Sustainable Irrigation Methods for Farming

Sustainable irrigation refers to any activity or practice relating to irrigation such that it helps to satisfy the welfare and survival needs of the present without compromising the needs of future generations. It could be irrigation of agricultural areas, ornamentals, and landscapes.

I. An Introduction to Farming

Farming is an integral part of Agriculture, and it involves crop cultivation and rearing animals. Humans have been practicing farming ever since the human ancestors who were hunters and gatherers tried planting wild crops thousands of years ago. Ever since that time, farming has been the source of food and health for the world population. Different types of farming practices are carried out in other parts of the world and influenced by a wide range of factors such as soil fertility and climate.  

Irrigation has been able to significantly increase farming output over the year. However, water is a scarce resource and therefore requires sustainable irrigation practices to conserve water. 

II. What is Irrigation?

Irrigation is a farm practice that involves applying water on crops using pipes, sprinklers, water canals, and other human improvised channels when precipitation is minimal. Typically, zones that receive low rainfalls can not sustain farming without using irrigation. Similarly, irrigation helps in improving the quality and growth of crops in places facing irregular rains. Additionally, irrigation enables farmers to grow crops throughout the year, creating a more reliable food supply in all seasons.

Irrigation is as old as farming itself. It is an ancient practice, and old civilizations practiced irrigation. Traditionally, humans used buckets and pots to carry water from the rivers and wells to pour on their crops. As people developed, they developed sophisticated techniques for irrigation. For instance, Egypt and china developed dikes, canals, and other water storage channels. Ancient Rome was the first to introduce aqueducts that they used to ferry water from melted snow to the residential areas for domestic purposes that included irrigation.

In the modern world, irrigation techniques use tanks, boreholes, and water reservoirs for crop irrigation. Reservoirs include basins, aquifers, lakes, and basins built by dams. By gravitational force, the constructed artificial waterways and pipes carry the collected water to crop fields. Also, in some cases, pumps are used to move water.

After channeling water to the field, there are many irrigation systems that include:

• Surface irrigation
• Drip irrigation
• Localized irrigation
• Sprinkler irrigation
• Lateral irrigation
• Center pivot irrigation
• Manual irrigation
• Sub-irrigation

Rapid desertification in the recent past has increased the size of land in need of irrigation. Globally, 18% of land under crop farming use irrigation. Statistics indicate that the most affected continents are Asia, Africa, and South America. As the need for food rises, there's a need for increased agricultural space and irrigation. As such, the underground water is at the risk of depletion.

1. How Does the Irrigation System Work?

An irrigation system is a design used to deliver water to a designated area. The system is generally applied in farming and landscaping activities. The system encompasses four main stages:

• Main pumping station
• Conveyance system
• Distribution system
• Field application system
• Drainage system.

The Main Pumping Station (Intake Structure)

The pumping station water is channeled from the primary source (reservoir) to the main irrigation system. However, in some instances, the source of irrigation water may be lying lower than the irrigated fields. In such a case, a pump has to be used to drive water to the irrigation system. There are many types of pumps, but the most commonly used in irrigation is the centrifugal pump. 

Water Conveyance System

Once water is collected at the pumping station, it is distributed through the irrigation field. Water is carried through open canals. The canal could either be earthen (only open ground) or lined (fitted with impermeable materials). The primary aim is to channel water from one point to another on the farm. Depending on the shape of the cross-section, a canal can assume different shapes such as triangular, trapezoid, circular, etc. 

Water flowing through canals has to be controlled, and therefore canals are fitted with specific structures that regulate the amount of water flowing. 

Field Application System

You can apply water to your field crops through different methods. The simplest, though tedious, involves fetching water from a reservoir or well with a bucket and directly irrigate the crops. In larger irrigation schemes, more advanced systems are put into place. There are three major irrigation systems: 

• Surface irrigation,
• Sprinkler irrigation
• Drip irrigation.

Drainage System

When the irrigation water is excess on the cropland, a drainage system serves to get rid of it. The excess may be a result of the system's leakage or rain surface runoff. If the excess water is on the surface, shallow open drains are put to drain it. On the other hand, underground pipes are used to get rid of excess underground water.

2. Benefits of Irrigation System

Water is lost by more than 50% through both runoff and evaporation when you

carry out irrigation by hand. Therefore, an improved irrigation system comes with several benefits, not only saving water and reducing costs. 

By 1986, the agricultural land under irrigation globally was 271 million hectares compared to 94 million hectares in 1950. The figures show the importance of irrigation on crop production. While some regions enjoy fertile soils suitable for crop production, they can fail to receive enough rain at the right time of the year. Other areas may experience rains in seasons not favorable to crop farming. In such a case, rainwater can be stored in reservoirs to be used for irrigation.

Additionally, irrigation helps in ensuring food security through increased crop yields. Many regions that use irrigation in crop farming have seen more job opportunities created. The farms engage the nearby population for the labor required in running the farm activities. Studies indicate that land under irrigation becomes productive and hence appreciates.

As agricultural activities diversify and intensify, the existing tree cover is cleared to pave the way for farms. For instance, the area under forest cover in Northern Thailand reduced by half as cassava production was scaled up. However, irrigation scales down the need to cut down trees to produce more, and it also curbs other associated problems like soil erosion.

There are benefits of both underground and surface water for irrigation. Though surface water is subject to different supply levels, it's cheaper to extract and channel to the farm. On the other hand, groundwater is costly to generate, but its supply is steady. If the source of water is an aquifer or reservoir, their use depends on the recharge rate. Either way, joint utilization of the two sources is recommended.

3. Common Irrigation Methods

There are three main types of irrigation: surface, drip or micro, and sprinkler irrigation.

Surface Irrigation

It's a system that depends on the gravitational pull to distribute water through canals to the crop fields. Sometimes, water may need to be pumped from the reservoir to higher levels in the farm. Typically, surface irrigation is ideal for orchards, field crops, and pastures. The efficiency of surface irrigation depends on factors such as:

• Soil type
• Field topography
• Type of crops grown
• Field management practices

Surface irrigation is regarded as less effective compared to sprinklers and drip. But when adequately managed on uniform soil with a reuse system, the results are excellent. There are two types of surface irrigation they include:

• Furrow irrigation
• Basin and border

Sprinkler Irrigation

In this type of irrigation, water is sprayed or sprinkled into the field. Pressurized water is channeled to the system via underground pipes. The sprinkler irrigation system is applied in various crops, including turf, vegetables, field crops, orchards, pastures, etc. The system is also used when applying wastewater, protecting crops from frost, and dust control in enclosed animal management practices. 

Sprinkler irrigation systems control water more efficiently hence regarded as an ideal than surface irrigation. However, on a windy day, the system is prone to lose a large amount of water due to wind rift. There are three categories of sprinkler irrigation system:

• Solid-set sprinkler
• Set move sprinkler
• Moving sprinkler

Micro-irrigation

It is a system of irrigation that distributes water on crops at a low rate and pressure on calculated positions so that the water reaches the target shoot. From pipes, the water drips from small holes (emitters) to wet a desired part on the ground. Micro-irrigation is ideal for tree irrigation, shrubs, and vineyards.

In most cases, the system is automated to ensure that water is continually applied to the crops. Filtration is fitted in micro-irrigation to prevent sedimentation that would block the emitters. Also, chemical treatment is recommended to control salt and mineral buildup on the plugs.

III. The Importance of Sustainable Irrigation

A. Water Waste in Agriculture

Global statistics show that 70% of annual water consumed goes to farming. Of the 70% consumed in agricultural activities, 40% goes to waste via evaporation and poor irrigation practices and channels. As the human population continues to increase, the demand for agricultural farm produce is also increasing.

It is estimated that about 40% of the water used every year is underutilized and goes to waste due to outdated irrigation practices. Some systems, such as overhead sprinklers, shower large field crops, and about half of the water used is continuously evaporated, lost in transit, or end up as runoff.

Water that would be used for other purposes is channeled back to the ecosystem, where it has to be reacquired and distributed again, leading to a waste of money, time, and energy.  

In the US, for instance, agriculture production accounts for about 80 percent of the consumptive water use in the country. Consumptive water use refers to the water used but is not returned to its original source. On the other hand, water used in our homes or an industry like agriculture, approximately 90 percent is finally returned to the ecosystem where it replenishes water sources and could be used to serve other purposes. 

Most countries that practice irrigation agriculture do not consider the amount and cost of the water they spend annually. Intensive underground water pumping is the leading cause of aquifer depletion. The governing authorities need to instill measures that improve the efficiency of water use in agricultural practices.

As the desert encroachment continues to pose a risk in most of California, farmers heavily rely on underground water to run their farming activities. So the question on the table is, "what sustainable irrigation methods can farmers embrace and step down irrigation water waste? 

B. Factors to Consider When Choosing Farm Irrigation Methods

Most irrigation methods feature two systems: The sprinkler and micro-irrigation system. The sprinkler comprises the center pivot, traveling gun, solid set, and linear move. On the other hand, the micro-irrigation system could either be drip irrigation or micro-sprinklers. None of these irrigation systems is better than the other because none are suitable for all fields. The following are some of the factors that can determine the type of irrigation system used in a particular place.

• Type of crops grown
• The cost and availability of fuel
• Installation cost
• Labor intensity
• The acreage and shape of the farm
• Water sources
• Type of technology

IV. Sustainable Irrigation Methods

The amount of water utilized in irrigation varies significantly depending on several factors such as climatic conditions, type of crops grown, and the irrigation system used. While several farm irrigation systems, flood and furrow systems are regarded as the least efficient irrigation practices because so much water is lost through percolation and evaporation. Similarly, the irrigated plants do not receive water evenly.

To curb excess water loss, we must employ more efficient systems such as drip, sprinkler, and micro spray types of irrigation. Though expensive and tech-demanding, these systems use the least water resources adequately.

 Besides, sustainable irrigation systems lead to higher crop production because water is directly channeled to where it's most required. A well-installed drip system will save water by 80% compared to the standard irrigation system.

While many farms rely on town municipal supplied or underground water, some have gone a step further to establish their ponds and store rainwater which they use for irrigation and a habitat for wildlife.

References

AFBFA - American Farm Bureau Foundation for Agriculture. (n.d.). Do farmers waste water? AFBFA 2021. Retrieved May 25, 2021, from https://www.agfoundation.org/common-questions/view/do-farmers-waste-water

Balsom, P. (2020, September 29). Water Usage In The Agricultural Industry. High Tide. https://htt.io/water-usage-in-the-agricultural-industry/

Bjorneberg, D. (2013). IRRIGATION | Methods. Reference Module in Earth Systems and Environmental Sciences, 273–280. https://doi.org/10.1016/b978-0-12-409548-9.05195-2

CDC. (n.d.). Types of Agricultural Water Use | Other Uses of Water | Healthy Water | CDC. Retrieved May 24, 2021, from https://www.cdc.gov/healthywater/other/agricultural/types.html

FAO. (n.d.-a). CHAPTER 5 - IRRIGATION SYSTEM. Food Agricultural Organization. Retrieved May 25, 2021, from http://www.fao.org/3/R4082E/r4082e06.htm

FAO. (n.d.-b). CHAPTER 7. CHOOSING AN IRRIGATION METHOD. Food Agriculturaal Organization. Retrieved May 25, 2021, from http://www.fao.org/3/s8684e/s8684e08.htm

InTeGrate. (n.d.). Irrigation Efficiency. Student Materials. Retrieved May 25, 2021, from https://serc.carleton.edu/integrate/teaching_materials/food_supply/student_materials/1096

National Geographic Society. (2012, October 9). irrigation. https://www.nationalgeographic.org/encyclopedia/irrigation/

New Zealand. Ministry of Agriculture and Forestry. (1997). Best Management Guidelines for Sustainable Irrigated Agriculture. MAF.

OECD. (n.d.). Water and agriculture - OECD. Organisation for Economic Co-Operation and Development. Retrieved May 25, 2021, from https://www.oecd.org/agriculture/topics/water-and-agriculture/

Risse, M. L. (2007, January 1). Considerations for Subsurface Drip Irrigation Application in Humid and Sub-humid Areas. University of Georgia Extension. https://extension.uga.edu/publications/detail.html?number=B882&title

Schoengold, K., & Zilberman, D. (2004, January 1). Water and Development: The Importance of Irrigation in Developing Countries. ResearchGate. https://www.researchgate.net/publication/255573218_Water_and_Development_The_Importance_of_Irrigation_in_Developing_Countries

Shiozaki, J. (2014, August 20). 10 Ways Farmers Are Saving Water. CUESA. https://cuesa.org/article/10-ways-farmers-are-saving-water

The World Bank. (2020, August 5). Water in Agriculture. World Bank. https://www.worldbank.org/en/topic/water-in-agriculture

USGS. (n.d.-a). Irrigation Methods: Furrow or Flood Irrigation. Retrieved May 25, 2021, from https://www.usgs.gov/special-topic/water-science-school/science/irrigation-methods-furrow-or-flood-irrigation?qt-science_center_objects=0#qt-science_center_objects