Sustainable farm systems needed

Will we accept firm water quality limits in our agriculture, Dugald MacTavish asks.

Farmers say water quality limits could threaten farm viability. Photo ODT files.
Farmers say water quality limits could threaten farm viability. Photo ODT files.
Our New Zealand farmers have been enormously resourceful and highly successful at evolving the clever and productive farming systems that form a cornerstone of our economy.

This has not been without its costs, however, and state-of-the-environment reporting has cast a harsh spotlight on its effects on our waterways; most notably in sub-catchments with intensive dairying.

A Niwa study of about 300 lowland waterways in New Zealand showed that 96% in pastoral catchments, and 100% in urban catchments, failed the pathogen standard for contact recreation.

More than 80% of the sites in pasture catchments exceeded guideline levels for phosphorous and nitrogen. More than 60% of our native freshwater fish are now listed as threatened with extinction.

In response to this, the National Policy on Freshwater Management requires all regional councils to set firm limits on the take and discharge of contaminants to stem deterioration of water quality in our rivers.

Otago Regional Council commissioners hearing submissions on the ORC's recent proposal to set water quality limits for discharge to land and water have faced an avalanche of farmers and their experts arguing these represent a genuine threat to farm viability.

Similarly, farming interests in the Manawatu are appealing the Environment Court's decision in favour of a plan to set water quality limits to improve the Manawatu River.

In response, the Government has shown the old attitude that environmental consideration is OK just so long as it doesn't get in the way of the economy, is still alive and well.

Commenting after the Environment Court decision, Primary Industries Minister David Carter indicated it would be unacceptable for regional councils to set nutrient load limits that constrained farm profitability, and that the RMA might need review to ensure more thorough economic-impact assessment of such proposals.

Yet other evidence at that same hearing cited specific examples of farmers' successfully reducing their nutrient footprint by a third or more with relatively straightforward management changes, sometimes even improving profitability.

So is it wise simply to legislate farming around this one in the same way we have for greenhouse-gas emissions?

In 2009, a group of international scientists identified nine "planetary boundaries" or biophysical thresholds beyond which the cumulative impact on the planet exceeds its carrying capacity and becomes unsustainable. These included global freshwater use, the phosphorus cycle flow and the nitrogen cycle flow.

They concluded the last two have already exceeded safe boundaries, reactive nitrogen hugely, and that nitrogen flow into the earth system must be reduced by 75% at a global level.

Even with best practice, containing nitrogen leaching under intensive outdoor farming is very difficult, and in combination with phosphorus is the primary cause of eutrophication and algal growth and, in some cases, toxicity in our freshwater systems.

Together, they may also cause similar undesired non-linear change in terrestrial and marine systems, indirectly aggravating climate change.

The same scientists found a risk of global phosphorus scarcity in coming decades. So more efficient use and retention of phosphorus within agricultural ecosystems would reduce both pollution and farm vulnerability to shortage.

It is clear that in New Zealand we have reached a land-use crunch point.

Best science is telling us that, for the safety of our local and global environments (and, indeed, for the integrity of our pure marketing brand), we need to operate our land use and other systems within ecosystem limits.

Adhering to those limits will inevitably have economic implications for some businesses and communities.

But if compliance is not possible, wouldn't that indicate the high nutrient and water (not to mention high energy, emissions, capital and often debt-laden) industrialised farm model in which the Government holds such hope has proven a potential liability in an increasingly resource-constrained world?

I'm sure all water users would feel better knowing they were returning free, publicly owned water fit for others to enjoy.

So while there may be some pain, surely the sooner we accept critical limits, the sooner we can again start to develop world-leading but more sustainable and robust farming systems. Indeed, if the planetary implications of failing to do so are real, do we have any choice?

 - Dugald MacTavish is a water resources consultant based at Moeraki.