Canterbury irrigators warned to review seasonal volumes

IrrigationNZ warns Canterbury irrigators to review seasonal volumes

IrrigationNZ is warning Canterbury irrigators to employ all the methods available to stretch out water volumes as the El Nino weather pattern starts to bite home.

“Now is an ideal time for farmers to assess their consents, particularly their seasonal allocation component, to work out how much is remaining. With about half the season left, and most irrigators in Canterbury having irrigated since September, understanding your seasonal allocation volume is critical. Having a weekly irrigation schedule based on your remaining volume is a great place to start making those hard irrigation decisions from,” says IrrigationNZ Project Manager Steven Breneger.

Rainfall across Canterbury in the week prior to Christmas has eased the short term pressure of many farmers in the region. But the forecast, post-Christmas, is still a hot, dry finish to the season – a classic El Nino weather pattern, says Mr Breneger. “This is going to place renewed pressure on irrigation consents in the new year.”

Early messaging from IrrigationNZ this season was around understanding what irrigation systems were doing on the ground. Bucket tests, scheduling irrigation to soil types, and minimising watering tracks and roads were simple measures to ensure irrigation efficiency.

“Now, the emphasis needs to moves to more stringent management options that look at performance measures across the farm and look to maximise both irrigation effectiveness and overall farm production performance,” says Mr Breneger.

IrrigationNZ’s top four tips to stretch out water volumes.

1. Identify which paddocks are top performers and which aren’t. Think in terms of production and irrigation system efficiency. By determining this now, it will make the decision-making process of which paddocks to switch off first easier. Lesser water-holding capacities, fertiliser programme, new pasture, are all the factors that need to be considered in this process.
2. Look at the irrigation systems you have and decide which give you the greatest crop production for irrigation applied. This is easier on farms with multiple irrigation system types, i.e. pivots with sprayline or long laterals in the corners or pivots with less efficient end guns. Switching off the corners saves both irrigation and labour and end guns irrigation. On farms with only a single irrigation type, for example spraylines on hill country, the emphasis should be placed on paddocks that have the greatest efficiency of application, i.e. steeply sloping paddocks always have more irrigation run-off than gently undulating ones and so are less efficient.
3. Once on a reduced area, if the daytime temperatures exceed 30 degrees or daily PET is higher than average; consider switching off irrigators during the heat of the day. This will improve overall irrigation effectiveness as it reduces irrigation losses from evaporation
4. Look at herd or crop performance; feeding lesser performing cows or continuing to irrigate lower return crops increases pressure on irrigation. Early culling reduces stocking numbers or sacrificing crops assists in the process of shutting off irrigation areas on the farm.

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