Drs. Wafa Malik and Patrick Durand discuss their research modeling Nitrogen pollution mitigation strategies.
Eutrophication is a state of overgrowth of aquatic plants, such as algae and seaweeds, in water bodies due to the excessive pouring of nutrients from different sources like agriculture, industry, and human settlements, causing disturbances to the ecosystems. Coastal eutrophication is a major issue worldwide due to the increasing discharge of nutrient emissions from agricultural activities into coastal ecosystems. Several efforts have been made to reduce eutrophication, achieving up to 35–40% reduction, but these measures are not sufficient to eliminate the problem. For more sustainable and effective solutions, the root causes of the nutrient emissions, especially nitrogen, need to be addressed in current agricultural practices. In this episode of the Field, Lab, Earth podcast, Drs. Wafa Malik and Patrick Durand share their research on the reduction of coastal eutrophication in Brittany, France, focusing on changing cropping systems and reducing the sources through modeling the effectiveness of different approaches and taking into consideration the interests of farmers and the local community. If you want more content like this don’t forget to subscribe to us here on this channel or anywhere podcasts are found.
Featured Article, Full Episode Show Notes, and Transcripts
“Nitrogen mitigation scenarios to reduce coastal eutrophication” published in Agrosystems, Geosciences & Environment: https://doi.org/10.1002/agg2.20319
Show notes: https://fieldlabearth.libsyn.com/mitigating-coastal-eutrophication-with-drs-wafa-malik-and-patrick-durand
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Abby Morrison: Hello and welcome to Field Lab Earth, the podcast that’s all about past and present advances in the fields of agronomic, crop, soil, and environmental sciences. Today we’ll be talking to doctors, Wafa Malik and Patrick Duran about reducing nitrogen pollution into coastal waters. Coastal water pollution from agricultural
Sources is a major issue worldwide, leading to algae blooms, dead zones and more. Several efforts have been made to reduce this problem, but for more sustainable and effective solutions, the root causes of these nutrient emissions need to be addressed. This episode, Wafa and Patrick
Share their research on the systems they’re using to model potential solutions and just how effective these solutions may be. I’m your host, Abby Morrison. Let’s talk about science. Hi everyone. Welcome to the show. Today we have Wafa Malik and Patrick Duran with us
Wafa Malik is a postdoctoral researcher at the National Research Institute for Agriculture, Food and the Environment, or INRAE, in Rennes France. She holds an engineering degree in Natural Resources Management from the High School of Agriculture in Moghrane Tunisia and earned her master’s degree in Integrated Planning for Rural Development and Environmental Management
From the Mediterranean Agronomic Institute of Zaragoza Spain, she was awarded a doctorate in Agricultural and Environmental Sciences by the University of Zaragoza Spain. She subsequently held a postdoctoral position at the University of Kentucky in Kentucky USA. Her current research interests focus on how to change agricultural activities and land use management to enhance
Environmental sustainability and agricultural productivity using agrohydrological methods. Patrick Durand is a senior scientist trained in agronomy soil science and hydrology. His early works were on mountain catchment acidification and hydrology in the University Orleans, France, and in the Institute of Hydrology of Wallingford UK with Dr. Colin Neal. He got a permanent
Research position in INRAE, Rennes France in 1992 where he began to work on agriculture, diffused pollution and nitrogen cycling in rural areas. He contributed to the development of several catchment models such as Inca and TNT2, both for research purposes and for policy support. Hello,
Patrick and Wafa. So good to have you on the show. Thank you for your time today. How are you doing? Patrick Durand: Quite well. Hello everybody. Thank you for having us today. Wafa Malik: Hi Abby. Hi everybody. I’m doing well,
Thank you. Thank you for having us on the show. Abby Morrison: Good. Yay. Yeah, so happy to have you. So today, if people weren’t able to guess some of this from your lovely bios, we are talking about eutrophication, the nitrogen pollution that occurs
In different regions, specifically in Brittany France. So if you could start us off by telling us just a little bit more about Eutrophication, how you would define that term, and also how that comes into play specifically in Brittany. Patrick Durand:
Okay. As you may know, eutrophication is, it means an excessive load of nutrients coming into an ecosystem and causing severe disturbance to these ecosystems. So it has different forms, different symptoms. It can be harmful microalgae blooms, it can be dead zones due to lack of oxygen
In the water, fish scales, red waters, et cetera. In Brittany, it’s particularly the problem of green tides that is acute. The green tides, it’s the tremendous development of a sort of seaweed microalgae, a green seaweed, which is not toxic at all, but it tends to accumulate in large
Proportions and making heaps on the beaches, which cause a lot of nuisance and even problems for the health because when these heaps are rotting it emitted different sort of gases and especially hydrogen sulfide, which is a very poisonous gas. So this is quite a very problematic issue in
Brittany and previous studies have shown that the main cause of this phenomenon is the excessive load of nitrogen coming from the streams that feed the coastal areas. And these nitrogens come from, mainly from agriculture. And indeed Brittany is one of the major regions for agricultural
Production in Europe producing mainly animal products, dairy, cattle and meat cattle, pigs, poultry, et cetera. So in the past of course there has been many mitigation policies that have been implemented and indeed we have managed to reduce the nitrogen loads by about 30, 40% in
Most of the areas. So this is going better, but it’s not enough to get completely rid of a problem and especially when the weather is particularly favorable to the development of this seaweed, we may have a very large green tides until now. Abby Morrison:
I just didn’t realize that weather could have such an impact on that phenomenon. So that’s news to me. Patrick Durand: Yes, and Brittany is not the only region that is affected by this phenomenon and the most famous
Impacted region is in China where some beaches in the south of China are completely full of tons and tons of weeds. It’s really quite impressive to see and it is widespread in every places where you have a mixture of diffused pollution coming to the sea and quite calm waters, it can happen.
Abby Morrison: Sure, sure. So your research then was specifically studying some different mitigation strategies that you can use to advance further the mitigation that you have already done in that region. So I know you wanted to speak specifically to the description of this coastal region and its kind of geographical context that
Might set this region apart from other regions that deal with this issue. So I wanted to give you an opportunity to do that before we hop into what you tried. So if you could go there. Wafa Malik: Yeah. So specifically in our study we chose
To focus on the striking case of the Sandbrook Bay. It is located in northwest of France, which is one of the most heavily impacted bay by large algae blooms in Brittany accounting for over 70%
Of the total algae standing area in all Brittany. So in fact, this bay is fed by three main coastal stream that collectively drain an expansive watershed covering 800 square kilometers. So it is a rural area that it’s characterized by gentle slopes and mild oceanic climate. I mean
That with annual rainfall more than 700 millimeter and annual temperature around 11. And basically the landscape of this region is dominated by intensive agriculture livestock, which including indoor pig breeding, diary culture and poultry. And the land use consists approximately
One third dedicated to grassland, and one third winter cereals, and one third to silage maize. Abby Morrison: Okay. And so then you were trying to find mitigation strategies that would work specifically in this region, but hopefully
Also have use elsewhere. So what were the methods or strategies that you were looking at with this and how did you test to see if they would work? Wafa Malik: Yeah, great questions. So in our study we aim to assess efficiency of different nitrogen mitigation
Strategies to reduce nitrogen emission to coastal water in this bay. And as Patrick mentioned before that there is the previous mitigation plans have focused mainly on implementing practices that align with European Union regulations. So for example, these practices include adjusting
Fertilization rates to match crop requirements and reducing the excess of nitrogen from livestock and introducing catch crop after a summer harvest. But this for achieving further reductions in nitrogen losses require more drastic change. So we evaluated two potential strategies. The first
One was to extensify a limited part of the area principally in the valley bottom. And I mean this approach aimed to reduce the overall nitrogen pressure and intercept nitrogen losses from up slopes field whose management remain unchanged. So in practice, I mean this means to increase the
Percentage of agriculture land conversion into a managed grassland from a downhill to uphill. And the second scenarios consists on changes in crop systems across the entire area aiming at limiting nitrogen input and maximizing efficient soil coverage by nitrogen catching vegetation
Throughout all seasons. Because in Brittany it’s known for its humid and mild autumn and winter conditions and with soil exhibiting high mineralization potential. So it is crucial to establish actively growing vegetation cover during these seasons. So which is in contrast
To conventional rotation based on silage or grain maize and winter cereal in this region. So in practice these scenarios involves decreasing spring crops which cannot be flowed by catch crop, replacing winter cereals by catch crop and spring cereals and replacing all
Mineral nitrogen with the livestock influence and avoiding potential over fertilization. So these two scenarios then were combined and we compared these scenarios to the reference scenarios that correspond to the combination of current land use and agriculture practices. And this lead us to our
Research questions which are what’s the efficiency of each scenarios and what’s the response time of the system of the two options? I mean, what’s the time delay between the implementation of nitrogen mitigation measures and the full time effect on water quality and what reduction could be resolved
From the combination of the two options? Abby Morrison: Hi everyone, I hope you’re enjoying the show. Interested in learning more? Wafa and Patrick’s paper, nitrogen mitigation scenarios to reduce coastal eutrophication published in Agrosystems Geosciences and Environment is always freely available if you are a certified crop advisor
Or certified professional soil scientist. You can take a quiz for continuing education units for this episode, which can be found in our show notes or in certifiedcropadvisor.org. Let’s get back to the show. Sure. So modeling is always just a
Hard topic for me because it’s very complicated and I always kind of struggle, but I’m going to make an attempt to ask some clarifying questions and please just correct me if my questions are the wrong type of question to ask about a model. So what are some of the variables that you are
Testing in these? Is it the percentage of area that you’re converting? Is it where along that slope you’re converting different ratios of different cover crops or which catch crops you’re using? What are the factors that you are toying with in this model to tweak your design?
Wafa Malik: So good question. So for example, for the first scenarios that I described about the conversion agricultural land use to and managed it and grassland, we used. The conversion began from the wettest part of the landscape, which were determined using autographic index. And this conversion process ranged from zero to 100%
Of the total area. So we began the index, we began from the down slope and we progressively go to the uphill and we tested the several percentage, like for example, zero or 3%, 10%, 20% until 100%. And
For the second one, which is that consists of the changes of all the area, the production system of all the areas. So with the script we can detect with the agriculture practices that we have to change and also the land use that goes the most nitrogen losses to convert it to, for example,
Spring cereal or catch crop and spring cereals. Abby Morrison: Okay. I have additional questions about the models. So I know you had mentioned using livestock effluent. Does your model care what kind of animal that you’re using? I know you mentioned
That there’s cattle and pigs and poultry. Is that something that’s a factor or is there just this is the affluent number or series of numbers that we’re plugging into the equation? How does that interface with this? Wafa Malik: The model that we use, absolutely it can differ. We defer the different effluent
And we manage the different effluent with the different agriculture area for the crops. So the model differentiates between the different effluents of poultry, pigs and… Abby Morrison: Okay. All right. So sorry,
I am on a roll now. So then, is that based off of what is already there in the sense of, oh, there’s a poultry farm there, so it’s reasonable that they would use poultry effluent there? Or is
It this would be nice if we could change all of these to dairy farms because the dairy effluent had the best results or how does that work? Patrick Durand: Maybe I can help for this. So indeed the setup of a model is based on the actual situation as
Detailed as possible, taking into account the data available in the area. And when we design the scenario, when we change the type of crops we sow, the type of cereals, et cetera, we take into account the consequences in terms of agricultural systems. For example,
If we increase the area of grassland and decrease the area of silage, maize, we will have less area to spread big flurry, for example. So we take that into account in the model, and at the end of this taking account all the consequences of the change we simulate,
Of course we obtain different type of farm. And the interesting thing in the consequences of these scenarios is that which is not what we expected, but in fact we tend to specialized the farms, which means in Brittany, many farms have both pigs and cows for example, or cows and poultry. And the
Result of the scenarios was we have to specialize the farm to be more efficient and to have consistent crop rotation for each. And the other consequence is that we were obliged to hypothesize an exportation of all the poultry effluence. We have no space more for poultry effluents,
So we can keep the poultry running, but we have to export the effluents if the scenario would be feasible. Abby Morrison: Okay. See, this is what I love about modeling work is because there is always that fine-tuning,
And I love being able to compare what the data says versus what is physically possible on the space or what is financially possible for the people that are actively living on. It may not be possible for every farmer to completely change their farm to fit the best model. And so it’s
Always fun for me to see how researchers approach those questions of what is most important to test, how detailed do we need to be? Do we need to split out between different types of effluent
Or not? Do we need to test these two types of one crop or can we just have an average number that we plug in? So I love those fine details, but as you have already mentioned some of the research
Results and I don’t want to spend too much time getting bogged down in the methods because I could certainly camp there for a very long time. Tell me more about your results and what you found. Patrick Durand: Well, the main message, most important
Results of study of this modeling exercise, it’s still possible to reduce further nitrate loads in this context, which was not completely evident because there has been a lot of regulation where the farmers have to comply to very strict rules to manage their nitrogen. But it’s still possible
To go further, but it’s not going to be easy. The first scenario, the scenarios of conversion will achieve something like 30% reduction of nitrogen loads in about five years. If we convert between five and 10% of catchment, which can be seen as not very much, but of course if a farm has most
Of his farming area in these bottom lines, it would be problematic for him to go on. So this is the first result. The second scenarios, so generalized change of agriculture would achieve the same reduction but only in 10 years. And with it would be more difficult, slower,
And especially the concentration in summer, which are the most problematic for the blooms, for the algae blooms would stay higher for a longer time. And if we go for the extreme scenario where we change, we get rid of all the agriculture and only put grassland, extensive grassland,
We would achieve a 50% reduction of nitrogen loads in 15 years, which means that we still have a very large nitrogen legacy in the soils and in the ground motors in this area. Which can be a little bit surprising because this is an area with relatively shallow soils and
Shallow groundwater system. It’s not an area with very deep and big groundwater bodies. So even in this type of system, we still have to account for a very large legacy of nitrogen. Indeed. And there is another bad news in our study, and it doesn’t come directly from our study, but we were
Doing this project with other scientists working on the modeling of all the algae specifically. And the result is even with 30% reduction of nitrogen loads, we are still in a situation where we can get our algae blooms not every year, but every three or four years and sometimes very
Large algae blooms. So if we really want to get rid of all these phenomena, either we have to get rid of agriculture, which is not an option because it’s one of the most productive area in Europe. So it would be problematic. But the other solution is to go for more radical changes,
Not staying in the same types of system but going into more agroecological systems, taking full use of ecosystem services of the soils and so on. Some of these systems are more or less known, but most of them needs to be developed in the future. And there is still a lot of research to
Go on on this type of situation. Abby Morrison: Sure. Okay. I have a question and if this is not something that you feel you have the expertise or just don’t want to go there, feel free to just veto the question. So you mentioned that if you
Were to convert some of the agricultural land into a managed grassland, if there was a farmer that was like, I’m the farmer on the coast, I’m the very bottom rung, does France have programs to be like, I’m sorry you can’t make money from farming that land, but here’s some kind of recompense
For you taking that out of production. Are there programs for that? Obviously in the United States, I don’t know a lot about how that works. Patrick Durand: No, in France we don’t have that neither because yes, farming is a private activity and you cannot
Forbid somebody to farm. We do have regulations, we do have programs of incentive to change the type of agriculture you made. And there is also another possibility which is, I don’t know if it’s really good news, but in France we are, like in most developed countries, we are losing a lot of
Farmers every year. So a lot of area is free. So we could imagine, but well, we are not in a very originative country, but we could imagine some kinds of land exchange between the farmers who
Want to go on and the farmers who quit. So there is still some degrees of freedom at this level and this is actually what the different policy makers are thinking about to implement right now. Abby Morrison: Sure, okay. Yeah, I was just curious
Because I don’t know a lot about how countries in Europe regulate that kind of thing or not. So you mentioned already that there is much research that can still be done on this topic and finding ways
To improve our status on this issue. So tell me more about what are the future research questions, whether that’s something you’re working on specifically or just in general? Wafa Malik: Yeah, so in the forthcoming steps,
We aim to couple the TNT2 model, the model that we used in this study, which calculates the nitrogen loads, reaching the coastal areas with a specialized ecological model designed for coastal ecosystem and specifically design it to estimate the proliferation of algae blooms. So this merge
Will provide us with the ability to simulate algae growth under the various scenarios that we have tested or explored and to have their impact on the algae bloom proliferation. And moreover, our future research goal will involve the co-design of the eutrophication management strategies and
The development of adaptive public policies. So it’s a collaborative effort that we bring together farmers, local authorities, stakeholders to design innovative strategies that strike a balance between environmental sustainability and agricultural productivity. It’s an exciting path forward toward more sustainable and harmonious coexistence of agriculture and environment.
Abby Morrison: I love that. Yeah. Balance coming up again. So man, I have the utmost respect for people, really fine-tuning those different balances in play. That’s incredible work. So thank you so much for your time already. I have three questions left
For you. The first one is, where can listeners go to learn more about this research? Patrick Durand: Well, of course we have several papers written about this because we developed the TNT2 model in the early 2000. So we
Still have quite a few papers on that. And more generally, if you Google coastal eutrophication, you will get a lot of internet resources about the question and specifically some website about Brittany problem. Some of them are in English, but of course most of them in French.
And there are even two movies and one comics made on this. So I don’t think they have been exported to other countries, but they will. I think since they have had some success, they will be available on the platform very soon. And more generally, our institute in Rennes, I’ve posted
A lot of resources about the relationship between agriculture and the environment in the French and European context. So yeah, I cannot point you to very specific resources, but it’s easy to find. Abby Morrison: Perfect. Yeah, we will include links to
Any of those that we can find in the show notes. Otherwise, happy hunting, everybody looking for those details. The next question is, if listeners want to take the next step to get involved with any of these things, what can they do? And that can be researchers who might be interested in
Doing this kind of research. It could be general public looking to interface with those public officials or just wanting to take measures to stop eutrophication in their own systems, anything like that. What would you suggest? Patrick Durand:
Well, for the general public, I would say that as we said, eutrophication and more generally environmental problem related to agriculture are very widespread nowadays. And to change that, we need to think about the way we are eating, the way we are buying food, the amount of money
We dedicate to alimentation, to food as compared to other more maybe less essential needs we have and the sort of thing we eat too, because it must be admitted. And it’s admitted now that a lot of problems come from intensive farming system. So probably if we want to solve this problem,
We need to eat less meat in our diet that will be good for the planet and that will be good for our health too. So this is for the general public, more specifically for the scientists, I think they have a role to play in this process, especially by designing innovative agricultural
Systems, not only based on technology because it’s not always possible to implement technology everywhere and it will cost resources. But also as I said in the designing system, more relying on the ecosystem functioning ecosystem services and some system actually
Many of them designed by farmers, by empirical knowledge can be quite productive. So I think there is a way to develop such cropping system more efficient and environmental friendly. But to do that, it’s probably necessary to get out of the laboratory and to make, as Wafa said,
Participatory research with farmers, with policy makers, with all the stakeholders, which is not easy because they have contending ideas and values and so on. So it’s not easy, but I think it’s necessary because it’s a nation’s essential problem of our planet nowadays. Abby Morrison: All right, that is
Some great advice for many types of people. I have one question left for you. What is one fun fact for each of you that listeners wouldn’t know if all they had was your research? Wafa Malik: Patrick, have something to say that discovered last year. Patrick Durand:
We have something in common, Wafa and I, but it’s not really completely common. It’s not completely common. We are both passionate dancers but not the same type of dance. I am a dedicated tango dancer, Argentine tango dancer, but I think it’s not the favorite dance for Wafa. And maybe she will say
More about that. Wafa Malik: So mine however is the Bachata dance. So I don’t know if… And this is what Patrick discovered last year when he invited me in his house and a party with his family and it was a kind of sort of
A game to do something and I choose to dance with my pair, the Bachata, and it didn’t take long for other guests to join us on the floor to dance. So it was cool. Yeah, and full of fun filled evening and memorable event. So thank you Patrick. Patrick Durand:
You’re welcome. Wafa Malik: I’m looking forward for the next invitation. Patrick Durand: It will come soon. Abby Morrison: Oh, I love that. Yeah. I’ve done a little bit of tango myself, but not Argentine. I wasn’t that far
Yet in my dance journey last I left off. But those are both wonderful dances, super fun. And what a fun fact that you are able to share that that’s delightful as has been this entire conversation. I have learned so much. I appreciate everything that you are doing to help Brittany and also
Other researchers dealing with similar issues. So thank you for your research and for your time. Wafa Malik: Thank you. Patrick Durand: You’re welcome. Thank you very much for you. Wafa Malik: I enjoyed it. Thank you. Abby Morrison: Good. Patrick Durand: Me too.
Abby Morrison: Thank you for listening to Field, Lab, Earth. This podcast is a joint production of the American Society of Agronomy, Crop Science Society of America, and Soil Science Society of America. More information can be found in the description below.