About 270 delegates gathered for the three-day workshop, which focused this year on nutrient management for the farm, catchment and community.
In his opening address, Professor Mike Hedley, director of the FLRC, said the national water reforms under way will be a key vehicle for determining nutrient management in the short- to medium- term.
“It plans New Zealand’s pathway for the next few years of how we introduce freshwater reforms by regional councils getting together with their communities and setting limits. Those communities will form committees that work with catchments to try to manage their water quality.”
The range of presentation topics spread from the more technical, such as the development of a cost-effective technique to measure denitrification (the part of the nitrogen cycle converting greenhouse gas nitrous oxide to harmless dinitrogen) in the lab, through to the wider perspective, such as the papers focusing on how nutrient management strategies were implemented in the Lake Rerewhakaaitu catchment.
Environmental modelling at the farm, catchment and regional scale was a recurring theme. Nutrient budgeting model Overseer, owned by the Ministry for Primary Industries, the Fertiliser Association of NZ and AgResearch, came under scrutiny.
Overseer general manager Caroline Read outlined the evolutionary nature of the model, citing the regulatory environment, changing farming practices, technological advancements and improving datasets as drivers of that evolution.
“The expanding use in the [environmental] policy environment does provide quite a few challenges for the owners of Overseer in maintaining the model.”
“In the short-term, a stakeholder advisory group will develop the strategic direction of Overseer and provide external technical, industry-wide linkages. One of the most common criticisms concerning Overseer is the uncertainties in the output values, an increasing concern in the face of its adoption as a regulatory tool by regional councils,” Read said.
Recently a set of best practice data input standards has been developed by a technical advisory group. In a presentation given by advisory group member Ants Roberts, the chief scientific officer with Ravensdown said the uncertainties undermined farmer confidence in the model.
“The guidelines were not developed to teach people how to use Overseer,” he said.
“They merely tell you how to choose the inputs to go into Overseer – it’s not intended to be an auditing system in terms of the nutrient budgets that are produced.”
