Farm advice: Fertigation guide could help reduce nutrient losses

IrrigationNZ recently released a new guide to using fertigation, which could help change how we use irrigators in the future

Fertigation is the application of nutrients via irrigators and is increasingly being adopted as a good environmental practice overseas.

By applying nutrients through an irrigator, small quantities of fertiliser can be applied at a time, resulting in more uptake of nutrients by plants and less leaching into groundwater. 

Fertigation results in more uptake of nutrients by plants and less leaching into groundwater

The guide was developed following a Fertigation Masterclass we held last year to discuss fertigation best practice.

IrrigationNZ also organised a study tour to Nebraska in September for 25 of our members to look at new irrigation technology and practices. Our tour group included farmers, irrigation designers, farm consultants, and irrigation scheme representatives.

Fertigation was the most common way they applied fertiliser on irrigated farms in Nebraska. It saved time on farms and allowed more precise fertiliser application and also reduced risk.

One story we heard about was from a corn farmer who paid off the cost of a fertigation system in one season when they had heavy rain. This meant he lost his crops but he hadn’t applied fertiliser yet so he didn’t waste his fertiliser too.

Fertiliser is one of their biggest expenses on farm. Using fertigation is seen as a way to limit the movement of nutrients beneath the root zone of the crop and we saw some research indicating that plant uptake of nutrients through fertigation is very high, so using fertigation could potentially reduce nutrient leaching significantly.

The new guide covers how to use fertigation and it’s targeted at farmers and is also helpful for service industry representatives who need to understand how to design and use fertigation systems.

It explains the terminology and options available and the pros and cons of these as well as some pitfalls to avoid. Fertigation can be used to apply a range of nutrients, however, some of the nutrients shouldn’t be mixed and applied in one dose so there is advice on that.

Currently, fertigation is used in many places worldwide and is resulting in nutrient savings but it’s rarely used New Zealand except in horticulture. Everything else has changed on farms over the past few generations but we are still using a 60-year application method for fertiliser.

Pamu, IrrigationNZ, and Ballance Agri-Nutrients are working on a project to test the use of fertigation and measure nutrient use and losses, which will provide some data for Overseer. Although the project has only started running this summer, it’s already showing that overall fertiliser use has been reduced while pasture production remains good. Within a few years, the cost of installing the fertigation system will be paid off, and Pamu expects to save costs as a result of the change.

As part of the project, a Master’s student will be engaged and supervised by Lincoln University. They will calculate nutrient losses from the fertigation trial over the next two summers.

There are also a handful of farmers out there – including some from our tour – who are already steaming ahead with their own plans to use fertigation. So it’s all change on the farm for the better.

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