The Importance of Evapotranspiration in Irrigation Farming

One of the more complicated concepts involved in the programming of farm irrigation systems is evapotranspiration and how it affects irrigation amounts.

It is a variable that affects irrigation system management in many ways, so must be understood to make accurate irrigation calculations.

Correctly measured, regularly monitoring evapotranspiration will improve crop yield and prevent plant loss, all while using the least amount of water necessary to do so.

What is Evapotranspiration?

Evapotranspiration or ET is a combination of two natural processes: evaporation and transpiration.

Evaporation is the process of water leaving the soil and plant surfaces to be absorbed into the air while transpiration is the process of plants losing water through their stomata into the air.

Since these are basically the same effect happening in two different ways, they are calculated as evapotranspiration or the amount of water absorbed into the atmosphere from plants and soil.

It is a key factor in many crop and soil management details such as plant growth and physiology, hydrologic cycle, microclimate and surface interactions, drainage, and all relationships between the soil, plants, water, and the atmosphere.

Why Is Calculating Evapotranspiration So Important?

When programming farm irrigation systems, every drop of water, and whether it actually reaches the plant roots, counts.

Since evapotranspiration constitutes a certain amount of water that does not reach the roots and is instead lost back to the atmosphere, this loss must be carefully estimated and then configured into the irrigation system programming.

ET can be measured using some of the more advanced irrigation system technology that track weather, soil, and atmospheric conditions.

Doing so is one of the ways that farmers today can reduce plant loss due to not enough irrigation while also reducing water wastage due to over-irrigating.

The Value of Programmable Farm Irrigation Systems

A critical part of effective crop management for getting the highest yield is making sure plants get the water they need, day in and day out, regardless of the weather.

Programming farm irrigation systems so they are used most efficiently is complex, but with the newer technology now available it is becoming easier every day.

Irrigation systems that can measure and calculate something as seemingly insignificant as evapotranspiration can make a huge difference in crop yield and farm success.

With the ability to track evaporation and transpiration by the day and estimate the need for more or less irrigation, farmers can grow more efficiently. Irrigators offering this type of technology can now be found at farm irrigation system dealers everywhere.

Irrigation is Advantageous on Many Counts

If you've ever driven or flown across the United States, then you've probably noticed large fields with sprinklers.

From the air, these fields can look like large circles or half circles.

What you've seen is farm irrigation.

What Is The Purpose of Farm Irrigation?

Farm irrigation is what farmers and others do to bring water to crops.

This type of irrigation is more common in the south central and western areas, where rainfall can be unpredictable and sporadic.

Irrigation allows farmers growing agricultural crops to provide a specific amount of water on schedule, which results in a healthy crop yield.

Irrigation Benefits

There are actually a number of benefits to farm irrigation, including landscaping, protection from frost, the prevention of soil compaction, sewage dispersal, suppression of dust and even mining.

Crops that are typically irrigated include sunflowers, soybeans, edible beans like navy and great northern beans, corn and alfalfa.

Types of Irrigation

Types of irrigation differ depending on the needs of each crop.

For example, irrigation for alfalfa may be an overhead sprinkler system on a center pivot or it may be a small canal with drain tubes that spill water over the ground.

Most people are more familiar with drip irrigation, which is where a small nozzle drips into the root region of each plant.

This type of irrigation is used typically for homeowners' watering needs, since it requires a specific dripper nozzle for each plant.

Types of Irrigation - Flood

Flood or surface irrigation is used when a stream or canal that has been dammed is opened, allowing the water to flood a given field or area.

The field is usually sloped slightly to allow the water to work its way to the bottom end so that all plants can receive moisture.

Rice fields are generally watered with flood irrigation, as well as cranberries, wild rice and sometimes alfalfa.

This type of irrigation is the oldest on record and has been employed for centuries.

One modified type of flood irrigation has become widespread in Nebraska and southern Wyoming.

Plastic PVC tubes of large dimension are placed along one edge of a crop as a continuous pipe and shallow trenches are dug between each plant row.

The PVC tubes have half-inch holes drilled every four to six inches and is attached to a water source.

The water is then allowed to drain out the holes and down the trenches between the plant rows, soaking the roots.

This type of irrigation is typically used with corn production.

Types of Irrigation - Sprinkler

Another common type of farm irrigation is known as sprinkler irrigation.

This is done with a giant overhead sprinkler head that is fed from a hose; picture a high-pressure "Rain Bird" type sprinkler, just on a colossal scale.

These sprinkler irrigation systems are used for small field applications like a baseball field, football field, cemetery and so on.

The sprinkler head, sometimes called a "gun," can be moved to any convenient spot.

This type of irrigation is considered to be older technology.

Types of Irrigation – Center Pivot

Today's farm irrigation is known more by the center pivot.

The center of the pivot is a large hub from where the water is pumped with one or two arms extending the length of the field, held up by wheeled supports that move slowly.

These wheeled hubs will travel in a circle around the hub, using drop sprinklers to provide water to growing crops just a few feet below.

If the length or size of the field prevents traveling in a full circle, the center pivot can travel a quarter circle, a half circle, or some designated degree of a circle.

Center pivots are probably the most commonly known irrigation process, and are used to water corn, sunflowers, soybeans, edible beans, alfalfa and more.

In Summary

Today's farm irrigation is much more complex and involved than simply spraying a plant with a hose.

This technology allows agricultural crops to be grown in a wide variety of areas and climates.