Nutrient loss under the spotlight
New Zealand’s shift from a pasture-based model to high feed-input dairy farms will come under the microscope in a joint
research project involving Ballance Agri-Nutrients, AgResearch, DairyNZ and Tatua, in partnership with the Government’s
Sustainable Farming Fund initiative.
The two year project, led by AgResearch’s Dr Stewart Ledgard, will use case study farms varying in intensity of feed use
to examine effects of their system changes over the last decade on emissions, production and profit as well as testing
options for improving their sustainability.
“Locally there is strong interest in understanding implications for water quality of dairy intensification through
increased use of supplementary feeds and how effects can be minimised, while internationally there is a desire for food
products to be produced with efficient use of resources and reduced wider environmental impacts”, says Dr Stewart
“This project will apply a mix of regional and international market related methods.”
Ballance Science Extension Manager Ian Tarbotton says the industry recognises there has been an increase in high
feed-input farms in the past 10 years, but there is no holistic approach to determine when the higher-input system has
an adverse impact on the farm business and beyond.
“This project is leading edge as it will evaluate the whole farming system, accounting for all land and brought-in feed
through to water quality and energy use. We will be able to help farmers with nutrient use efficiency and farm system
monitoring through increased farmer awareness of the hot-spots for nutrient losses.”
Mr Tarbotton says that over the last decade dairying has changed with larger average herd sizes, higher milk production
and stocking rates and a rise in both land prices and farm debt. While different studies had been done, few have looked
at the economic and wider environmental impacts or taken a whole-of-farm view.
“Future farm systems will have different monitoring, metrics and thresholds for on-farm decision making. New indices
will come from this research such as water use per kilograms of milk solids or nitrogen leached by profit level. Farmers
will be able to rely on better evidence-based scientific information to drive their farm decisions rather than
defaulting to routine decision making. Farmers need insight into implications of environmental policies on water and
nutrient loss to ensure their increase in feed doesn’t push them outside these limits,” he says.
The project commenced in July with a group of more than 20 high feed-input dairy farmers in the Tatuanui area of central