Irrigation New Zealand

Drought Advice

With climate predictions pointing towards long hot and dry springs and summers, irrigators need to put in place management strategies to maximise their water allocations. Below are some tips that improve efficiency and increase the longevity of allocations.

1. Performance evaluation of your irrigato
r – Knowing exactly how much water and how accurately your irrigator is applying water is essential for making good irrigation decisions. A simple bucket test can accurately assess your irrigator performance. Understanding your system capacity and return interval is also critical. While the Bucket Test app is a great way to get a rough indication of performance, we recommend getting a qualified performance assessor to conduct a full evaluation that includes observations and analysis of other critical performance measures in addition to a bucket test result.

2. Minimise off-target application
– Look at where your irrigation is landing. Watering tracks, laneways, and other non-productive ground waste water. Off-target irrigation, such as watering public roads, is prohibited in many districts. It’s also not a good look during a drought.

3. Identify your soil types and know your water holding capacity, field capacity, and irrigation trigger points
– Knowing how much water your soil can hold is essential to successful irrigation scheduling. Knowing the locations of your different soil types within your irrigation area is also a powerful management tool.

4. Schedule your irrigation
– using soil moisture sensors or soil water budgets to understand when plants need irrigation and how much to apply is essential. For soil moisture sensors you need to measure and record all irrigation and rainfall events. For water budgets, you also need to record daily plant water use (evapotranspiration). Make sure the equipment is operating correctly and any trace or trigger lines on your data report are correctly set up for your season.

5. Adopt deficit irrigation practices
– Deficit irrigation is a scheduling practice that keeps the soil water above the irrigation trigger point but does not fully recharge the soil to field capacity. This allows any rainfall, particularly during the shoulders of the irrigation season, to be taken advantage of, minimising drainage or surface flow losses from irrigation whilst maximising both your production and water allocations.

6. Re-nozzle your irrigator
– Reducing the nozzle sizes on your irrigator is one way to reduce application depths and tailor applications to a restricted water supply. However, this method must be done with input from your irrigation service company to avoid damage or inefficiency within the irrigation system, especially putting pumps and control valves at risk of over pressurisation.

7. Prioritise crops or paddocks to be irrigated
– By targeting irrigation to areas of higher production or higher value crops maximises your profitability during drought restrictions. Lesser production areas or lower values crops will have yield losses as these areas will suffer moisture stress.

8. Reduce your irrigation area
– Reducing your total irrigation area increases the amount of water available per hectare and may help to get the best from a restricted water supply. Targeting water to more efficient irrigation systems or soil types increases water use efficiency. This may not be easily achieved under some irrigation system types and may require some additional advice to avoid concentrating flows that exceed the infiltration and water-holding capacity of soils. More advanced irrigation system types, (e.g., VRI on pivots/linear), can target complex irrigation patterns within a single irrigation area.