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Irrigation

by Robert Hijmans
Published: Last Updated on
irrigation

Irrigation is the process of artificially supplying water to land or crops to help grow crops or vegetation. It is often used in areas where there is not enough natural rainfall to support agriculture, or where the soil does not retain enough moisture to sustain crops.

There are several different types of irrigation systems, including surface irrigation, which involves channeling water over the surface of the soil, and subsurface irrigation, which involves watering plants from below the surface of the soil. Other methods of irrigation include drip irrigation, sprinkler irrigation, and pivot irrigation. Irrigation can be an important tool for improving crop yields and increasing the productivity of agricultural land.

Etymology

The word “irrigation” comes from the Latin word “irrigare,” which means “to moisten” or “to water.” It is derived from “ir,” which means “water,” and “rigare,” which means “to moisten.” The word has been in use in English since the 16th century and has been used to refer to the artificial watering of land or crops for agricultural purposes.

History of irrigation

Irrigation has been used for thousands of years to support agriculture and sustain human settlements in arid and semi-arid regions. The earliest known use of irrigation dates back to ancient civilizations in Mesopotamia, Egypt, and China, where irrigation systems were developed to support the growth of crops and sustain human settlements in areas with limited natural rainfall.

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In ancient Mesopotamia, which is now modern-day Iraq, irrigation was used as early as 4000 BCE to support the growth of crops such as wheat, barley, and vegetables. The ancient Mesopotamians used a system of canals and dikes to channel water from the Tigris and Euphrates Rivers to their crops. This system, known as the “qanat,” was used extensively in the region and remained in use for thousands of years.

History of irrigation

In ancient Egypt, irrigation was used as early as 2500 BCE to support the growth of crops such as wheat and barley. The ancient Egyptians used a system of canals and dikes to channel water from the Nile River to their crops. This system, known as the “shaduf,” involved using a counterweighted bucket or scoop to lift water from a lower to a higher level.

In ancient China, irrigation was used as early as 2000 BCE to support the growth of crops such as rice and wheat. In the Americas, irrigation was used by ancient civilizations such as the Maya, who used a system of canals and reservoirs to irrigate their crops. The Inca civilization in South America also developed an extensive system of irrigation to support their agriculture.

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Over the centuries, irrigation systems have evolved and become more complex, with the development of new technologies and techniques.

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Global statistics about irrigation

Irrigation is a vital tool for agriculture and is used to artificially supply water to land or crops in order to improve crop yields and increase the productivity of agricultural land. According to the United Nations Food and Agriculture Organization (FAO), irrigation is used on approximately 38% of the world’s agricultural land, and it is estimated that irrigation has contributed to a 50% increase in global food production over the last century.

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The most common type of irrigation system is surface irrigation, which is used on approximately 22% of the world’s irrigated land. Drip irrigation is the second most common type of irrigation system and is used on approximately 16% of the world’s irrigated land.

Global statistics about irrigation

Irrigation is especially important in arid and semi-arid regions, where natural rainfall is insufficient to support agriculture. According to the FAO, the majority of the world’s irrigated land is located in Asia, which accounts for approximately 60% of the world’s total irrigated area. Other regions with large areas of irrigated land include Europe, North and South America, and Africa.

  • The total area of irrigated land worldwide is approximately 18.8 million hectares.
  • The total amount of water used for irrigation worldwide is approximately 258 cubic kilometers per year.
  • The main sources of irrigation water are surface water (such as rivers and lakes) and groundwater. Surface water is the primary source of irrigation water in Asia, Europe, and North America, while groundwater is the primary source in South America and Africa.
  • The most heavily irrigated crops worldwide are rice, wheat, and maize (corn). These three crops account for approximately 50% of the total irrigated area.
  • Irrigation is an important tool for increasing food security and reducing malnutrition. Approximately 70% of the world’s food is produced on irrigated land.
  • The efficiency of irrigation systems varies widely around the world. In some countries, up to 80% of the water used for irrigation is lost due to evaporation, runoff, and infiltration. Improving the efficiency of irrigation systems is an important way to reduce water waste and increase the sustainability of agriculture.

It is expected that the demand for irrigation water is expected to increase in the coming decades due to population growth and the expansion of agriculture. This will likely lead to increased pressure on water resources, particularly in areas with limited water availability.

Furthermore, climate change is also expected to have an impact on irrigation. Changes in temperature and precipitation patterns may affect the availability of water for irrigation and the timing of irrigation needs.

Types of irrigation

There are several different types of irrigation systems that are used to artificially supply water to land or crops:

Surface irrigation

This involves channeling water over the surface of the soil, typically through the use of canals, dikes, and channels. Surface irrigation is the most common method of irrigation and is often used for crops that are grown in fields or on slopes. There are several different types of surface irrigation systems, including border strip irrigation, which involves channeling water along the edge of a field, and basin irrigation, which involves creating a basin or depression in the field to hold water. Surface irrigation is well-suited to large, flat fields and is often used in areas with abundant water resources.

Subsurface irrigation

Subsurface irrigation

This involves watering plants from below the surface of the soil, typically through the use of underground channels or pipes. Subsurface irrigation is often used for crops that are grown in greenhouses or in areas with limited space. There are several different types of subsurface irrigation systems, including subsurface drip irrigation, which involves delivering water directly to the root zone of plants through underground pipes and emitters, and subsurface flood irrigation, which involves flooding the soil below the surface of the ground with water. Subsurface irrigation is well-suited to crops that are sensitive to water stress and is often used in areas with limited water resources.

Drip irrigation

This involves delivering water directly to the root zone of plants through a network of pipes, tubes, and emitters. Drip irrigation is often used for crops that are sensitive to water stress, such as fruit trees and vegetables. Drip irrigation systems can be either aboveground or subsurface, and they are often used in combination with other irrigation methods, such as surface or subsurface irrigation. Drip irrigation is well-suited to crops that require precise watering and is often used in areas with limited water resources.

Sprinkler irrigation

This involves delivering water to crops through a network of pipes and sprinklers. Sprinkler irrigation is often used for crops that require a lot of water, such as grass and hay. There are several different types of sprinkler irrigation systems, including center pivot irrigation, which involves using a pivoting sprinkler system to deliver water to crops in a circular pattern, and linear move irrigation, which involves using a series of stationary sprinklers that are moved along a field as the crops grow. Sprinkler irrigation is well-suited to large fields and is often used in areas with abundant water resources.

Pivot irrigation

Pivot irrigation

This involves using a pivoting sprinkler system to deliver water to crops in a circular pattern. Pivot irrigation is often used for large fields, such as those used for growing grain or forage crops. Pivot irrigation systems consist of a central pivot point and a series of sprinklers that rotate around the pivot point to deliver water to the crops. Pivot irrigation is well-suited to large, flat fields and is often used in areas with abundant water resources.

There are many different types of irrigation systems that are used in various regions and for different types of crops. The most appropriate system will depend on the specific needs and resources of the region.

Types of water sources used for irrigation

The availability of water for irrigation depends on a variety of factors, including the local climate, the amount of natural precipitation, and the availability of water resources. In general, areas with abundant water resources, such as rivers and lakes, are more suitable for irrigation than areas with limited water resources. There are several different sources of water that are used for irrigation, including surface water and groundwater:

Surface water

Surface water is water that is found on the surface of the earth, such as in rivers, lakes, and reservoirs. Surface water is a major source of irrigation water and is used on approximately 64% of the world’s irrigated land. Surface water is typically collected and channeled through a system of canals, dikes, and channels to the fields or crops that need to be irrigated. The most common method of surface irrigation is flood irrigation, which involves flooding a field or area with water. Other methods of surface irrigation include border strip irrigation, which involves channeling water along the edge of a field, and basin irrigation, which involves creating a basin or depression in the field to hold water. Surface water is an important source of irrigation water in Asia, Europe, and North America.

Groundwater

Groundwater

Groundwater is water that is found underground in aquifers. Groundwater is a major source of irrigation water and is used on approximately 36% of the world’s irrigated land. Groundwater is typically accessed through wells and is pumped to the surface for use in irrigation. There are several different types of groundwater irrigation systems, including shallow tube wells, which are used to extract water from shallow aquifers, and deep tube wells, which are used to extract water from deeper aquifers. Groundwater is an important source of irrigation water in South America and Africa, as well as in some parts of Asia and Europe.

Waste Water

Wastewater can come from a variety of sources, including households, industries, and agriculture. Wastewater can contain a variety of contaminants, including chemicals, pathogens, and nutrients, and it must be treated before it can be safely reused or released back into the environment.

There are two main types of wastewater: treated wastewater and untreated wastewater.

Treated wastewater

Treated wastewater is wastewater that has been subjected to a process of treatment to remove or reduce contaminants. There are several different methods of wastewater treatment, including physical, chemical, and biological treatment. Treated wastewater is often referred to as “reclaimed water” or “recycled water.” Treated wastewater can be used for a variety of purposes, including irrigation, industrial processes, and landscaping. The use of treated wastewater for irrigation is often referred to as “reuse irrigation.”

Untreated wastewater

Untreated wastewater is wastewater that has not been subjected to any treatment and is still contaminated. Untreated wastewater is not safe for reuse or release back into the environment and must be treated before it can be used or disposed of. Wastewater is not a common source of irrigation water, but it is sometimes used in areas with limited water resources or in situations where other sources of irrigation water are not available. The use of untreated wastewater for irrigation is generally not recommended due to the potential health risks and environmental impacts.

Advantages and disadvantages of irrigation

Irrigation can have both advantages and disadvantages, depending on the specific circumstances and resources of the region. Some of the main advantages and disadvantages of irrigation are:

Advantages of irrigation:

1. Increased crop yields: Irrigation can significantly increase crop yields by providing a consistent and reliable source of water for crops. This is particularly important in regions with limited natural rainfall or where the timing of rainfall is not well-suited to the needs of the crops. According to the United Nations Food and Agriculture Organization (FAO), irrigation has contributed to a 50% increase in global food production over the last century.

Advantages of irrigation

2. Improved food security: Irrigation can improve food security by increasing the availability of food and reducing the risk of crop failure due to drought or other environmental stresses. This is especially important in areas with limited natural rainfall or water resources, where agriculture is often highly dependent on irrigation.

3. Increased agricultural income: Irrigation can increase agricultural income by allowing farmers to grow more valuable or higher-yielding crops, or to grow crops in areas that would otherwise be unsuitable for agriculture.

4. Improved land use: Irrigation can allow for the more efficient use of land by making it possible to grow crops in areas that would otherwise be too dry or have poor soil quality.

5. Greater control over the growing environment: Irrigation allows farmers to have greater control over the growing environment, including the timing and amount of water that is applied to crops. This can help to optimize crop growth and improve the efficiency of agricultural practices.

6. Increased flexibility: Irrigation allows farmers to grow crops in areas that are not well-suited to rain-fed agriculture, such as arid or semi-arid regions. This can provide opportunities for farmers to expand their operations or to diversify their crops.

Disadvantages of irrigation:

1. Water scarcity: Irrigation can contribute to water scarcity by increasing the demand for water and potentially reducing the availability of water for other uses. This is especially true in areas with limited water resources or where irrigation is not well-managed. According to the United Nations Food and Agriculture Organization (FAO), irrigation accounts for approximately 70% of global freshwater withdrawals, and in some regions, irrigation is the primary driver of water scarcity.

3. Financial costs: Irrigation can be expensive, particularly in areas where water resources are limited or where the infrastructure required to deliver water to fields is not in place. This can be a significant financial burden for small farmers and can limit the adoption of irrigation in some regions.

Disadvantages

4. Water waste: Irrigation systems can be inefficient, with some systems losing up to 80% of the water that is applied to crops due to evaporation, runoff, and infiltration. This can lead to the waste of valuable water resources and contribute to water scarcity.

5. Social impacts: Irrigation can have social impacts, such as conflicts over water rights and the displacement of local communities. These impacts can be particularly significant in areas where water resources are limited or where the adoption of irrigation has led to the expansion of large-scale agricultural operations.

6. Water pollution: Irrigation can contribute to water pollution if it is not properly managed. In particular, irrigation can lead to the leaching of fertilizers, pesticides, and other chemicals into water bodies, which can have negative impacts on the quality of water resources and the health of aquatic ecosystems.

7. Soil degradation: Irrigation can lead to soil degradation if it is not properly managed. In particular, irrigation can increase the risk of soil erosion, compaction, and salinization, which can reduce the productivity of agricultural land. In addition, irrigation can lead to the loss of soil organic matter and the decline of soil biodiversity, which can further reduce soil productivity.

8. Pest and disease outbreaks: Irrigation can increase the risk of pest and disease outbreaks by providing a more favorable environment for the growth and reproduction of pests and diseases. In particular, irrigation can create moist and humid conditions that are conducive to the development of fungal diseases.

9. Energy consumption: Irrigation systems often require energy to operate, which can contribute to greenhouse gas emissions and other environmental impacts. In particular, irrigation systems that rely on pumps and other mechanical devices can be energy-intensive and may require the use of fossil fuels.

Alternatives of irrigation

Here are a few alternatives to irrigation and some information on their benefits and potential side effects:

Alternatives

Dryland farming

Dryland farming involves growing crops without the use of irrigation. This method relies on natural rainfall and is commonly used in regions with limited water resources or low levels of rainfall. Dryland farming techniques can include the use of cover crops, mulch, and other practices that help to conserve water and improve soil moisture retention.

Benefits:

  • Can be used in areas with limited water resources
  • Can help to conserve water
  • Can improve soil moisture retention

Potential side effects:

  • May be less reliable than irrigation, as it relies on natural rainfall
  • May not be suitable for all crops or growing conditions

Rainwater harvesting

Rainwater harvesting

Rainwater harvesting involves collecting and storing rainwater for use in irrigation. This method can be used to supplement irrigation in areas with limited water resources or to reduce the demand for irrigation in areas with more abundant water resources. Rainwater harvesting systems can include cisterns, reservoirs, and other storage structures.

Benefits:

  • Can help to conserve water
  • Can reduce the demand for irrigation in areas with abundant water resources
  • Can be used to supplement irrigation in areas with limited water resources

Potential side effects:

  • May not be suitable for all areas, as it relies on sufficient rainfall
  • May require the construction of storage structures, which can be costly

Greenhouses

Greenhouses

Greenhouses are structures that are used to create a controlled environment for the growth of crops. Greenhouses can be used to grow a variety of crops, including fruits, vegetables, and flowers, and can be equipped with irrigation systems to provide a consistent source of water.

Benefits:

  • Can be used to grow a wide range of crops
  • Can provide a controlled environment for plant growth
  • Can be irrigated to provide a consistent source of water

Potential side effects:

  • Can be expensive to construct and maintain
  • May require additional energy to maintain the controlled environment

Drip irrigation

Drip irrigation is a method of irrigation that involves the delivery of water directly to the roots of plants through a network of tubes or hoses. This method is highly efficient and can help to reduce the amount of water needed for irrigation.

Drip irrigation

Microirrigation

Microirrigation is a type of irrigation that uses small amounts of water to irrigate specific areas of a field or garden. Microirrigation systems can include drip irrigation, sprinkler irrigation, and other methods that deliver water directly to the roots of plants.

Benefits:

  • Highly efficient, as it delivers water directly to the roots of plants
  • Can help to reduce the amount of water needed for irrigation
  • Can improve crop yields

Potential side effects:

  • May require the installation of a network of tubes or hoses, which can be costly
  • May be prone to clogging or other issues if not properly maintained

Aquaponics

Aquaponics is a system that combines hydroponics (the cultivation of plants in water) with aquaculture (the farming of aquatic animals). Aquaponics systems can be used to grow a variety of crops, including fruits,
vegetables, and herbs, and can be irrigated with water that is circulated through the system.

Benefits:

  • Can be used to grow a variety of crops, including fruits, vegetables, and herbs
  • Can be highly efficient, as the water used in the system is circulated and reused
  • Can be a sustainable and environmentally friendly method of food production
  • Can be used in areas with limited space or soil quality

Potential side effects:

  • May require additional infrastructure, such as tanks or grow beds, to operate
  • May require additional inputs, such as feed for the aquatic animals, to operate
  • May require additional management and maintenance to ensure that the system is operating properly.

Future of irrigation

The future of irrigation is likely to involve the increasing use of modern irrigation technologies and practices that are more sustainable and efficient. This may include the use of precision irrigation technologies, such as soil moisture sensors and weather-based irrigation controllers, which can help to optimize irrigation schedules and reduce the amount of water needed for irrigation. According to a study by the International Water Management Institute (IWMI), precision irrigation technologies can reduce water use by up to 30%, which can lead to significant water savings and cost reductions for farmers.

Future of irrigation

In addition, the use of alternative irrigation methods, such as drip irrigation and microirrigation, is likely to continue to grow, as these methods are highly efficient and can help to reduce water use and improve crop yields. A study by the International Fertilizer Association (IFA) found that drip irrigation can increase crop yields by up to 50%, while reducing water use by up to 70%.

The role of modern irrigation technologies and practices will be crucial in addressing the challenges of climate change and population growth, which are expected to increase the demand for food and water in the coming decades. Modern irrigation technologies and practices can help to improve the efficiency of water use and reduce the environmental impacts of irrigation, such as water resource depletion and water pollution. In addition, the use of precision irrigation technologies and alternative irrigation methods can help to improve crop yields and support the sustainable production of food.

Conclusion

Irrigation is a technique used to artificially supply water to land in order to support the growth of crops. It is an essential part of agriculture, as it enables farmers to grow crops in areas with limited or unreliable rainfall. There are many different types of irrigation systems, including surface irrigation, sprinkler irrigation, and drip irrigation, and these systems can be powered by a variety of water sources, such as rivers, lakes, and wells. While irrigation is a valuable tool for supporting crop growth, it can also have negative impacts on the environment, such as water resource depletion and water pollution. Therefore, it is important to use irrigation responsibly and consider alternative methods, such as dryland farming, rainwater harvesting, and water conservation techniques, to minimize its environmental impact.

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