Marc Gascoigne: The truth about cow poo and other myths

Most cow No 2s are deposited straight back onto the land, to be broken down by microbes and become part of the top soil.

Most cow No 2s are deposited straight back onto the land, to be broken down by microbes and become part of the top soil.

OPINION: I've quite often read or heard over the last few months that each dairy cow produces the waste of 14 humans, which apparently translates into New Zealand having to deal with the waste of an equivalent population of 90 million people.

Often the implication is that all of this waste is washed straight into our rivers and waterways.

Yeah right.

​What is conveniently left out of this argument put forward by our critics is that the vast majority of cow No 2s are deposited straight back onto the land, to be broken down by microbes and become part of the top soil, boosting fertility and being used to grow more grass to feed cows. What a great system for dealing with waste!

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I don't think you can compare human waste with cow waste either – last time I checked I didn't see our cows chucking out plastic bags, old TVs or disposable nappies, so it's hardly comparing like with like.

Another myth I hear quite often is that modern farming methods are destroying our soils and stripping them of their ...
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Another myth I hear quite often is that modern farming methods are destroying our soils and stripping them of their fertility.

Cow shit today was simply grass yesterday. I've had my fair share of yesterday's grass splattered onto me in the cowshed. But it's all part of the job and you hose it off and get on with it.

Recently I've seen where a lot of cow waste ends up. I've been putting up a new fence on the farm and some of the holes I dug in areas where cows have been crapping the most had top soil for the whole depth of the hole – wonderful dark rich and fertile teeming with big fat earthworms.

Which brings me to another myth I hear quite often – modern farming methods are destroying our soils and stripping them of their fertility. What a load of cobblers.

We've been dairy farming on our farm for 23 years and I would say from personal observation that the exact opposite is true.

The top soil is deeper and healthier and we are growing more grass. The soil tests done each year also show a healthy, well-balanced fertility profile which has meant we haven't had to put any phosphate fertiliser on for the last three years.

In short, our soils are not being destroyed.

Digging post holes not only had me thinking about the increasing depth of our top soils but of the carbon that is being sequestered into them. Often we hear or read about New Zealand's overall carbon emissions being high because of our burping and farting cows, but why is there never a mention of the huge amount of CO2 sucked out of the atmosphere by our ever-growing pastures? Why is that not included in calculating our overall emissions trading cost?

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Yes, some of it will be re-emitted by animals as methane, but at least some will be sequestered into the soil. And at least with farming it is a balanced process, ie carbon in (CO2 absorbed by the grass) and carbon out (methane emitted by the cows), unlike sucking fossil fuels out of the ground after it has been locked there for millions of years and releasing it into the atmosphere.

Recently when I was in Europe I noticed that every time I looked upward I could count at least eight big passenger planes criss-crossing their jet streams. It's hard to fathom that cows are the big problem.

Another myth I have heard and read often lately is that it takes 1000 litres of water to make 1 litre of milk. What a waste of water!

That had me pulling out the calculator to see how wide of the mark that is.

On our farm, we hit our peak milk production in October each year. On a daily basis, we are producing 13,000 litres on average.

So at 1000 to 1, apparently we would need to be using 13 MILLION litres of water every day!

Considering our water storage tank holds 45,000 litres, it's obvious that the 1000 to 1 figure is ridiculously inaccurate.

Actually, we have measured the amount of water used on our farm to comply with our resource consent. The actual figure is 4.1 litres of water per litre of milk. Just a bit of a difference.

I can only assume that the 1000 to 1 figure includes the rain that falls and grows the grass that our cows eat. We get 1100mm of rain on our farm each year, which means that overall we get 2.2 billion litres of water falling from the sky.

That's a lot of water. How is it a waste to use it to produce food?

Marc Gascoigne is a Cambridge dairy farmer and welcomes feedback at marcmaria1@gmail.com

 - Stuff

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