INTERVIEW: The slimy solution to a serious issue - Marie Potthoff on algae pools

“Dairy farming has reached its economic, social and environmental limits.”

So says Marie Potthoff in the opening moments of her presentation “Dirty Dairy and the Slimy Solution” - delivered at this year’s Sir Paul Callaghan Eureka! Awards.

It’s hardly an unpopular opinion.

Steve Carden, chief executive of Pamu (formerly Landcorp), made the same claim earlier this year, saying New Zealand had “reached the economic, social, and environmental limits of how [it] currently farm[s]”.

Greenpeace's agricultural campaigner Genevieve Toop has, for a time now, been saying our waterways “can’t cope” with the number of dairy cows currently in the country, a notion underlined by Agriculture minister Damian O’Connor when he warned we “may be reaching peak cow numbers” in November last year.

So, why is that an issue?

Well, as Potthoff says, cows equal effluent, and effluent equals nitrogen.

Pastoral soils have a threshold when it comes to nitrogen absorption. When they are pushed beyond that threshold by excess fertilizer and livestock waste, a portion of that nitrogen will drain (or leach) as nitrate into the groundwater, eventually ending up in streams, lakes and rivers which resultantly become polluted by toxic algae.

Between 1990 and 2012, the quantity of nitrogen leached from agriculture annually increased by an estimated 28.6 percent (30.4 million kilograms), reaching around 137 million kilograms for the year 2012. Of that number, only 19 percent was attributed to fertiliser - the rest, livestock waste. (Stats NZ)

Now, whilst the sheep and beef cattle industries contributed substantially to this 2012 figure, dairy trumped them both, with an estimated 49.84 million kilograms of total nitrogen leached, followed by sheep at 36.31 million, a dramatic change from 1990, when the dairy contribution was nearly identical to that of beef and substantially lower than that of sheep.

This can be attributed to a rise in dairy cow numbers by 70 per cent in the past 20 years, seeing them reach a current total population of over 6 million.

The result for our national water bodies hasn’t been pretty. Though farmers, district councils and environmental groups have made substantial efforts to restore the poor health of New Zealand’s lakes and rivers in the past several years, a lot more work needs to be done, and done quickly, should we meet the government’s target of having ‘90% swimmable rivers by 2040’.

Adding conservation efforts to their already strenuous workload has meant tough times for dairy farmers in recent years, and times are only getting tougher as they face increasing pressure over another aspect of their operations: feed.

For those unaware, palm kernel extract (PKE) is (and has been since 2015) the most common feed supplement for dairy cows in New Zealand.

The problem with this, as Potthoff explains, is that PKE is high in unhealthy saturated fats - which means our dairy cows are producing milk high in unhealthy saturated fats. Additionally, PKE makes the milk more difficult to process into certain products, and, our increased reliance on its importation (2.2 million tonnes last year) has made us increasingly vulnerable to biosecurity hazards.

In response, Fonterra has begun to regulate PKE use, introducing a fat evaluation index (FEI) which grades farmers on an A-B-C-D scale in relation to the fat content of their milk. Starting next month, dairy farmers will be penalised by as much as 4 demerit points and 20% of profit per collection per day should they fall into the C or D categories, meaning if they want to maintain profits, they will need to begin drastically reducing their use of PKE and find suitable alternatives.

What might those be?

Well, fourth year veterinary science student Marie Potthoff may just have the answer, an answer that could solve, not only the feed issue, but the nitrogen problem as well: algal growth pools.

This week I talked to U.S-born Marie about her ‘slimy solution’ to the multiple problems facing kiwi dairy farmers to find out where the idea came from, how it developed, and where it might lead her in the future:

So when did you come to New Zealand?

When I was 16.

Was agriculture a topic of interest for you in the states?

No, it wasn’t really. A big part of my degree is learning about agriculture, farm dynamics, etc., and I had zero knowledge about that stuff before starting the course.  

This algae pool idea, where did it come from, when did you come across it/come up with it?

Well I originally had a different idea for the Eureka project, but after a bit of research realised it wasn’t a very good one.

So, I was casting around for something else to do the project on, having already invested quite a lot of time and effort in this, and I ended up looking at the ongoing feed shortage issue in the dairy industry and how that could be addressed. I started looking at alternative feed sources and came across this idea of using by-products from algal biofuel creation which really caught my attention. I began researching that and thinking about how it could be applied in New Zealand and figured out that it could be used as an effluent treatment regime as well.

So really, I came from the perspective of addressing the feed concerns, and then figured out from there how algae could not only provide a solution to that but also be a remedy to the effluent issue.

This concept is being researched in Australia, correct? When did that start?

Yes, at the University of Queensland. Their research began quite recently, I believe the study was launched this year.

Was that study a key point of research for you?

Well that’s where I got the food side of the information from.

A lot of information went into the presentation though, stuff relating to algal growth, effluent growth, algal biodiesel production and so on, all which came from elsewhere. The Australian study was just focussed on the food side of things.

Outside of Australia, is the concept in implementation anywhere else yet?

Yes, it’s being used in North America quite a lot. Australia is implementing it purely as a way of growing food, whereas in North America they’re looking at what they can use the by-products of the algae growing process for -  fuel, for example.

How much research went into the presentation? Did you enjoy the overall experience with Eureka?

I did all the research in about two weeks - about 80 hours all up, it was a bit stressful, but I really enjoyed it. I felt like I learned a lot from the experience, just getting to meet all the people involved was great, the other participants were such an interesting group of people so meeting and talking with them was probably the best part.

At the end of your presentation, you were asked about the down sides to this concept. It does seem almost a little too perfect, with all these benefits and seemingly little in the way of drawbacks. Are there any negative effects of the system that, perhaps, you left out of the final presentation?

Well I did bring up the major drawback in the presentation (though I think I downplayed it a bit, so nobody realised it was a drawback) and that’s controlling which species to grow. In a New Zealand environment, it would have to be an outside, pond system, and it would be difficult to control environmental contamination. I think that would be the major downside. It can be controlled to some degree using turbines, but to what degree exactly is hard to say. To some degree you can control the PH of the water and the CO2 of the water, but there isn’t much research as to how closely you can control it, certainly not in a New Zealand environment. So that’s something that would have to be looked into.

The other thing that might be a weakness is that there’s a huge range of values for how much yield can actually be produced. I picked numbers for the presentation that were sort of in the middle of that range, but again, with the research not having been done in New Zealand yet it’s hard to say how much would actually be produced in practise in New Zealand.

 Have you talked to many dairy farmers about this, what sort of reactions have you gotten from them?

Yea I have, there’s always some market research involved in working out the feasibility of an idea like this and getting a feel for how it would be received.

The attitude I got from farmers was: “if it’s going to solve a problem then it’s something worth looking into”. I just made sure to be clear about what problem it’s solving, and a big focus during my research was making sure the practise isn’t going to do more harm than good.

You use the term “dirty dairy” in your presentation (in fact it’s in the title), did farmers have a problem with you using that phrasing?

Well I avoided using the term around them, for sure.

I approached it from a more positive perspective when I talked to farmers. For example, I asked them about the embargoes being pushed on palm kernel extract and what they were planning on feeding their cows, and, if an algal alternative existed, how they would feel about that. And I asked them about their effluent systems and whether they would consider switching to something like this, you know, things like that.  

It was about seeing how receptive they were to the idea and finding out what their plans were for dealing with the immediate issues facing the industry and whether this system appealed to them.

And on the whole, they were pretty open to the idea?

Yea, in general. Obviously, there’s still a lot of research to be done, but the idea seemed to interest most of them.

Would you say raising awareness is key with something like this? Is that one of the biggest issues the idea faces?

Yes, certainly. I think everyone is very aware of the problems facing agriculture and the environment now, so being able to say, “hey, this is a solution and it’s viable” is important, because people are looking for solutions at the moment.

What are your future plans for this project? How do you see it going forward?

I’m kind of looking into it now with some people at Massey. There’s a technical development company that is exactly for innovations like this which I’m having conversations with. It looks like it’ll be a slow process though.

It may just develop into a very time-consuming hobby rather than something career-driven, but there’s definitely potential there for more work.