Recently the New Zealand Herald published an article by Malcolm Lumsden that subjectively compares pollution by people with dairy cows.

The original article can be found at:

Here I provide a rebuttal to his alternative facts:

Whilst his claim that over the women in question’s lifetime that she will produce the same amount of pee and poo as one cow is probably correct, he does not make a fair comparison; when one cow dies there is another taking its place – over the women’s life time there will be 11 cows worth of poo and pee not one (assuming a one-one comparison).

He claims that the Waikato River is the “fourth cleanest in world.” Can he please provide evidence for this? I am unaware of a study that compares the water quality of all rivers in the world and it’s unclear by what parameters he is making his judgement. In terms of nitrates, dissolved oxygen fluctuation, sediment and MCI (measure of aquatic bug health), there are numerous rivers throughout New Zealand that exceed the Waikato River in water quality.

He’s right that Daisy the cow will spread her poos and pees on the land where it gets filtered. However, the amount of filtering that happens is small. Cow pee has a higher concentration than human pee and gets dumped on a very small patch of land. The grass and soil microbes can only assimilate a small portion of it; the rest travels through the soil into our waterways where it fuels algae growth. As for most towns in NZ, the wastewater treatment process is a lot more involved than simply removing the solids and pipe discharges are being replaced rapidly with land based discharges. By way of example, the nutrient loads in rivers in the Manawatū confirm the correlations with land use and reveal that the majority of nutrients in lowland rivers come from diffuse sources rather than point sources (out of pipe).  The Manawatū River at the gorge carries 2280 tonnes of nitrogen, of which only 1.2 per cent (29 tonnes) is from point sources, and 54 tonnes of phosphorus, of which 13 per cent (7 tonnes) is from point source origin; the rest is from diffuse sources, which is almost completely from agriculture (Ballantine & Davies-Colley, 2009; Roygard, Mcarthur & Clarke, 2012).

I concur that urban stormwater has many nasties in it. A move towards biodegradable chemicals and using wetlands to filter stormwater runoff is needed. However, stormwater runoff has far less impact on the biological communities in rivers than nitrogen and phosphorus (key components of fertilizer).

He claims that science says we need twice as much land for organic farming. That simply isn’t true, trials comparing conventional versus organic farming at Massey University have shown that both forms of farming can produce similar outputs – except one does not rely on fertilizer and has higher value. Moreover, if we want to feed the world then dairy farming is an extremely inefficient way of doing so. Plant based milks use a small fraction of the land, with far less inputs and outputs than dairying, and do not rely on fossil fuel fertilizers and palm kernel from the deforested Orangutan dwelling rainforests of Indonesia.

He may view the likes of Dr Mike Joy as an extremist; he’s welcome to call him what he likes but Mike uses peer-reviewed science to back his claims. If Malcolm wishes to seriously contend Mike’s arguments then he should also use scientific evidence to back up his claims. The only way we will move forward with this contentious issue is if we get our heads out of the sand, hands out of our own back pockets, put our prejudices aside, and take an objective, evidence-based approach. It is concerning that decision makers, such as Brett Hudson MP and Louise Upston MP, effectively endorse the subjective, misinformation presented in this article on their Facebook profiles – it reeks of Trump-like support for “alternative facts.”

It is not true that we all want “meat, milk, and other animal products removed from our diets.” What we want is for humans to consume a diet that fits within Earth’s capacity to produce. There is no doubt that large reductions of dairy and beef will be needed. I’m not saying we all need to become vegan, but we do need to conduct serious analysis into what a healthy and sustainable diet looks like and make the tough decisions to get there.

Malcolm had a grizzle about the potential Waikato plan change which he claims “will dictate land use, stock numbers, fertiliser use, what type of crops may be grown and where, plus much more.” Firstly, the plan is only in submission phase. Secondly, the public of New Zealand are heavily subsidising the costs of dairy farming by allowing environmental and social degradation to occur free of charge. We don’t charge them for their water use; we don’t charge them for the sediment they are sending into our rivers; and we don’t charge them for killing our fish and rendering waterways unswimmable. Why should we give one industry a free ride, actually a heavily subsidised ride, when others, including other farming industries, are expected to survive without such subsidy? Thirdly, well-functioning economics relies on both parties in a transaction to have the ability to assess a transaction and say no if they wish. When was the last time anyone heard a fish or tree or bug agree to a transaction or say no? Ecological communities are reliant on mutualism for long term survival. Our one-way, take from the environment, deal is not mutualistic and is a risky business. The least a farmer, actually all humans really, can do is strive to live with as little environmental externality as possible.

To finish off, we can all point the finger as much as we like, but as long as we continue to buy products that have high environmental impacts then we are essentially supporting their continued production. We are all responsible for the mess we are in and we should all make the effort to read evidence-based evaluations of products and vote more wisely with our wallets.

Adam Canning

Ballantine, D., and R. J. Davies-Colley. 2009. Water Quality State and Trends in the Horizons Region NIWA, Hamilton.

Roygard, J., K. Mcarthur, and M. Clarke. 2012. Environment Court Expert statement technical evidence – Oneplan appeal. Horizons Regional Council.

6 thoughts on “A reply to: “Malcolm Lumsden: Who is the greater polluter, cows or people?”

  1. I live on the Waikato at Ngaruawahia and I can tell you that your summary of the situation, hits the mark. The situation further down river, gets worse as you make your way to Port Waikato. Either side of the river is flanked by dairy farms and the associated effluent.
    Being raised in Canterbury in the South Island for the first 20 years of my life, our family had the pleasure of regularly going to the Selwyn River at Chamberlains Ford. In the 1970’s, the water was so pristine, you could drink it while swimming in it. The same applied to the other meandering rivers in Canterbury such as the Rakaia, Ashley and Waimakariri…etc.
    Today, the change for the worst, is in stark contrast. Where once, the Canterbury rivers were bordered by pasture and sheep farms; today, dairy has pre-eminence over other forms of farming. I was shocked to find that No Swimming signs (because of algal bloom) were posted as far up the Selwyn as Glentunnel; which is getting pretty close to the rivers head waters at the foot hills on the way to the Alps.
    It seems as a laymans point of view, that the water draw-off from the rivers for irrigation is so excessive, that the concentrated effluent from dairy farms is displacing what would have been the normal water flow. This would account for the increased algal bloom due to increased nitrogen run-off.
    I don’t want to sound like a politician, but it’s time for NZ to take a step back and review the situation. This is serious. If there is a lack of political will or accountability to change the situation; then the combined forces of ordinary people, the scientific community, environmentalists and organic farmers; have to join together to force the issue. Cheers.

    Liked by 1 person

    1. Hi Justin,

      Thank you for sharing and I agree! When I lived nearby Selwyn River several years ago and I could easily cross the river in my socks without getting my feet wet.

      Your observation is exactly right! The more water abstracted, the more irrigation, which means more fertilizer, greater nitrate leaching, and the water the filters back through to the river is highly concentrated in nitrate. The higher the concentration of nutrients, the more algae that grows. Also, when more water is removed from a river the less tumbling of cobbles occurring, which prevents the scouring of algae so allows it to build up. High algae with low water is a recipe for hypoxic conditions to occur and deprive aquatic life of oxygen.

      Indeed! Unless we act now, it will only be harder, if not impossible to restore our ecosystems – we can’t bring species back from extinction.

      Again, thanks for your contribution!



  2. It is not only Nitrogen compounds that exit the cow in its urine. There is also oestrogens, specifically 17Beta oestradiol, 17alpha oestradiol, oestriol and oestrone. These get into waterways and can affect the gender ratio of fish, turning juvenile male fish into females. This is not great for fish reproduction, too many females and not enough males. I have measured oestrogen at ten sites in rural drains and streams in Mid Canterbury and the oestrogens are there. Furthermore I had the results checked by a lab that specialises in steroid hormones using a different detection method and they confirmed that the oestrogens were in the samples that I supplied.
    There is some work that suggests that environmental oestrogens may have also an effect in humans e.g. breast cancers and low sperm counts in males.

    Kim Baronian


    1. Thanks for that Kim!

      Hormones getting into waterways is not something that is often raised but is potentially very significant. Has that work been published at all? I’d love to have a read.

      I’d be interested to see if the hormone concentrations are at levels high enough to affect fish and if that, in turn, leads to differences in the overall fish community.



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