Dairy Effluent Calibrations

Project title

SFF 07-016 Canterbury Dairy Effluent Application Efficiency

Project Funding

MAF Sustainable Farming Fund Dairy New Zealand

Project Status

Completed 2009


Funding from Dairy New Zealand and the Sustainable Farming Fund enabled us to undertake a small review of on farm performance of effluent irrigation systems on a range of farms in Canterbury, Hawke's Bay and Waikato. A series of owner/manager interviews was conducted in parallel by Debbie Care of Dairy NZ. This and our on-farm evaluations provided insight into the current state of equipment performance and staff knowledge of effluent application. Effluent is a useful input to pasture production if applied uniformly at correct rates. Excessive application and low distribution uniformity increase nitrate leaching risk. Uniformity will be considered by regulators in the future. Current practice performance benchmarks are important. A wide range of effluents, soils, equipment and climates make management complex. Farmers do not know how particular effluent irrigation system types actually perform, how to maximise benefits from effluent application, or how to minimise any environmental impacts of the effluent.


We identified a range of farms across Canterbury, Hawke’s Bay and Waikato on which different types of effluent irrigators were used. We tested the machines using an adaptation of the Irrigation Evaluation Code of Practice Protocols (SFF 02-051) and made recommendations for improvement. We also developed and tested farmer 'do-it-yourself ' system calibration guidelines and worksheets, adding to our IRRIG8Quick series. These were trialed in the Toenepi Catchment study area. Download IRRIG8Quick Effluent Calibration guidelines here>

Main findings

The system performance levels were variable as a result of a range of factors:
  • Poor equipment design (travelling irrigator design giving low uniformity and high application depths and rates) provided limitations
  • Poor system design resulted in inadequate pressure and frequent nozzle blockage, further limiting performance
  • Operator errors such as incorrect machine speed settings resulted in excessive application depths

What could farmers do?

In some cases simple changes such as increasing irrigator speed would reduce excessive applied depths, and fixing nozzles or changing run spacing could improve application uniformity. In a number of cases the system pressure was inadequate but was not easily remedied. At least two systems have been replaced so pressure problems could be corrected. Several other farmers indicated that the results were unsatisfactory and a total system replacement was intended. The time frame for replacement was not clear because they did not want to spend money fixing a system they saw as redundant. Farmers recognise the nutrient value in effluent and are seeking to retain it for production. But without assurance the next system will be any better than the last, they are understandably slow to invest.

Other industry initiatives

This project highlighted that the industry, farmers and system manufacturers, does not have performance measures against which to assess system performance. Both agreed performance indicators and acceptable agreed methods to assess performance are lacking. Their absence means even equipment suppliers and system designers have little knowledge of minimum standards to meet. A major industry initiatve to fill this gap has been underway. A new Code of Practice for Design and Design Standards are in the offing. For the first time, agreed and justified performance targets will be available. Not all staff on all farms have the necessary knowledge to operate even existing systems correctly. Dairy NZ, together with the Agriculture Industry Training Organisation, has developed Unit Standards and training  courses for effluent system operators. The aim is to make all staff fully aware of the importance of correct operation. A further initiative will see material launched for managers of effluent systems - when to apply and how much, to maximise nutrient utilisation and protect the environment.

Download system reports

On-farm testing existing systems

Travelling irrigators

Pivot based effluent spreaders

Long lateral effluent irrigation

Stationary Gun irrigation

Clean water controlled testing of new travelling irrigators

Leave a Reply

Your email address will not be published. Required fields are marked *