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Flood irrigation is the oldest and most popular irrigation system in the world. Yet flood irrigation is also the most water-intensive method of irrigating crops, an increasing concern as rising temperatures, prolonged drought, and growing populations place more demand on the planet’s finite water resources.
Globally, agriculture uses 70% of the planet’s freshwater resources and 95% of the world’s farmers use flood irrigation. Unfortunately, flood irrigation is the most inefficient of all irrigation systems, including center pivot and drip irrigation systems. Flood irrigation wastes upwards of 50% of the water used.
But, flood irrigation does come with benefits. Evaporation is reduced and it is the most economical and energy-efficient way to irrigate crops. And, some crops thrive under flood irrigation techniques. Plus, new practices and technological advances have found ways to streamline the water efficiency of flood irrigation.
So, should you choose flood irrigation for your farm? Or some other method of irrigation like pivot irrigation, sprinkler irrigation or drip irrigation? Like most things in farming, it depends. Crop needs, water availability, energy resources and economics are factors farmers should weigh when deciding for or against flood irrigation.
Let’s start by diving deeper into the specifics of flood irrigation:
Table of Contents
Flood Irrigation and Terrain Specific Subtypes
Flood irrigation, also called surface irrigation, is any method of irrigation that delivers water to croplands using gravity and is not pressurized, according to Oklahoma State University extension services.
This makes flood irrigation is a low-tech, low-energy irrigation method implemented without a need for sophisticated machinery or expensive infrastructure.
Although all flood irrigation is based on the same basic principle—a non-pressurized system of irrigation—there are different methods of applying water using a flood irrigation philosophy.
Basin irrigation utilizes a flat, shallow basin surrounded by human-constructed levees. Basin irrigation works for crops not detrimentally affected by standing in water for long periods, like rice. An example of basin irrigation is Southern U.S. rice farmers. They build an earthen levee around their rice fields and, during the rice-growing season, open floodgates to allow water to move throughout the entire field.
Basin irrigation fields are typically wide, rectangular and built with a slight slope to move the water down through the field from the point of intake. But, basin irrigation can also be small and precise, such as individual basins formed around single fruit trees that are individually flooded via a hose system connected to a ditch.
Medium to fine-textured soil is best for basin irrigation.
Border irrigation is a system often used to irrigate forage crops like alfalfa, wheat, and row crops that do not tolerate standing water. It is best used on fields with moderately low to high water intake rates so the water doesn’t puddle in the field.
Border irrigation is similar to basin irrigation in that it moves across the entire field. However, in border irrigation, the area is divided into sloping borders with a ditch running along the highest elevation of the field. Fields are typically broad, rectangular, and vertically sloped from the water source. The irrigation water is allowed to drain out at the low end of the field or may be captured.
In a border irrigation system, irrigation water is released into the field from a ditch from hand-dug entry points strategically placed along the border to maximize water movement.
Furrow irrigation uses furrows between planted ridges. Fields may be of various shapes. First, the soil is prepared into vertical channels (furrows) and planting mounds. Then, water is released directly into each furrow, running down the furrow’s length and seeping into the soil at the root level.
Water is supplied to the furrows from a water pipe or ditch. Hoses or small pipes transport the water from the ditch into each furrow.
Furrow irrigation works well in annual row crop production and is best used on soils with reasonable water intake rates to prevent water from puddling on the soil surface.
History of Flood Irrigation
Flood, or surface, irrigation is thousands of years old. It was a natural progression from the earliest form of irrigation humans used – carrying water in buckets from a water source to the crop.
In regions where annual rainfall was not sufficient to support the growth of crops, humans built channels and canals to direct large amounts of water from lakes and rivers to flood their cultivated fields. The first example of irrigation canals was constructed around 5500 BC in ancient Mesopotamia (current-day Iraq).
Before the 1970s and the advent of center pivot irrigation, flood irrigation was the predominant irrigation method in the United States. Areas like the farmland surrounding Phoenix, Arizona, were transformed from desert to cropland through flood irrigation after the Roosevelt Dam was built in 1911.
Yet even with new irrigation technology, as of 2015, more than one-third of all irrigated fields in the U.S. were irrigated using flood irrigation methods. And in developing nations, flood irrigation is by far the dominant type of irrigation system.
The Pros and Cons of Flood Irrigation
With so many types of irrigation methods to choose from, it’s often best to examine the various benefits and drawbacks of each in order to make a sensible decision that won’t end up costing more than necessary or ultimately require switching to an alternative method. When thinking about flood irrigation, these are some of the benefits that should be considered:
The Most Economical Irrigation System – Flood irrigation systems are easy to build and require little to no energy resources.
Quickly Recharges Soil Moisture at the Root Zone – Flood irrigation is the best way to quickly and thoroughly recharge soil moisture levels, raise the water table and ultimately boost crop yields.
Flood Irrigation Does Not Scald Plants – Because water is applied at the root zone level, the potential of leaf scalding from water droplets – a common problem in pressurized sprinkler systems – is eliminated.
Unsustainable and Inefficient Water Use – More water may be applied than is needed to support crop growth, runoff occurs at the edges of fields, and irrigation water is lost to leaching. Nutrients may also be wasted, as they flow out of the field with water runoff.
Not Effective in Sandy Soils – While clay soils are conducive to flood irrigation systems, the irrigation water soaks in too quickly in sandy soils, leaching much of the water away before plant roots can utilize it.
Land Needs to Be Graded – Fields that are too steep or too flat will need grading work to utilize a flood irrigation system.
Methods for Making Flood Irrigation More Sustainable – Even though flood irrigation techniques are ancient, new technology, access to equipment and tools and a better understanding of soil structure have led to new ways of managing flood irrigation systems.
Leveling of Fields – Farmers use leveling equipment to make sure nothing impedes water flow through a field such as a small hill. To scrape a field flat, farmers may even employ high-tech leveling equipment, such as laser beams.
Surge Irrigation – Surge irrigation is a strategy of releasing water at intervals to reduce unwanted runoff and give the water more time to soak into the soil.
Capturing and Reusing Runoff Water – Farmers build retention systems to capture runoff water and then pump it back to the front of the field and into the water source.
Field Slope and Furrow Design to Optimize Infiltration Rates – Water drains into different types of soil at different rates. For example, furrow irrigation in fast-draining (sandy) soil works best with a .5% slope grade and narrow, short furrows. Clay-based soil, on the hand, performs best in furrow irrigation with a .1% grade and wide, long furrows that encourage water penetration across a wide soil surface.
No-Till Furrows – Farmers may use no-till methods to create their furrow channels, not tilling the furrow itself. By leaving the base of the furrow untilled, cover crops stay in place, increasing water infiltration and encouraging less water runoff. Conservation tillage techniques in furrow irrigation systems reduced runoff up to 93%, increasing irrigation efficiency.
Using Farm Management Software to Manage Flood Irrigation Decisions
Whether it’s managing soil types, crops, water sources, flow rates or application of water, there are many decisions to be made when using a flood irrigation system. Keeping track of irrigation inputs and monitoring costs and results helps farmers get the best returns from a flood irrigation system or any other method of irrigation.
AGRIVI farm management software allows growers to track any irrigation activity typically performed on a field. For example, farmers can enter the amount of water used, the water source, its costs and the exact day and time when their crop irrigation occurred.
Farmers can also use AGRIVI to manage the distribution of their water across a field, which is especially useful in water allotments are in short supply. After irrigation is complete, growers can assess the cost per irrigated field, including labor hours and machinery used in the AGRIVI dashboard.
Understanding all aspects of flood irrigation and tacking irrigation activities using farm management software to monitor costs and results can help farmers analyze and improve their flood irrigation practices for the best ROI or help them analyze whether they should switch from flood irrigation to a different irrigation system.
Ready to see how AGRIVI can help you manage your flood irrigation decisions for a more sustainable, efficient and affordable system? Contact our experts for a free consultation, and find the right solution for your needs.
Flood Irrigation FAQ Section
What is Ditch Irrigation?
Ditch irrigation is another name for flood irrigation systems that access water from a ditch.
What Crops Use Flood Irrigation?
Flood irrigation is used in all types of crops, but different crops are suitable for different types of flood irrigation. For instance, basin irrigation is only ideal for crops that tolerate standing water. On the other hand, furrow irrigation is often used in annual row crops such as corn, soybeans and vegetable production.
Is Flood Irrigation Sustainable?
Flood irrigation is the least sustainable irrigation method for water use because of its low water efficiency rates. However, because flood irrigation relies upon gravity to move water, it is much more energy-efficient than other pressurized irrigation systems that require pumps.
How Efficient is Flood Irrigation?
Flood irrigation is 50 to 60% water efficient, meaning 50 to 40% of water released in a flood irrigation system is lost either to runoff or rapid soil infiltration. Flood irrigation is the least water-efficient irrigation system.
Does Flood Irrigation Use Energy?
Flood irrigation may use energy if farmers need to pump water into the source point. However, the actual irrigation process relies on gravity and does not need power. Overall, flood irrigation is the most energy-efficient irrigation method.
Is Flood Irrigation Bad for the Environment?
Flood irrigation wastes a lot of water, so it is not a sustainable irrigation choice for the environment when viewed from that perspective. However, flood irrigation is also the least energy-intensive way to irrigate crops. Also, if farmers use flood irrigation in conjunction with no-till techniques, flood irrigation can help to improve soil health and encourage carbon sequestration.