What is irrigation all about? How does it work?

All this week on Table Talk we are talking irrigation and are asking the question:

Are you losing valuable irrigation $$s?

But, before we get to that, a little bit about irrigation and how it works.

Irrigation has been around for as long as humans have been cultivating plants and according to the report, Sensor Networks and Agricultural Water Management, irrigated agriculture provides:

  • 40% of the world’s food
  • from 20% of the agricultural land
  • but uses 70% of all global freshwater withdrawals. 

What are the main irrigation methods?

Agriculture Victoria has a lot of great information on each of the irrigation methods, with the  four main ones used in Australia being:

  • Surface/Flood/Bordercheck

These systems divide the paddock into bays separated by parallel ridges/border checks. Water flows down the paddock’s slope as a sheet guided by ridges.  These systems are suited to orchards, vineyards, pastures and grain crops.

  • Centre-pivot/Sprinkler

A center-pivot sprinkler is a self-propelled system in which a single pipeline is supported by a row of mobile towers suspended 2 to 4 meters above the ground. Water is pumped into the central pipe and as the towers rotate slowly around the pivot point, a large circular area is irrigated.  These systems provide water to pasture or crops, generally from above the canopy.

  • Drip or trickle

These systems use small-diameter tubes placed above or below the soil’s surface. Frequent, slow applications of water are applied to the soil through small holes or emitters.  These systems are generally used in orchards, vineyards, or high-valued vegetable crops.

  • Fixed Sprinklers

This is a stationary sprinkler system in which water-supply pipelines are generally fixed (usually below the soil surface) and sprinkler nozzles are elevated above the surface.    These systems are commonly used in orchards and vineyards for frost protection and crop cooling.  These systems are also widely used on turf and in landscaping.

How efficient are we at irrigating?

The Sensor Networks and Agricultural Water Management report suggests that by applying water to our crops we are producing yields that are 2-4 times higher than rain-fed agriculture, however even supposedly efficient and well-managed irrigation systems waste up to 50% of the water applied.

This leads to the question – are our irrigation systems as efficient as they should be?  Are we losing valuable irrigation dollars and wasting some of the resource itself?

The goal of efficient irrigation is to ensure the greatest amount of water that is applied is used by the crop rather than being lost to groundwater or off the farm as drainage.

Proper irrigation management takes careful consideration and vigilant observation and we will begin to explore efficiency issues in our next blog.

Guest contributor: Krysteen McElroy