Research shows farmers are using water more efficiently in Canterbury

Farmers have installed more efficient irrigation systems throughout Canterbury over the past decade or so, according to two new reports prepared by Aqualinc.

The Canterbury Detailed Irrigation Area Mapping reports, commissioned by Environment Canterbury, analysed irrigation areas and irrigation application types across the region from 2002 until early 2015.

“There has been a significant move by farmers over the past 10 years to convert to more efficient spray irrigation systems," said Don Chittock, Programme Manager for the Canterbury Water Management Strategy at Environment Canterbury.

Over the five years, from mid-2010 to 2015, the amount of efficient spray irrigation went from 371,000ha to 479,000ha, an increase of 29 per cent. Total irrigation went from 425,000ha to 507,000ha (19 per cent).

Over the same period there was a 48 per cent reduction in the amount of surface (borderdyke) irrigation from 54,000ha to 28,000ha.

“Many farms are changing from the inefficient borderdyke system to centre pivot spray irrigation, which uses about half as much water to the same effect.”

The reports also estimate around 60% of irrigation is happening at 80% efficiency or more (which meets the target set for industry agreed Good Management Practice).

“A key benefit of using the more efficient spray irrigation systems is lower nitrate leaching losses to groundwater.

“Farmers are being asked to measure and reduce nitrate losses to improve water quality. By moving to more efficient irrigation, farmers are achieving industry agreed Good Management Practice.

“We are working with industry to encourage farmers to adopt industry agreed Good Management Practices which promote the efficient use of both water and nutrients.

“Improved irrigation efficiency is a key contributor to improved nutrient management outcomes, as well as providing production and profitability benefits.”

Key points

  • From May 2010 to January 2015 the total irrigated area in Canterbury rose from 425,000 ha to 507,000 ha (+82,000 ha or 19%)
  • During this time surface irrigation reduced from 54,000 ha to 28,000 ha (from 13% of total area to 5.5%)
  • Aqualinc estimate that approximately 55-60% of the area irrigated in Canterbury in 2015 achieved an application efficiency of 80% or higher. (A 2015 CWMS Target was for water efficiency was for 60% of water used for application to be as best practice)
  • The term “irrigated area” means the area actually irrigated for productive gain, not the consented area. For example, if a lifestyle block has a water permit to irrigate 4 hectares, but only irrigates 0.5 hectares in practice, then their irrigated area is 0.5 ha.

Background information

The Aqualinc reports provide an overview of irrigated areas and irrigation application types across Canterbury as at January 2015.

Aqualinc has used remote sensing techniques (aerial photographs, satellite multi-spectral analysis) together with Environment Canterbury’s Resource Consent database, to accurately map irrigation area at a farm scale

Disclaimer

The mapping data includes information originally commissioned by Amuri Irrigation, Morven Glenavy Ikawai Irrigation, Ashburton Lyndhurst Irrigation, Barhill Chertsey Irrigation, and DairyNZ (Hinds nutrient zone). This was made available to Environment Canterbury to enable a consistent approach to irrigated area mapping.