation systems move?

Some irrigation system is designed to address the needs of extremely large farmlands and with a higher canopy, this may require movement of the irrigation system. The two movable irrigation systems are center pivot and lateral move. As the name indicates, the center pivot system is fixed at one end and rotates around the fixed point, whereas lateral move systems are completely movable with a certain speed.

7. What is lift irrigation system?

Unlike the normal irrigation systems where water flow is natural (gravity flow); here water is transported or lifted through pumps or surge pools. This system works as two parts: the one where the water is carried from the source through pumps to the delivery chamber and second water is distributed from the chamber to the fields. It requires 3 things or components such as water source, lifting medium (pump) and conveying medium (pipes).

8. What is localised irrigation?

The term localised indicates specified area (roots of the plants). The process of irrigating or wetting the soil exactly at the point of the roots to facilitate proper growth and reduce water wastage is called localised irrigation. Small nozzles, tubes, perforated pipes are used for localised irrigation to water a small area of land around the plants.

9. What is gravity irrigation?

Gravity system is a basic irrigation system consisting of an elevated reservoir, the pipe from the bottom of the reservoir to the irrigation system which can be either hand operated or battery operated to control the time and rate of water application. The reservoir of the gravity system is filled by harvesting rainwater.

10. What is river lift system?

It is a kind of lift irrigation system where the source of water is rivers. Supplying water to the plants or crops is not done in a natural way rather the river water is lifted by pumps and then supplied to the plants. It is exclusively used in regions where the water from canals, reservoirs is insufficient to water the farmlands.

11. What are the main sources of irrigation?

Water for irrigation can have many sources like groundwater (springs and wells), surface water (rivers, lakes, reservoirs), water from non-conventional sources (treated water, wastewater, recycled water, desalinated water) etc. Farm lands can also be irrigated with flood water that is cautiously stored in dams, channels, etc. Some regions of the world collect and use rainwater as a source of irrigation called as rainwater harvesting, but this is not accepted as a form of irrigation.

12. What is flood irrigation system?

Water is supplied to the fields by pipes or ditches such that the water flows over the ground through the crops. It is not an effective way of irrigating the crops because only 50% water irrigates the crops while the remaining gets evaporated or is lost through transpiration of the leaves. Flood irrigation could be beneficial if the fields are levelled, surge flooding is applied and the runoff water is recycled. Installing sensors along with surge irrigation can improve the efficiency of flood irrigation systems because it would then be indicated to the cultivator when the irrigation supply has to be stopped.

13. What is furrow irrigation and what is the slope and spacing of the furrow system?

When cropping is done by creating rows and furrows in the farm, then this furrow irrigation system is used, such that water is supplied or made to flow down the furrows and it seeps into the soil horizontally and vertically thereby filling the soil reservoir. This is an economical way of irrigation where the flow of water is controlled manually. The slope for the furrow irrigation should be around 0.5%. For sandy soil, the recommended spacing of furrows is 30 cm (coarse sand) and 60 cm (fine sand). Similarly for clay soil type, the spacing between furrows should be around 75-150 cm.

14. What are the advantages and disadvantages of furrow irrigation?

The major advantage of furrow irrigation is low investment and pumping cost per acre-inch of water pumped. The major disadvantage is the need for labour and lower application efficiency when compared to other irrigation systems.

15. What percentage of water is used in irrigation?

It is observed that irrigation is the most important use water and approximately 70% of the water from world’s fresh water resources is being used in irrigation.

16. What is drip irrigation system?

Water is allowed to trickle onto the soil surface at very low rates i.e.2 to 20 litres per hour through small plastic pipes fitted with drippers. This system of irrigating plants, supplies water close to the root areas and provides the required moisture and nutrients for growth. Since water is supplied in limited quantities, frequency of application is high (every 1-3 days).

17. How much pressure is needed for drip irrigation and what should be the spacing of emitters in the system?

The minimum pressure range on which the drip irrigation systems work are 10-30 pounds per square inch. This pressure is an average standard pressure for the design of all drip irrigators. The general rule of thumb is to install emitters under 80% of the leaf canopy with a spacing of 600 mm. If the land has permeable soil then the minimum spacing should be around 300 to 450 mm. Depending of the discharge of water from the pipes emitters spacing is decided for each type of soil. 4litres per hour emitters need a spacing of 60 cm for coarse soil, 1 m for medium soil and 1.3 m for fine soil. Similarly, 2 litres per hour emitters are spaced 30 cm for coarse soil, 60 cm for medium soil and 1 m for fine soil.

18. What is sprinkler irrigation system?

Applying water to the plants in the form of rain is the main idea of sprinkler irrigation systems. The distribution of water is generally done through pipes by pumping action and then water is sprayed into the air so that the water droplets fall to the ground and irrigate the area. These systems have different discharge capacities and hence they can be used in farm lands with different types of soil structures.

19. How does an underground sprinkler system work and how much water does it use?

The entire network of pipes for the sprinkles systems is buried under the ground at a depth of 12 inches and certain zones in the farmland are selected for installing the retractable sprinkler heads. The pressure structure of the system is such that the water passing through the pipes is forced to emit above the ground through the sprinkler heads. On an average it is estimated that a sprinkler pipe of dimensions ⅝ inches uses around 1020 gallons of water in one hour.

20. How much pressure is in a sprinkler system?

The units of pressure are pounds per square inch (psi). Sprinkler irrigation systems are designed to use an average pressure of 30 psi and this is measured at the farm using a flow meter or water gauge. Low pressure ensures better functionality. All the components of the sprinkler system are designed to work at the same pressure levels. Higher pressure may lead to mist or fog in the spray head area.

21. How does surface irrigation work?

It is considered as the least complex form of irrigation in which water is distributed over the surface of the soil by gravity. There are three different forms of surface irrigation such as basin irrigation, border irrigation and furrow irrigation. Water is made to flow from a higher level along the edge of the field such that it covers the entire farm land. There is no pipeline used in surface irrigation, rather soil in the farm is adjusted to make way for the water flow.

22. What are the advantages and disadvantages of surface irrigation systems?

The advantages of the system are:

• Easy to understand and maintain the system
• Less capital investment
• Facilitates the flow of water due to the presence of essential elements at the edges of the farm.
• Works better in non-suitable topographical areas with minimal costs.
• Gravity is the most important factor for these systems.
• Less affected by climate and quality of water.
• Flexible and easy to use.

Disadvantages of the system are:

• Property of the soil may vary/change the water flowing capacity.
• Considered less efficient than other systems.
• Grading the field prior to surface irrigation is needed.
• Labour intensive.

23. What is micro irrigation system and what are they?

The technique of supplying small quantities of water to the soil surface in the form of continuous drops through well designed emitters along the rows of plants is called a micro irrigation system. To name a few micro irrigation systems are drip irrigation systems, sprinkler systems, micro jets, gravity fed systems etc.

24. What is a micro spray irrigation system?

Generally a micro spray irrigation system is considered to be a combination of surface spray and drip irrigation systems. The system operates at very low pressure of 15 to 30 psi and supplies low volume of water with application rates of 5 to 70 gallons per hour. The system consists of micro tubes with a series of nozzles attached to risers. Unlike the drip irrigation system, it doesn’t wet only the roots of the plants, but facilitates water to large areas because of spraying action.

25. What is the average cost of an irrigation system?

Each system of irrigation has a different price structure and this largely depends on the area of land, the components of the system required and the availability of the systems in different parts of the country. For example, a drip irrigation system would cost around Rs 60,000-75,000 per acre of a vegetable farming, whereas the same system would cost around Rs 35,000 per acre for a fruit farming. Trusted dealers of various irrigation system brands should be consulted for individual farm needs before making a decision on the investment cost of irrigation.

26. What is the best irrigation system for a vegetable garden?

Sprinkler systems are considered to be the best for vegetable gardens or farms with sandy soil structure, but otherwise a hose is used to water the vegetable farm such that each plant could soak water at least 6 inches deep. For plants that need a constant water supply or utilize more water can be irrigated using furrows, basins or drip systems.

27. What are the uses of drip and spray irrigation?

Some of the common benefits of drip and spray system are:

• The precise amount of water is delivered to each plant.
• Evaporation loss is reduced by mulching the farms when using these irrigation techniques.
• Less water usage.
• No pollution from runoff.
• Improves plant health.
• Delivers fertilizers directly to the plant base.
• Can be used for a wide range of soil structures.
• Large areas of farmlands can be watered at once.
• Low installation charges.
• Low pressure operators.

28. Where is center pivot irrigation used and how many acres does it cover?

This is also referred to as the water wheel and circle irrigation in which crops are watered by an equipment that rotates on a pivot fixed at the center. As the equipment moves in a circular direction, it is capable of irrigating the land around it through sprinklers. Electric motors are used to propel the center pivots. It belongs to the form of overhead irrigation.

The length of a center pivot is less than 1600 ft, typically around 400 m or ⅟₄ mile and can cover a radius of 125 acres of land.

29. What irrigation system is considered most efficient?

All the modern irrigation systems are considered efficient depending on the soil, weather and type of cultivation. Each plant has different requirements for water and each system is efficient enough to provide the required quantity to the plants. The efficiency of these systems is better known in places where there is less availability of water sources.

30. What type of irrigation conserves the most water?

The drip system of irrigation supplies one to four gallons of water per hour to the soil directly. The loss of water due to evaporation and runoff is extremely low in drip irrigation and hence it is considered to be the best in conserving water. Other irrigation systems which help conserve water are flood, spray and better spray systems.

31. What is overhead irrigation?

The spray or sprinkler systems are all different forms of overhead irrigation, where basically the water is sprinkled onto the plants from a higher level with certain specified pressure. These overhead irrigation systems are useful for bedding plants, filed crops and container plants that are close to each other. They can be fixed or movable depending on the farm and agriculture farming requirements.

32. What is chain pump system of irrigation?

A water pump having many circular discs properly aligned on an endless chain is called a chain pump. One end of the chain remains in water and the chain moves through a tube with a diameter bigger than the discs. Water gets trapped in between the discs which is lifted and discharged at the top. This is one of the oldest methods of irrigation originating in the Europe and East.

33. What is the cost of sprinkler irrigation in India?

It is estimated that to irrigate one acre of a farm area of sugarcane two rain gun sprinkler heads are to be used, which cost around Rs 3,500 to Rs 5,000 per head and the installation charges per acre of land would be around Rs 15,000 to Rs 20,000 (including pipeline and riser pipe).

34. How can one prevent clogging in emitters?

Almost all irrigation systems use emitters that force water into the soil surface, but micro sprinklers and tape system emitters are free from clogging. Improper management techniques and poor water quality can lead to clogging of emitters or drippers. Clogging can be prevented by:

• Injecting dilute HCl (1%) into the systems.
• Keep the systems functioning at least for 10 minutes every day during the rainy season can lower clogging and improve operation.
• Maintaining the components of the system by regularly cleaning and disinfecting them.

35. What is meant by surge irrigation?

A properly designed furrow irrigation system with predefined ON-OFF time cycles to deliver the required quantity of water is called surge irrigation.

36. What is uniformity in irrigation and why is it important?

The ability of the capacity of the irrigation system to water the plants equally is called uniformity in irrigation. Improper set up can create risk of under-watering or excess watering the plants. To irrigate the plants sufficiently one must install uniform irrigation systems at proper zones in the fields.

37. What is Rahat system of irrigation?

It is a method of irrigation used in the olden times when oxen were involved in getting water to the farmlands. A wheel attached to the well is turned by the oxen or other draught animals to get water out of the well into buckets that could be dumped evenly over the crops to water them. This method was used in Africa and Middle East by their local tribes.

38. What is boom irrigation system?

A boom irrigation system is a collection of pipes with nozzles that can actually move over the plants while watering them. An overhead rail or a cart moving down an aisle is used to make arrangement for this system. A trailing hose supplies water and is powered by a battery or electric supply. The nozzles are spaced 12 to 15 inches apart and can deliver water @ 0.1 to 0.8 gallons per minute with an average pressure of 15 psi.

39. What are different ways of irrigating plans in a Greenhouse?

There are different ways of irrigating a greenhouse, depending on its size and other internal aspects. The methods are:

• Drip tubing
• Overhead misters
• Mat irrigation
• Perimeter irrigation

40. Are there any subsidies available for providing irrigation systems for the farmers?

Yes, there are subsidies available depending on the size of the farm and the type of irrigation system being installed. Government of India has earmarked Rs 5,000 crore as an initial investment to support micro irrigation systems under the ‘Micro Irrigation Fund Scheme’. So people who intend to get financial assistance from the government for installing irrigation facilities in their farms can contact the agriculture department for further details.

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