New farm management tool for environmental protection

Collaboration is all important when it comes to protecting New Zealand’s rivers and streams.

Professor Richard McDowell leads AgResearch’s contribution to a multi-agency programme

to give farmers better tools to understand and manage the environmental impacts of their farms more effectively.

The Clean Water, Productive Land programme includes scientists from the National Institute of Water and Atmospheric Research (NIWA), Landcare Research, Environmental Science Research, Government agencies, regional councils and the private sector. The $3.3 million per annum programme is made up of a number of different projects.

One project, supported by Ballance Agri-Nutrients, is developing a prototype spatial add-on to the nutrient budgeting software, OVERSEER® (owned by AgResearch, the Ministry for Primary Industries and The Fertiliser Association of New Zealand (Inc), previously known as Fert Research) with the aim of providing farmers with the tools to understand where losses are occurring on their farms and the appropriate management responses to reduce them.

The software prototype includes a facility to set a water quality objective (e.g. percent decrease in phosphorus loss) and see the effect (percent decrease and cost) at paddock or farm scale of different mitigation techniques such as fertiliser and irrigation strategies or effluent application methods and rates.

Models developed within the wider programme allow the best science to be joined with the best available databases (e.g. soil types and land contours) and knowledge of farm management. Farmers will be able to assess the likely cause and effect relationships on their own farm system and develop future scenarios based on different mitigation techniques.

“The major losses of water quality contaminants come from a minority of a paddock, farm or catchment’s area,” says Prof McDowell.

“Our ability to focus on the small areas that contribute most of the losses enables mitigation strategies to be targeted while minimising any impact on farm profitability.

“The software prototype is just one example of the enhancement of tools within the programme to help farmers make effective decisions on which mitigation strategy to use based on their cost and what is most suitable for their farm type.”

Over the next 18 months Ballance and other end users like Regional Councils will help test the model to confirm the level of certainty that can be achieved by applying it to particular farm systems and catchments.

Another project within the programme examines what the baseline values of water quality analyses – e.g. nitrogen, phosphorus, sediment (including clarity), and faecal indicator bacteria (E. coli), among others – would be in our rivers and streams with no human activity. Work has shown there are large differences according to geology, climate and hydrology. The difference between current values and the baseline shows the true relative influence of human activity and will help the setting of targets in areas where the stream may be naturally clean or, for instance, turbid.

More importantly, the two projects can combine to show how far losses can be reduced. This should help to bring about a consensus on the level of losses that are acceptable.