All things agriculture: nitrogen pollution, soil degradation, methane emissions and alternatives

— Anh NGUYEN

That’s a mouthful title. A shorter title would be “industrial agriculture: bad practices and alternatives”. Yet, the word “bad” is subjective and I would prefer to talk about agriculture and industrial agriculture in a more objective way. 

So, there are a couple of facts:

• The agricultural revolutions (the first one circa 10,000 BC, but especially later ones from the 8th to the 13th century in the Islamic region, from the 17th to 19th century in Britain and the Green Revolution from the 1930s to 1960s) had greatly altered human living conditions and human ways of life. We learned to sow and reap, we settled down in villages and cities, and the human population is on the rise after the Black Death (14th century). 

• The world’s population today is 8 billion people, projected to be 9,7 billion in 2050. The growth rate is ever-decreasing, but the population is still on an upward trend. 

The explosion of the human population is correlated with medical advancements and agricultural productivity. The more advanced technologies we have, the more human lives we can nurture and secure. Yet the more human lives there are, the more food we have to produce. According to Food and Agriculture Organization (FAO), enough food has been produced today to feed everyone on the planet, yet there are still 821 million people considered to be “chronically undernourished”. 

The question now is: Can we produce enough food in a sustainable way for 8 billion people?

Before trying to answer that question, we will take a look at the impacts of the Green Revolution and industrial agriculture on the planet’s ecosystems. 

Nitrogen pollution and excessive use of synthetic fertilizers

That is also a mouthful title. But it all has to do with a rather familiar process: plant growth. 

To grow a plant, you need water, the Sun, CO2 (for its photosynthesis), nutrients and minerals from the soil such as nitrogen (N), phosphorus (P) and potassium (K).

Regarding nitrogen, there are two natural processes in which plants can “get” these nitrogen compounds that they use to grow: 

• First, lightning helps recombine the atoms in nitrogen gas and oxygen gas in the atmosphere (78% of the Earth’s atmosphere is nitrogen, 21% is oxygen) to form nitrate (NO₃). 
  This nitrate falls to the surface of the Earth through the rain and into the soil. The plant “takes” this nitrate in the soil to grow.

• Second, nitrogen gas (N₂) in the atmosphere diffuses into the soil, where some magical nitrogen-fixing bacteria in the soil convert it into ammonium ions (NH₄⁺), which can be used by plants. 
  Some plants do a better job fixing nitrogen in the atmosphere than others. For example, legumes, such as clover and lupins, are often grown by farmers because “they have nodules on their roots that contain nitrogen-fixing bacteria”.

To increase agricultural productivity in an industrial model, the common practice is to put more synthetic fertilizers of nitrate (NO₃) and ammonium (NH₄) into the soil. “That shouldn’t be a problem”, you said. “Anyhow plants need these to grow, don’t they? And the more the merrier, isn’t it?”

No, there is a limit to what plants can take because plants cannot take up nitrate continuously, and excess nitrate is actually toxic to the plants. Worse, this excess nitrate becomes dangerous because: 

• First, it is leached away into the soil and in water and into the sea. 
  High levels of nitrate in drinking water can affect how our blood carries oxygen or cause birth defects or thyroid disease. 
  High levels of nitrate leaked into the sea can cause the bloom of toxic green algae. For instance, in Brittany (France), excess nitrogen from intensive agriculture in the region goes to the sea untreated, and then the green algae feed on this under the sun, creating a mattress of hydrogen sulphide (H2S). This H2S gas causes people and animals to fall ill and suffocates fish and other marine creatures living under it. 

• Second, some soil organisms convert the excess nitrate to the greenhouse gas nitrous oxide (N2O). N2O is the most important greenhouse gas after methane and carbon dioxide and the biggest human-related threat to the ozone layer. It is over 300 times more effective at trapping heat in the atmosphere than the famous CO2. 
  This N2O gas can also cause acid rain when meeting sulfur dioxide (SO2) that comes from the burning of fossil fuels and the smelting of mineral ores. 

Alright, the situation is quite depressing, isn’t it? All of this nitrogen problem leads us to a couple of questions:

• First, can we live without synthetic fertilizers? After all, plants have been growing well before humans invented synthetic fertilizers, right?
• Second, why can’t we just put the “right” amount of synthetic fertilizers instead of too much in the first place? Also, what is even the right amount?

Regarding the first question about the role of synthetic fertilizers, here’s an interesting graph, showing the world population supported by synthetic fertilizers. It is estimated that synthetic nitrogen fertilizers have supported 42% of global births over the past century.

Synthetic nitrogen fertilizers enable the lives of about four billion people, who otherwise would have died prematurely or have never been born at all. The world cannot feed these four billion people without synthetic nitrogen fertilizers – at least not right now. 

But the world also uses too much of it: about 50% of applied nitrogen is lost to the environment, through the processes listed above. And that’s just about nitrogen. 50% of phosphorous is also lost to the environment. 

Why all of this waste? Is there a formula to calculate the right amount of synthetic fertilizers to put into our cropland?

Sadly no. It depends a lot on what we called the “nitrogen footprint” of each country and region. To combat nitrogen pollution, solutions must be designed based on these particularities. 

In this article on The Conversation, researchers suggest that we eat lower nitrogen footprint protein diets, such as vegetables, chicken and seafood (beware of the overfishing problem though), rather than high nitrogen footprint protein food such as beef and lamb. 

“Why beef and lamb?”, you ask, “are they fed on synthetic fertilizers too?” Technically no, but indirectly yes. The majority of our agricultural land is used for food that is not directly for us humans to eat, but for our livestock (which we will eventually eat): nearly 60% of the world’s agricultural land is used for beef production, and livestock in total takes up nearly 80% of global agricultural land. 

Another solution is to transition gradually to organic fertilizers (i.e., meat processing waste or animal manure) and composts. In Europe, for example, organic foods mean no use of pesticides and synthetic fertilizers; farmers use organic fertilizers and composts instead. Indeed, this is a transition and not an overnight shift. Remember: 4 billion people still depend on synthetic fertilizers to survive (unless you approve the Thanos approach). 

One inconvenience with organic fertilizers, some argue, is that they are still sourced from intensive meat farming, dependent on animal waste. Yet, this shortcoming still cannot be compared to the direct consequences of synthetic fertilizers such as nitrogen pollution. 

Soil degradation

There are many causes of soil degradation, such as agricultural mismanagement (e.g. the nitrogen pollution we just discussed, or the overuse of pesticides and the practice of monoculture), land clearance (e.g clearcutting and deforestation), inappropriate irrigation, loss of arable land due to urban expansion, livestock overgrazing and so on. Long-term climatic changes can also cause soil degradation. 

“So what?”, you ask, “Things degrade. Entropy in the universe will only increase, and all good things come to an end, what is new?” The news is that there are eight billion people to feed, and we depend on arable lands, as well as good soil health and thriving biodiversity in order to survive. Besides, soil degradation can lead to environmental disasters such as floods (e.g. the 2022 Pakistan floods that killed more than 1000 people), or mass migration and conflicts. More than 75% of Earth’s land areas are substantially degraded (2018). By 2050, more than 90% could become degraded if no measure is taken. This could lead to mass migration and conflicts, as first seen in the Arab Spring in 2010-2012). 

The better question to ask is: What do we do to reverse this soil degradation trend?

To find a solution, we must first look at the causes. Though we won’t have time to go into detail about all causes mentioned earlier in the section, we can zoom in on agricultural mismanagement, with the overuse of pesticides, and monoculture. 

The first victim of pesticides, sadly, is their direct users – farmers. Take China for example: the biggest user of pesticides with more than 12kg of pesticide per hectare. Every year, more than 225 million farmers in China are poisoned by pesticides. 

Is it possible to reduce the use of pesticides and still secure our food production? Is it possible to ban pesticides altogether? 

In Europe, the European Commission is working towards a strategy to reduce half of pesticide use by 2030. In 2022, the EU also issued a joint statement to ban all exports of banned chemicals and pesticides in the EU. That is, EU members cannot sell pesticides that have been banned in the EU to countries where these pesticides are still in legal use. Take the “Don’t do unto others what you don’t want done unto you” to another level. The UK, however, is still by far “Europe’s biggest exporter of toxic banned pesticides to poorer countries” with “13,760 tonnes of shipments to low- and middle-income countries”. 

Not just in developing countries, it is not that simple to ban pesticides anywhere in the world. Take the US for example, many farmers objected to the ban on Chlorpyrifos in 2021, arguing that it is “a vital tool in farming”—and without it, yields could drop around 45%. 

Why are pesticides a vital tool in farming? The practice of monoculture (i.e. growing one crop species in a field at a time) and intensive farming in the US has pushed agricultural production to a fragile situation. Monoculture crops are “more likely to be affected by blight or pests”, as they can move faster to an extended area, now with reduced biodiversity and resilience. Farmers then must apply more pesticides, which again reduces the biodiversity level and resilience. And this spirals down. 

Again, there is no possible overnight shift. Regarding developed countries, there must be a transition towards practices such as polyculture or intercropping, with two or more species intermingled in a field. One species can be “specialised” in fixing nitrogen in order to be less dependent on synthetic nitrogen fertilizers. A research paper from The Pennsylvania State University has shown that polyculture can both reduce pest abundance and increase crop productivity. 

As for developing countries, the lack of “rigorous regulations to control pesticides as well as training programs for personnel” is the main concern. Many of these countries in Eastern Europe, Central Asia or Africa still have major stocks of obsolete pesticides and chemicals. Beyond pesticides and strict control of pesticides, other possible alternatives for developing countries to fight against pests and secure agricultural production could be biological pest control (i.e controlling pests with their natural predators or parasites) or polyculture and intercropping. 

Agroecology or pesticide-free agriculture are alternatives that have gained much traction in the last decade. Scientific evidence has been proven, and a large-scale experiment is to be done. The major game-changer here would be policymakers, who could either facilitate this transition towards more sustainable farming practices – or keep things as they are.

Methane emissions

Dear readers, before we continue, please take a little break with a cool glass of water. 

Good to go? Alright! Let’s talk about methane gas, the second most important greenhouse gas contributing to climate change, just after carbon dioxide. Methane is responsible for around 30% of the current rise in global temperature. 

In nature, methane gas (CH4) is produced by living organisms (plants, animals…) under the effect of fermentation, digestion, decomposition or decay. About a third of total methane emissions come from wetlands, for example. This type of habitat is filled with waterlogged soils and permafrost (i.e a ground that remains frozen for at least two consecutive years, with essentially a mixture of rock, soil, sediment, ice, and organic material). 

Wetlands are important carbon sinks, but with a warming climate that causes wetland soils to warm or flood, carbon and methane are released into the atmosphere. The process is explained here: 

“Alright, that’s good to know that there are methane bombs ticking away in wetlands and from the permafrost thaw… But how does any of this have anything to do with agriculture?”, you ask. 

When it comes to methane gas directly emitted by human activities (60% of methane global emissions), fossil fuels, livestock and landfills come in as the first contributors (cf. photo).

How can our cattle produce methane anyway? 

Here’s how:

• Cows, sheep, goats (and giraffes!) are part of a group of animals called Ruminants (which comes from the Latin ruminare, which means ‘to chew over again’).
• Food comes into their body. In their four stomachs, there is a process called enteric fermentation, in which “bacteria break down complex carbohydrates into simple sugars”. This process also produces CO2 and methane (CH4). 
• These gases come out of the body of the cattle, and are released into the atmosphere.

Sure enough, a couple of cows cannot warm up our planet. But there are 1.5 billion cows across the globe, and in 2021, there was 2.81 million head slaughtered for food. Things can add up quite quickly. 

However, it is also important to stress that tackling the methane emissions of our burping cows and sheep is just one of the levers to reduce greenhouse gas and negative environmental impacts. If you read up to this part, you have certainly come to understand that there can’t be one single, magical solution that will drastically cut off our emissions. Instead, there should be a mix of plausible and effective solutions, while taking into account the possible negative externalities. 

There are a couple of alternatives to reduce methane emissions from cattle: 

• Make the cows emit less methane gas:
  • digesting hay and grass produces more methane than corn. However, cows are not supposed to eat corn or cereals. Eating these will lead to bloat and acidosis, and this leads to the (over)use of antibiotics which will leak into the environment. 
  • digesting new things such as seaweeds, which cut emissions in half (except that cows don’t really like the salty taste of seaweeds. Hello Captain obvious!).
• A more serious alternative would be to reduce our red meat consumption (this should also help reduce animal suffering due to massive meat farming) and replace it with plant-based proteins, which have a lower methane footprint (and water and nitrogen footprint). 

Conclusion

As you have seen, agriculture has done wonders – enabling modern human lives, and damages – wreaking havoc on the biosphere and its ecosystems. Yet, there is no time left for us to be pessimistic.

As mentioned before, more sustainable agricultural practices such as agroecology, regenerative agriculture, permaculture, small-scale farming etc. must be studied, experimented and scaled up in order to feed 8 billion people without crossing the planetary boundaries.

Indeed, there is no silver-bullet, simplistic solution to complex problems such as climate change, biodiversity loss and environmental degradation. Humanity must find an optimal combination of solutions. This is not at all an easy task, but a task worth tackling and pondering over if humanity would ever wish to become a better version of itself.

*** Bonus: 

Here are some of the most mind-blowing points that I’ve drawn from the book “Who Really Feeds the World?: The Failures of Agribusiness and the Promise of Agroecology” by Vandana Shiva, an Indian scholar and environmental activist. 

1. Small-scale farmers feed the world, not large-scale industrial farms️

• “Local farming communities still produce 70% of the world’s food”
• “In an ecological and small farming system, outputs include the rejuvenation of ecological processes, the diverse outputs of crops, livestock and trees, and the livelihoods created through co-creation and co-production. In a large-scale industrial farming system, output is reduced to a single community and input is reduced to labour.”
• “The devaluing of livelihoods is also a recipe for further intensifying the external inputs of chemicals and fossil fuels, which rather than feeding people and sustaining farming systems, create hunger and generate environmental degradation. 
• This is known as the “myth of more”, in which an agricultural system where a farmer spends more for costs of inputs than she or he will earn from selling a monoculture community is presented as “productive”, a path to higher incomes and higher production.”

2. Seed freedom feeds the world, not seed dictatorship

• “In the last half century, a reductionist, the mechanistic paradigm has laid down the legal and economic framework for privatizing seeds and the knowledge of seeds. This has destroyed diversity, denied farmers’ innovation and breeding rights, enclosed the biological and intellectual commons through patents, and created seed monopolies.”
• “Globally, more than 1.4 billion people depend on farm-saved seed as their primary seed source. In order for agribusinesses to make profits, they must rupture this self-sustaining, nutritious system of food production. Farmers’ varieties are therefore being replaced by 3 new seed varieties: high-yielding varieties, hybrid seeds, and GMOs.”
• The lawsuits between Monsanto vs Vernon Hugh Bowman (2007), and Monsanto vs Percy Schmeiser (1998).
• Their consequences: “Monsanto and other corporations can own all future generations of seeds, and they can use patents to sue farmers whose crops it has contaminated.”
• “Since 1995, 284 000 farmers in India have killed themselves due to rising input prices and volatile output prices.”

3. Localization feeds the world, not globalization️

• As far as “cheap food” goes, globalized food is actually produced at a very high cost, and if it weren’t for the fact that agribusinesses collect more than $400 billion in subsidies in rich countries, the entire system would collapse.”
• “The subsidized commodities are then in turn sold to poor countries, which are forced to dismantle their border protections so that rich nations can “dump” artificially cheap commodities into the developing world. […] This creates the artificial impression that cheaper goods are now available in poorer countries. However, what this actually does is destroy local sources of food production and distribution, including farmers’ livelihoods.” (e.g. Kenya in 1980 with trade liberalization, Mexico in 2014 with North American Free Trade Agreement – NAFTA)
• “One billion people on the planet are hungry (2009). Globalization has led to a shift from “food first” to “export first”, in which growing luxury crops for export takes precedence over growing food crops for people.”
• “Ironically, while one in every four Indians goes hungry due to the displacement of local food sources and farmers’ livelihoods, an urban upper class is suffering from diabetes and obesity, which stem from exactly the same source”.