Holy Cow! Too many cows in New Zealand


We eat their meat. We drink their milk and make cheese, butter and cream products. We use them to introduce children to agriculture. Its beef is one of our favourite meats at the supermarket. But holy cow, New Zealand has a problem with their environmental footprint.

In Canterbury alone it is estimated that there are about 1.3 million cows, or about 2.1 for every single person living in the province. Each cow will produce the effluent equivalent of about 11 people going to the toilet, or between 14-15 million people in Canterbury. And Canterbury is paying a steep environmental price for it. In 2007, prior to the National Government of Prime Minister John Key taking office, the number of dairy cattle in Canterbury was 754,000. By 2016 that number had risen to 1.27 million.

The province, which is noted for its superb thousands year old ground water in deep aquifers under the Canterbury plains is in danger of having its drinking water supply wrecked by the spread of nitrates. Dr Alistair Humphries believes that in 100 years, it will not be possible to drink the tap water in Canterbury.

Each cow needs many litres of water to ensure it can drink, to ensure that the grass it will eat is adequate. A litre of milk will take about 1,000 litres of water or 1m³ to manufacture. In other words the 2 litre bottle of milk in your fridge takes about 2,000 litres (2m³) of water. In order for a 500 cattle farm to produce the roughly 2 kilogrammes of milk solids that each healthy cow will put out at their peak per day, roughly 1,000,000 litres of water or 1,000m³ will be needed. That has to come from a ground water source or be diverted from a river. As one can imagine in a country where dairy farming contributed $14.4 billion to the New Zealand economy in 2016, the pressures on our freshwater resources both at the surface and in the ground are considerable.

Many farmers are making an honest effort to reduce the impact of their herds on the natural waterways of New Zealand. Measures include fencing off streams so that easily erodible dirt banks are not crumbled, and to stop them defecating and urinating in the water. Some are replanting shelter belts that were torn down when the farm was converted to dairying so that irrigators could move through. Replanting damaged river banks with low level plants that help to anchor the bank is another measure.

However there is a problem. Cows also make a substantial contribution to New Zealand’s greenhouse gas emissions. The estimated contribution of the dairy sector to New Zealand’s overall climate emissions are about 43% caused by carbon dioxide and about 11% caused by nitrous oxide. The gases mainly come from biological processes – livestock burping in the case of the carbon dioxide and cows urinating in the case of the nitrous oxide.

It has been acknowledged with some resistance on both sides of House of Representatives. Initiatives have been tried such as developing grass that does not induce so much burping, alternative forms of fertilizer to reduce the amount of nitrates going into streams and medical research to see if the nitrous oxide discharge can be reduced.

But for all the good work these farmers are doing, it does not address the core problem with the 10 million cattle in New Zealand – there is simply too many, and the total defecation and urine output from them all would be roughly equivalent to about 140 million people or about 85% of the population of Bangladesh. Large scale depopulation of herds is not something a dairy farmer will want to do and it will be a vote killer for a lot of politicians if they are brave enough to try. Unfortunately the cold nitrate loaded fact of the matter is if New Zealand wants its clean green reputation back, several million cattle are simply going to have to go.