Irrigation Methods, Types & Importance

What is irrigation?

Irrigation is the process of watering crops, meadows, pastures, and plants by the use of water, which is delivered through pipes, sprinklers, canals, tunnels, sprays, pumps, channels, and other man-made elements, rather than purely depending on rainfall. It is a modern method of a watering system for helping plants to grow because it is applied as a substitute for rain-fed farming. This process supplies specific amounts of water to land to assist in crop development. In dry topographies and during seasons of less rainfall, irrigation aids in the growth of crops or plants, the maintenance of landscapes, and the ecological repair of damaged soils. Irrigation aims at enhanced crop production including frost protection, and weed repression in grain fields as well.

It also satisfies plant or crop water requirements as they need it as a vital resource for growth. At the same time, it helps provide plants with the essential nutrients required for growth and development and targets high yields by enabling the root’s penetration in dry fields.

Importance of Irrigation

The importance of irrigation supplies is discussed as follows.

• Increase in agricultural production and yield.
• Droughts and starvation can be efficiently controlled with irrigation.
• It helps in the production of crops and the repair of damaged soils in dry conditions and during periods of low rainfall.
• The production of irrigated land yields everywhere in the developing world is constantly higher in irrigated areas.
• Moisture is necessary for the germination of seeds as seeds cannot grow in dry soils. With the help of irrigation techniques, the required moisture content of the soil is maintained.
• Multiple cropping through irrigation enhances production & yield. 
• A plant can consume mineral nutrients from the irrigated soils. Thus it is critical for the general growth and development of the plant.
• Bringing more land for agriculture is possible through irrigation.
• Inadequate rain may also cause scarcity & famines. Irrigation can play a defensive role during periods of drought & starvation.

Methods & Types of Irrigation

Conventional methods of irrigation provided the foundation for future development in the agricultural zone. As technologies advanced, farmers began to meet higher crop yields and better production rates overall. Advanced methods of irrigation have been helpful because they brace an individual crop’s specific irrigation requirements, and can be customized to the landscape in which the farming is being done. They also balance the climate of the region to make agriculture more feasible.

1. Surface Irrigation

It is the most familiar type of irrigation as it simply utilizes gravity to distribute the water all over the field by following the profile of the land. In surface irrigation, for instance, water will flow downhill from an area of height, reaching all the vegetation. It is only suitable if the area or the land has enough water, and is naturally sloped. Otherwise, it becomes extremely labor-intensive. It makes use of the furrow system technique, whereby channels/ditches are used to direct water down a slope across a field where crops or plants are grown.

Surface irrigation is not good for highly sandy soils with a high infiltration rate, as it can lead to unchecked water distribution. It ultimately results in floods and soil erosion. Also, it can only work in regions with a huge supply of water.

2. Localized Irrigation

In localized irrigation water is distributed under low pressure, through a piped network, and supplied to each plant. In this type, water is distributed under low pressure to vegetation or crops. Tube networks or pipelines are used throughout the sector, delivering water to each plant.

Localized irrigation is used for wetting small areas, commonly the root zone of the plant as water is delivered just around the base of the crop or plants. The flow rate of the water is extremely low, applied regularly and in small amounts either below or above the soil surface.

The application tools used in localized methods include nozzles, perforated pipes, tubes, nozzles, and holes whereas the main components include pressure, flow controllers, and main lines. Localized irrigation is a highly used method of irrigation owing to 90% due to its high water-saving attribute.

3. Drip Irrigation

Drip irrigation, sometimes referred to as trickle irrigation, is a type of localized method, where splashes of water are delivered directly to or near the plant’s root at an extremely low flow rate.

It is an effective method as it reduces evaporation and water runoff. It is also appropriate for all types of geography and soils and ideal for areas with limited water supply or with high water costs.  

4. Sprinkler Irrigation

As the name indicates, sprinklers are used to irrigate in a way that boosts natural rainfall. The system is exercised in a way that ensures water is applied steadily and uniformly. Overhead pressure sprinklers or guns are used to supply water from a central location in the fields, usually by pumping action.

The sprinklers could also be connected to the moving floor. In center pivot irrigation, for instance, sprinklers are linked to wheeled towers, in a circular arrangement to spray water above plants, and is common in leveled areas. Sprinkler method can be used to irrigate lawns, gardens, crops, and landscapes, and can be used for agricultural, residential, and commercial purposes.

4. Subsurface Irrigation

The soil surface is not made wet in this type. Instead, the water is supplied directly to the ground through capillarity to reduce aerial drift and lessen runoff. In this way, the water table is lifted making it easier for crops to consume the water they require.

Buried pipes or tubes or drip tapes are used to provide for the water needs of the crops or vegetation. Its benefit is that it prevents water loss from evaporation and enhances crop yields by minimizing disease and weeds. 

5. Flood Irrigation

Flood irrigation also known as inundation method is a type of irrigation were flooded land controls are intentionally created, thereby making the soil completely saturated with moisture. After this operation, naturally-occurring rainfall is enough for the maturity of the crops.

6. Perennial Irrigation

Perennial irrigation is a system that is based on a continuous supply of water. A channel distribution system is established, taking off water from a reservoir or fenced to the crops.

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Various Methods of Irrigation

Manual Irrigation

Distributing the water across the land through manual labor and watering cans is known as the manual method. It is a primitive method of watering but is still used today, especially in poor developing countries. It is inexpensive but very labor-intensive, and its effectiveness could be better since there is an unbalanced distribution of water. Also, there are more chances of water loss because of uneven distribution. 

The Sprinkler System

This method is a modern practice which uses systems called sprinklers. A pump called a sprinkler is connected to pipes that generate high pressure and water is sprinkled through the pipes’ nozzles. They sprinkle water over the crops or plants like raindrops or splashes helping to deliver an even distribution of water. This method is effective and serves best in areas with unlimited water resources.

The sprinklers can be set permanently, or temporarily in a place or can be mounted on a movable floor. Depressingly for the system, the water used has to be clean and safe for animals and people. The water distribution can be uneven, weeds get as much water as the crop, and can easily corrode soils if the water floods.

The Drip or Trickle System

In a drip or trickle system, water is provided drop by drop, direct to the roots, using a hosepipe. Drip irrigation is considered one of the most effective methods as its main focus is to supply water to the plant itself.

It is well suited for areas where there is a water shortage. Drip system can use any water, either cleaned or contaminated including recycled and drinkable water, on any type of soil and in any weather. It reduces soil erosion, is energy efficient and cost-effective, and minimizes the weed’s growth as the water reaches the crop itself.

Subsurface Irrigation

This method is applied where irrigation water is supplied below the soil subsurface. It can be done artificially or naturally. As for later, water leaks from the water pipes or tunnels, moving through the subsoil surface and irrigating the crops present nearby.

As for the former, artificial water channels/tunnels are provided underground and water is delivered to the crops through capillarity. It is an expensive means of irrigation but delivers high returns and higher profits margin. Water is diffused across the land by elevating the water table, through a system of pumping actions, canals, gates, and tunnels. This method is most applicable in areas with high water tables.

Perennial Irrigation

Irrigation water is supplied from a river to the main canal through the assembly of a diversion bank. This is also known as direct irrigation, as the water goes straight to the crops. If a dam is built and the water is collected and stored, this is called storage irrigation. Direct method is easy and the most inexpensive form of perennial irrigation.  

Benefits of Irrigation

1. Compensating for when there is no rainfall

It plays its role when there is inadequate rainfall or when there is uncertainty as to when the rainfall will occur. With rain or irrigation as a substitute, the crops are negatively affected, which can lead to crop failure and food shortage. 

2. Enhancing the agriculturally productive land

Few areas of the land are dry, naturally. This system has been liable for turning such dry lands into cultivable lands. Today, about one-third of the world’s cropland is irrigated. It is also responsible for delivering the most out of uncultivated lands, which are habitually left neglected after harvest, before the coming cultivation season.

3. Helps meet food demands

The extension of irrigated land has made desert ecosystems espouse farming to increase food demands without inevitably depending on rain. Such areas use groundwater from aquifers and wells and in doing so, it facilitates them to meet the world’s demand for food and bread by producing food crops such as wheat, potatoes, and vegetables. Moreover, countries and regions that execute top-level and extensive irrigation, are ideal for exporting food, which brings an economic benefit to such a locality.

4. Increased productivity of land

Irrigation, in many cases, is practiced when rainfall is insufficient. However, it can be exercised at any time, even if there is adequate rainfall to enhance crop productivity. Crop productivity on irrigated land skyrocketed in unirrigated areas that rely on rainfall.

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5. Enables multiple cropping

In most tropical countries, the rainy seasons are fixed, making it impractical to grow multiple crops at a time. Additionally, their water requirements are discrete, and over-irrigation hampers crop production. Optimum irrigation makes it practicable to grow more than one crop at a time in localities.

6. It is an effective practice

When plants or crops are watered infrequently and with just mere piping, it is not appropriate and they simply get just one pass. This means out-of-reach areas and those that do not experience balanced rainfall may not get enough water. A well-approached system addresses even to hard-to-reach areas of the land through the effective use of trickkling systems such as drip irrigation.

7. Efficient Nature

If it rains during the day in slightly warm conditions evaporation rates will be at its peak, meaning the crops and the soil will not consume sufficient water. The systems can be practiced in such a way that they shower water early when evaporation rates are low. This, not only saves the water used, but also intensifies the moisture required by the crops, plants, or even the soil itself.

8. Contribute to economic growth

Irrigation assures food production continues, regardless of the weather or climatic condition. This means there is ongoing income and a higher employment rate, thereby bringing down poverty. With the marked increase in revenue achieved through irrigation methods, the economy can continue to boost. This is also reached by the export of food to other regions or countries of the world.