Reconsidering the solutions to farm pollution
Just because nitrogen is leaching into waterways from farms doesn’t necessarily mean that individual farmers are to blame, a river health expert says.
Director of the Griffith University’s Australian Rivers Institute, Stuart Bunn, said many places in New Zealand and Australia with river health issues were dealing with the fallout from colonial-era decisions.
‘‘When you look at rural places, they’re dealing with legacy issues, things they inherited from generations ago,’’ Bunn said.
‘‘You can’t just say, ‘You’re responsible, you’re on that farm, that’s where the nitrogen is coming from’. [The farmer] didn’t necessarily cause that.’’
Bunn, who was visiting Nelson’s Cawthron Institute this week, said the indiscriminate clearing of land by European settlers, often starting from the rivers, which were used for transport, laid the groundwork for many of the problems that farmers, foresters and rivers were dealing with today.
However, Victoria University freshwater ecologist Mike Joy said much of New Zealand’s poor river health was due to more recent dairy intensification.
‘‘Coming from Australia, and certainly from northern Australia, the changes that happened there weren’t anywhere near as sudden and recent and intense [as in New Zealand]. We had this really, really recent intensification, and a massive increase in irrigation to allow that intensification,’’ he said.
‘‘Stocking rates have gone up drastically in the last 20 to 30 years . . . so you have to add lots of nitrogen fertiliser, which is made out of fossil fuel. And a little bit of the nitrogen fertiliser goes into the milk, but most of it, 75 per cent or more, goes out of the cow through urine.
‘‘That is kind of nitrate fertiliser in that urine at an intensity that the grass can’t use, because it’s just too much of it in a small area. So it goes past the roots of the grass and into the groundwater or into the gravel, which makes its way into aquifers and rivers.’’
Joy said that while riparian planting helped to reduce sediment runoff and over-land contaminants like E.coli getting into rivers, it wasn’t enough to reduce the underground leaching of nitrogen-based fertilisers into waterways.
He said the current intensity of dairying was the issue, and at that level, any mitigation other than reducing intensification would have a minimal impact.
Bunn said that whether the mitigation was done by reducing stocking rates or by fencing and planting around waterways, there was a need for ‘‘much more clever ways to incentivise that action’’.
He said there was a mix of foresters and farmers who were taking steps to mitigate their impact on rivers, but ‘‘if you’re relying on individual land owners to do a public service by protecting their patch, we’ve got to do more than that’’.
He said one way was to create a market for environmental action, something that was not necessarily as difficult as people might think.
‘‘You can pay a farmer to plant more trees . . . we need to think beyond that: what about nitrogen? What about sediment? Could we monetise them? We know exactly what the cost of water treatment is with and without good water quality.’’
Bunn said people or organisations downstream from polluters were usually left addressing the symptoms of upstream problems, but those methods were potentially more expensive than an environmentally-focused preventive measure at the source.
‘‘You might spend $1 billion building a water treatment plant. Or what if you spend $500,000 rebuilding a wetland and getting the same reduction? What if you could achieve that by working upstream?’’
He said activities like wetlands restoration and riparian planting were natural and sometimes less expensive ways of either preventing or removing nitrogen and sediment buildup in freshwater.
‘‘If you asked people how much they value the rivers and seas around here, they would rank it really highly . . . but when it comes to ‘How much would you spend on it?’, people value it but don’t want to pay. Increasingly, we’re . . . looking to better explain to people why it’s valuable.
‘‘Freshwater systems, their biodiversity is declining at twice the rate of biodiversity on land or in the sea. Since 1970, we’ve lost 80 per cent of our freshwater populations.’’
He said many people thought of efforts to protect the environment as expensive and difficult, but it was possible for environmental protection to be economically efficient and even profitable, with the right research to back it up.