IrrigationNZ says the recent Environment Aotearoa report highlights the need for farmers and growers to continue work underway to: improve practices on-farm and upskill farmers; invest in cutting edge technology; and implement Farm Environment Plans to change the way water is used for production.
“In partnership with national and regional government, it’s essential we continue to research, trial and adopt new practices and technology,” says IrigationNZ Chief Executive Elizabeth Soal.
“It is critical that we recognise that water is a precious resource which is essential for primary production and regional resilience in the face of climate change and that we use it in a way that is environmentally responsible.”
“This means continuing to improve water use efficiency through proper training, new farming methods and the use of modern infrastructure.”
IrrigationNZ says it is encouraging that since the last Environment Aotearoa report was released in 2015, nitrogen trends are improving. By 2018 more sites had improving rather than worsening trends with nitrate-nitrogen and ammoniacal nitrogen improving at 58% and 75% of sites, respectively. In the 2015 report (page 64) 60% of monitored sites showed increasing total nitrogen levels.
“The adoption of good farming practices in recent years is already having an impact on water quality with many water quality indicators showing improvement in the most recent LAWA dataset,” adds Ms Soal.
Excluding hydroelectric use – the largest consented water use in New Zealand – the amount of water consented to be abstracted is equivalent to 2% of New Zealand’s total annual rainfall. Half of this total (equivalent to 1% of total rainfall) can be used for irrigation.
“Irrigating farmers and growers understand that they have a range of environmental responsibilities. In fact, irrigation schemes are leading the way on the adoption of Farm Environment Plans which require that farmers identify environmental risks and take steps to address these. Schemes also employ environmental managers to proactively advise farmers on good environmental practices and all schemes must adhere to new regional council plans and consent rules.”
In recent years it has become mandatory for regional councils to set minimum flow levels for rivers which prevent water from being taken from rivers below the level set to support ecosystems.
There has also been huge investment made to modernise irrigation systems and infrastructure to become more water efficient. Since 2011, $1.7 billion has been spent by farmers and irrigation schemes on modernising systems. The 2017 Agricultural Production Census shows that over 90% of New Zealand’s irrigated land area uses spray or drip irrigation which is the most efficient form of irrigation. The amount of surface irrigation used in New Zealand fell by over 50 percent from 2012 to 2017.
“Over recent decades the design of irrigation infrastructure has been changing to achieve better environmental outcomes. For example schemes like the Waimea Community Dam and a number of other dams store water and release this into rivers in times of low flows, and well as storing water for use by farmers over the summer,” says Elizabeth Soal.
“Around 7% of New Zealand’s agricultural land is currently irrigated and irrigation is estimated to contribute over $5 billion to our economy. Climate change is predicted to result in more frequent and severe droughts and the importance of irrigation will only grow in the future. We will continue to need irrigation in order for food to remain affordable in a more changeable climate,” says Ms Soal.
 By comparison, worldwide the Food and Agriculture Organization of the United Nations estimates that 86% of irrigated land uses surface irrigation which is the least efficient form of irrigation and 14% of land uses spray or drip irrigation.