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Irrigation systems require suitable application depth, rate, and return periods to meet soil, plant, and climate needs. This page encourages evaluating your system against its design specifications to find potential improvements. A detailed evaluation can be completed independently using farmer-focused guidelines, or by an irrigation consultant. The 'bucket test' is a highly recommended annual evaluation method for checking the application depth, rate, and uniformity of your irrigation system. Various tools, like the 'Check-it bucket test' app from IrrigationNZ or the 'DIY irrigation evaluation guide', are available to help with this process.
An irrigation system that has an appropriate application depth, rate and return period to match the soil characteristics, plant demands and climate needs will be more able to maintain soil moisture levels.
An evaluation requires knowing what the system is specified or designed to do, and checking it is performing to that level. It will also identify areas for improvement.
A detailed system evaluation can be completed by an irrigation consultant or a farmer can carry out their own, using instructions and guidelines developed for farmers.
The table below identifies areas where water losses occur in an irrigation system, and typical amounts. The best ways to improve water use efficiency are to improve how evenly the water is applied, and to optimise the application rate and depth of your system.
|Where water loss occurs||Range||Typical|
Uneven application (non-uniform distribution)
|Excessive application depth||0-50%||10%|
|Losses from open races||0-30%||10%|
|Blown away by wind||0-20%||<5%|
|Evaporation in the air||0-10%||<3%|
|Water non-target areas||0-5%||<2%|
|Interception by plants||0-3%||<2%|
A bucket test is a great way to evaluate your system. It should be done at least once a year to ensure that the system is in top shape.
Carrying out a ‘bucket test’ will help determine the application depth, rate and how uniformly water is being applied during an irrigation event. The ‘bucket test’ method is based on collecting irrigation water strategically placed buckets and measuring water is collected over a certain period of time.
There are a number of different ways that you can complete a bucket test on your irrigation system.
The most common signs of poor performance are:
The most common reasons for under-performance are:
Options for making improvement range from adding to the existing system (e.g. including another rotary boom) in order to reduce the return period and/or the application depth per run, through to a total change in irrigation type e.g. border dyke to spray irrigation.
It is important to remember that changing or improving irrigation system capability should not be done in isolation, but incorporated with soil moisture monitoring and continual performance evaluation to achieve maximum improvements in irrigation efficiency.
Firstly, it is important to:
If simple problems are encountered, you can fix them yourself. However, the system supplier should be the usual first port of call for anything more complex.
Call the irrigation system supplier when:
Sometimes you need to call in a third-party irrigation expert.
Ask for outside advice when: