Irrigation New Zealand

Fertigation is the term used when using an irrigation system to apply fertilisers. Fertigation can be a significant advantage over conventional broadcast methods as timing, quantity and accuracy of application can be greatly improved. Generally an irrigation system with fertigation must be managed differently than conventional irrigation.

2019-2021: FERTIGATION – A NEW TOOL FOR NUTRIENT MANAGEMENT?

In 2019 Irrigation New Zealand received a grant from the Sustainable Farming Fund to further research the potential benefits of fertigation. Field trials were conducted over two seasons 2019/2020 and 2020/2021 with the aim to further understand whether the use of liquid/dissolved urea through fertigation could increase N use efficiency and pasture production, quality and clover content over traditional solid urea. The project outcomes hope to provide irrigators with clear information for successful fertigation, including providing advice on how to successfully design, install, and manage fertigation systems.

As part of the project, the Fertigation resource book was updated in 2021, and can be found on the right hand side of this page (available to members only).

This document will help irrigators that are wanting to install or operate with fertigation. 

Part One of the guidance document covers the Good Practice recommendations that will help irrigating farmers identify:

  • Considerations for adopting fertigation
  • Long term benefits of fertigation
  • Safe management practices for fertigation
  • Fertiliser types and mixing considerations
  • Operating issues of a fertigation system

Ensuring the uniformity distribution of the water application system is a critical first point before venturing into fertigation.  A system performance assessment is recommended.

Part Two of the guidance covers developing a fertigation system. This is information for system designers to understand:

  • Fertigation injection systems
  • Backflow prevention systems
  • Irrigation system design considerations
  • Interlocking fertigation injection devices
  • Holding tanks design

It explains the advantages and disadvantages of different fertigation system types and their componentry. Key operating considerations, including how to calculate application rates are also covered. 

BACKFLOW PREVENTION

The Fertigation guide now incorporates the previous backflow prevention recommendations into one comprehensive document, that includes information to help designers looking at the options for fertigation.

The guidelines do not amend or replace other industry performance indicators, guidelines, codes of practice or standards. Designers and installers should interpret the guideline according to the requirements of individual properties and owners. All decisions made must also comply with statutes, regulations, and other legal requirements and industry standards.

Environment Canterbury have put together a guide to provide irrigators in the Canterbury region with information on chemigation valves for backflow prevention: Canterbury Backflow prevention Guidelines

You can also visit this page on their website: click here

In addition to updating the Fertigation guidance, the project also achieved other milestones:

  • Literature review and key issues identified
  • Year one fertigation field trials complete as part of master’s thesis “Can Fertigation Increase Nitrogen Use Efficiency in New Zealand Dairy Pastures?” 
  • Summary of year 1 findings published
  • Year two trials completed in April 2021, findings published
  • Summary of year 2 findings published
  • Two cases studies of farmers implementing fertigation have been completed
  • New fertigation guidance document launched December 2021

Information and reports produced as part of the project are available here:

Fertigation in New Zealand Literature Review and Key Issues Report

Fertigation Case Study: Andrew Paterson, Otago

Fertigation Case Study: Cam Henderson, Canterbury

T. Ley Masters Thesis, Can Fertigation Increase Nitrogen Use Efficiency in NZ Dairy Pastures?

Year 1 Summary Results Report

Year 2 Field Trial Report

Year 2 Summary Results Report

With thanks to the Ministry of Primary Industries and our project partners Ballance Agri-nutrients, Molloy Agriculture Ltd,  Pamu Farms of New Zealand, Landcare Research and Fertigation Systems.