4.1.4.3 - How much should I apply, or how long do I run water onto the bay for?

Return to Main Menu | Return to Step 4 | Return to Step 4.1 | Return to Step 4.1.4 | Next Step

Irrigation management should aim for an even distribution of the correct depth of water over the bay with minimal runoff at the bottom end. Typically for SIR soils, about 40 to 50 mm of water is applied.

It is common practice to cut off flows when the water front has reached half to two thirds of the length of the bay. Cutting off too soon results in water not reaching the end of the bay; too late results in excessive runoff and waterlogging. The optimum cut-off point will vary with the density of pasture on the bay, and the soil moisture deficit at the time of irrigation (dryness) which largely determines how much water the soil takes up.

With a well designed bay on suitable soils, the required amount of water should be applied in 2 to 4 hours. However, up to 6 hours is generally accepted as reasonable. The time required to apply the required amount of water can be varied by varying the flow rate.

Irrigating “short” as a means of conserving water is generally not recommended, unless severe water shortages are experienced. Reducing the number of bays and full irrigation of these bays is more productive. However, if area at the bottom of the bays is not producing well (say through waterlogging), or there is no drainage reuse system, watering short can be a water saving compromise.