What Is Irrigation?
Whenever water is artificially applied to land for agricultural purposes we call it irrigation. The most effective form of irrigation stimulates every step of the growth process from initial seedbed preparation, seed germination, growth of the root, supply and absorption of nutrients through to the quality and quantity of yield.
Why is irrigation used?
There are dozens of reasons why irrigation is used to farm crops. In general, irrigation allows primary producers to:
- grow a higher volume and quality of pastures and crops
- achieve good plant growth during times when access to water would otherwise be limited (due to a deficit in soil moisture)
- Achieve higher yields and meet market/seasonal demands during periods where rainfall is minimal
- Lengthen the growing season
- Time the start of a growing season in years where late rain would cause a late break in the season
- Provide ‘insurance’ against seasonal variability and drought
- Increase the volume of animals per hectare with tighter, more consistent pasture supply throughout the season
- Maximise benefits of fertiliser applications which require “watering in” for best results
- Increase useable land space by utilising land that would otherwise be considered too dry to farm
- Capitalise on market incentives given to primary produces for unseasonal production
- Reduce reliance on additional feeding in grazing operations due to the more reliable supply of feed grown with irrigation
There are 7 primary types of irrigation systems available on the market today
Center-Pivot Sprinkler Systems
- The center-pivot sprinkler is a self-propelled irrigation system with a single pipeline suspended 2 to 4 meters above ground and connected by a row of rotating towers. The water is distributed in a large circular area via sprinkler nozzles attached to the pipeline as the towers rotate around a pivot point. The nozzles grade from small to large, with larger nozzles on the outside of the turning circle to maintain an even spread of nutrient distribution across all nozzle points.
Hand-Move Sprinkler Systems
- Just as the name suggests, the hand move sprinkler system is manually moved to ensure full coverage of the area to be irrigated. A hand-move system is a series of lateral pipelines attached to a mainline which can be either portable or buried. The Hand-move system is most suitable for small, irregular areas requiring irrigation and is typically used for smaller crops as a tall crop makes moving the pipelines difficult. A hand-move irrigation system is the most labour intensive of all irrigation types.
Solid Set / Fixed Sprinkler Systems
- Solid set /fixed sprinkler systems are typically found in orchards and vineyards and can be installed below the ground or along a wire or some other source of support. The solid set or fixed irrigation systems typically have exposed nozzles which drip or spray nutrients to the plant leaves or to the root ball. Solid-set systems are also widely used on turf and in landscaping.
Travelling Gun Sprinkler Systems
- The travelling gun system is a large, self-propelled sprinkler system mounted on a moving trailer or wheel. The sprinkler head is fed by a flexible rubber hose. The unit travels in a lane guided by a cable. The system requires high operating pressures as the pressure is used to both force water through the sprinkler to water the ground and to propel the wheel or trailer. 100 psi not uncommon.
Side-roll wheel-move systems
- The side-roll wheel-move systems use large-diameter wheels astride a pipeline, allowing the line to be rolled as a unit to consecutive positions across the field. The side-roll wheel-move system is not suitable or all crop types as the pipe sits approximately 1 meter above the ground.
Linear or Lateral-move Systems
- The linear or lateral-move systems are similar to center-pivot systems, with the exception that the lateral line and towers move in a continuous straight path across a rectangular shaped field. Water is supplied to the linear or lateral-move system via a flexible hose attached to the system of or pressurised from a concrete-lined ditch along the field’s edge.
Low-flow Irrigation Systems (these include drip and trickle)
- The low-flow irrigation systems (including drip and trickle) use narrow-diameter tubes located above or below the soil’s surface. The low-flow system is typically used in orchards, vineyards, or high-valued vegetable crops. Water is supplied frequently but slowly to the soil through small holes or emitters. The emitters receive the nutrient water via a network of main, submain, and lateral lines. The low-flow irrigation system is highly efficient due to the water being dispensed directly to the root zone, which avoids runoff and minimises water loss through evaporation.
The best-fit irrigation system for your operation requires knowledge of equipment, system design, plant species, growth stage, root structure, soil composition, and land formation. Choose an irrigation system that will boost plant growth while minimising associated problems such as salt imbalances, leaf burns, soil erosion, and water loss from evaporation, wind drift, and run-off.