Intensification benefits untrue

20:40, Nov 28 2013

New Zealand needs to stop its rush to intensify agriculture, argues Mike Joy.

More water storage-irrigation schemes are planned for many parts of New Zealand.

On the face of it increased agricultural production sounds like a great idea, bringing a much needed boost for the economy and even some protection from climate change impacts.

But is it really that simple, and who are the winners and losers?

There is incontrovertible and stark evidence that the progression from large scale irrigation to farming intensification (usually dairy conversion) gives rise to increased environmental degradation.

Notwithstanding ratepayer and taxpayer subsidies, the huge capital investment required for irrigation infrastructure necessitates conversion to more intense and inevitably less sustainable forms of farming.


This progression creates gains for a few entrepreneurs, some increase in production, but not necessarily profit, and does not take into account the losses for many.

There are gains for the developers, the suppliers of infrastructure, and capital gains for the existing landowners but the biggest winners by far are the financiers.

More investment for infrastructure and the resulting increased land prices lift farm indebtedness and given that New Zealand farmers are already among the worlds most indebted that is the last thing we need.

The environmental issues arising from irrigation fall into two broad categories; first the local ecological impacts of a dam on the waterway, and second the ensuing impacts arising from the obligatory intensification.

The water used for irrigation eventually ends up laden with nutrients, in either groundwater or back into the river downstream, causing human and ecological health issues.

On top of the freshwater impacts are intensification impacts on the land, with heavy metal (cadmium) contamination of soil from the overuse of fertilisers and soil compaction from high stocking rates.

Of the many ecological effects of the dam one example is the blocking of native fish migration both up and down stream; with two thirds of our native fish listed as threatened we are already among the world's worst. So every dam becomes yet another blow to freshwater biodiversity.

Then there is the lake formed by the dam; it blocks the downstream movement of sediment which builds up behind the dam and scours out the riverbed downstream. This build- up of sediment can make these lakes short-lived, for example the Patea dam built in 1984 had lost half its volume by 2010 through sediment in-filling so in another few decades will be virtually useless.

The lakes provide very poor habitat for most of our native flora and fauna because the unnatural ramping up and down of levels makes the shoreline virtually uninhabitable and prone to erosion. The claims made by irrigation promoters of improvement in habitat quality or water quality downstream are completely baseless.

The effects of irrigation intensification on human health are already becoming obvious in Canterbury. The medical officer of health there called the rising nitrate levels in groundwater a ticking time bomb.. What's more, there are considerable lag times for nitrate build-up in groundwater so we are only just beginning to see the effects of problems we created perhaps 20 to 30 years ago.

To give some economic context to the nitrogen health issue, a high producing Canterbury dairy farm under irrigation leaches 130 kilograms of nitrogen for every hectare, every year.

Just one kg of nitrogen will pollute just over 88 cubic metres of water from pure to the level where it is undrinkable. A typical irrigated farm of 400 hectares will thus pollute 4.6 million cubic meters of water every year. To remove that leached nitrate to make it drinkable again will cost somewhere between 50 cents and $1 per cubic metre. So for that polluted water from a single large farm to be made safe for human consumption would cost at least $2 million, many times more than the profit on the farm to pollute it.

Federated Farmers has been strident in claiming the advantages of water storage to mitigate climate change impacts. But this argument is only credible if the water is actually reserved solely for a drought, the reality is that, as described above, a dam just drives more intensification so that when the drought inevitably comes even more animals and farms are at risk.

In the end, the vast majority of New Zealanders are worse off, losing the very values that once made this country unique - clean safe water to drink and swim in and clean safe food. The big question then becomes; is irrigation and farming intensification better for the country? The environmental record says a clear no; the economic question has never been answered because there has never been an honest evaluation of the real costs.

Yet another problem is that intensification means more reliance on external, unsustainable inputs like fertiliser from the Middle East and palm kernel from Asia.

We are running up a huge economic and environmental debt for dubious worth of supplying the world with the lowest value milk products.

Ultimately, large scale irrigation and agricultural intensification is a social justice issue. Cultural, aesthetic and ecological wealth is being usurped by a small sector of society at the cost to all New Zealanders.

We can easily lead the world in producing sustainable safe clean food. We must change and make that the norm and stop this race to the bottom.

Mike Joy is a senior lecturer in environmental science/ecology at Massey University.

The Dominion Post