Plan to get most from farm irrigation

IrrigationNZ says a severe El Nino could mean many farmers will run short of water half way through this season.

INZ chief executive Andrew Curtis was responding to NIWA's prediction that the current El Nino pattern is on track to be "the second most intense since 1950", with soils around the country drying out fast and irrigation in full swing as temperatures rise.

Guidelines released recently by the government urged farmers to use irrigation water efficiently and plan for water restrictions as they prepared for El Nino.

MetService says the pool of abnormally warm seas centred on the equator now extends right across the Pacific Ocean from South America to Vanuatu. Sea temperatures in August across the central Pacific exceeded 2 degrees above normal. It is the strongest El Nino since 1997-98, by all indicators.

Curtis says the focus for irrigators needs to be on spreading their water allocations further this season.

"Timing is everything in a marginal season. Irrigators need to start the season well and maintain consistent performance. Inefficient irrigation now will have a huge impact on whether your irrigation volume will see you through to March.

"Irrigation scheduling is central to this, particularly now irrigators are limited in the water they have in seasonal volumes. With water meters in place, irrigating farmers should be watching closely what they are using, regularly reviewing soil moisture levels and crop requirements and applying water as efficiently as possible. Following the dry winter there's no
room for waste or poor performance as every drop of water will be needed this summer. We recommend sitting down and planning your water budgets."

Appropriate irrigation scheduling, maintaining irrigation equipment and keeping it performing to specification will minimise down-time, leakage or delivery problems, Curtis says.

"Ensuring irrigators are working as they should guarantees you're getting the best from the water you apply. Simple early-season calibration checks can save a lot of water over the season and are a no-brainer to do. Some systems may be 20-30% out and using more water than you need will shorten your irrigation budget significantly."

As the season goes on, regular maintenance will be essential, says Curtis.

"Checking pressure and sprinklers is recommended.

Tips for summer

• • • Calibrate your irrigator: knowing exactly how much water your irrigator is applying is essential for making good irrigation decisions
    • Minimise off target application: look at where your irrigation is landing
    • Identify your soil types and estimate water holding capacity, field capacity and irrigation trigger points: knowing how much water your soil can hold is the key to successful irrigation scheduling
    • Schedule your irrigation: using soil moisture sensors or soil water budgets to understand when plants need irrigation and how much to apply is essential
    • 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
    • Re-nozzle your irrigator: reducing the nozzle sizes on your irrigator is an easy way to reduce application depths and tailor applications to a restricted water supply
    • Prioritise crops or paddocks to be irrigated.

www.irrigationnz.co.nz