El Niño prompts call for Canterbury & Otago farmers to plan ahead for irrigation needs

Canterbury and Otago farmers and growers are being encouraged to check their irrigation systems and water-use plans now, as El Niño increases the likelihood of drier conditions across eastern parts of New Zealand.

Earth Sciences New Zealand has confirmed that El Niño conditions have developed in the tropical Pacific and are expected to strongly influence New Zealand’s weather into 2027.

Irricon principal environmental consultant Sarah Rickard says the outlook is a timely reminder for farmers and growers to make sure their irrigation systems are ready before seasonal demand increases.

“Dry conditions were already evident across parts of Canterbury heading into winter, and we had reached meteorological drought by the middle of June,” Sarah says.

“Now that we are in July, with El Niño declared and the possibility of a drier spring for eastern areas, it is worth checking that your irrigation equipment, soil moisture monitoring and water-use planning are all working as they should.

“These checks are always important, but they become even more valuable when water availability or consented volumes are limited.”

Understand your consent conditions

Sarah says farmers operating under annual water volumes or restrictive return-period conditions need to pay close attention to how they manage their use and allocation.

“When conditions become dry, there can be pressure to irrigate early and often,” she says.

“However, using too much of your annual allocation at the beginning of the season could leave you short of water later.”

Farmers should understand their annual and seasonal consented volumes, any daily or return-period restrictions, minimum flow restrictions, how quickly their allocation is being used and whether water-use records and measuring equipment are accurate.

Test application depth and uniformity

Irrigators should be tested to confirm they are applying water evenly and at the expected depth.

“An irrigator can appear to be operating normally while still delivering too much water in some places and not enough in others,” Sarah says.

Uneven application may result from pressure issues, worn or blocked nozzles, incorrect sprinkler setup, spacing problems or other maintenance requirements.

“If water is not being applied evenly, some areas may become too wet while others remain moisture-stressed,” she says.

“You may also use a significant amount of your consented allocation without getting the result you need.”

Testing equipment and maintenance checks during winter gives farmers time to identify and address any problems before irrigation systems are operating regularly.

Check soil moisture monitoring

Irricon environmental consultant Jane Robb, who specialises in soil moisture monitoring, says probes can provide valuable information about when to irrigate and how much water to apply, but only when they are installed, configured and interpreted correctly.

“Make sure your probes are positioned in the right soil types for the area you are irrigating, are working properly and have appropriate trigger points for your soils and crops,” Jane says.

“It is also important that the people making irrigation decisions understand what the readings are telling them.”

Farmers should check that probes are installed at appropriate depths, and trigger points suit the soil type, crop and root zone.

The data should be reviewed regularly, ideally ahead of each irrigation season, and used to guide irrigation decisions before plants become moisture-stressed.

Alongside understanding consent limits and checking irrigator performance, soil moisture monitoring should form an important part of every farm’s preparation for the season ahead.

Five irrigation checks to complete now

1. Review water allocations and consent limits and consider how water will be prioritised if dry conditions continue.

2. Test irrigator performance for application depth, pressure and uniformity.

3. Complete maintenance early, including replacing worn or blocked nozzles.

4.    Check soil moisture probes are installed correctly, provide reliably data and are positioned in the correct soil type.

5. Review irrigation trigger points to make sure they suit the soil type, crop and root zone.

Sarah says El Niño does not guarantee drought, but it reinforces the importance of preparation.

“None of us knows exactly how the season will unfold, but farmers can control how ready their systems are,” she says.

“Finding a problem now is much better than discovering it when irrigation demand is high and every millimetre of water counts.”

Sarah Rickard is principal environmental consultant Irricon