Irrigation 101

Q. What are the different types of irrigation?

A. The primary type of irrigation system in Georgia is the center pivot irrigation system, with approximately 23,000 center pivots in Georgia. Drip irrigation in vegetable and orchard production, as well as solid set sprinklers and traveling guns are also irrigation systems found in Georgia.

Q. how do irrigation systems work?

A. Irrigation systems supply supplemental water to plants either by spraying/sprinkling water from above onto plants and soil (overhead irrigation); by dripping water from a tape or tube onto the soil surface adjacent to plants (drip irrigation); or by dripping water from a drip tape that is buried in the plant root zone (subsurface drip irrigation or SDI). Center pivot irrigation systems are a common type of overhead irrigation found widely in the state of Georgia for row-crop ag irrigation.

Q. how do center pivot irrigation systems work?

A. A center pivot system is essentially a large pressurized water supply pipe that mechanically moves in a circular fashion across an ag field. The main pipe is divided into “spans” which are supported by “towers” with drive motors and the pipe is anchored at the center of the circle – hence the name “center pivot” systems. The span pipes, often 14-16 feet above the soil, are fitted with sprinklers either directly in the pipe itself or suspended below the main pipe on “drop hoses” to get the sprinkler closer to the soil and plants. The sprinklers release the water that falls from above and wets the soil and supplies the plant roots. They are powered by electricity or diesel fuel.

Q. how do drip irrigation systems work?

A. With drip irrigation, water is slowly provided to the area adjacent to the roots of the plant, usually by a network of pressurized lateral lines, drip tape or tubing, and finally, drip emitters. Drip irrigation can have the drip tape or tubing on the soil surface or could be buried drip tape in the root zone (subsurface drip irrigation).

Q. how much water do crops use?

A. The amount of water crops use depends on the crop, variety, and growth stage.

Q. when should i irrigate?

A. If irrigating a plant, you would want to irrigate when the soil moisture in the plant's root zone has been used up by the plant such that there isn't enough moisture left to keep the plant growing optimally.

Q. what is the best time of day to irrigate?

A. Nighttime is the best time to irrigate to reduce water loss from evaporation.

Q. where does irrigation water come from?

A. Our irrigation water comes from the ground or from surface water. Ground water comes from aquifers. Surface water comes from lakes, rivers, ponds, streams, etc.

Q. why do we irrigate?

A. Irrigation is the best risk management tool to safeguard against unpredictable rain patterns and drought.

Q. what does it cost to irrigate?

A. Irrigation costs can vary greatly. For urban lawn, landscape or garden irrigation, the cost to irrigate is driven by the price of water provided by the local water purveyor. For ag irrigation, the source is usually not a water purveyor but is instead from a ground water or surface water source with a pump of some sort powered by electricity, diesel or LP gas. In the case of ag irrigation, the “cost” is related to the energy cost involved in pumping/moving the water from the source to the irrigation system. UGA Extension estimates the cost at $7 per acre-inch of irrigation water applied when using electricity for the pump.