The world has a big fertiliser problem. Here’s how to fix it
What was the most significant scientific breakthrough of the 20th century? You might say the invention of computers, the discovery of nuclear fusion or the DNA double helix. But one oft-overlooked technological breakthrough has arguably done more to support human life than nearly any other.
In the early 20th century, a pair of German chemists figured out how to take nitrogen from the air and use it to produce ammonia. This ammonia could in turn be used to make fertilisers, replacing natural fertilisers such as guano manure created by bird and bat poo. Nitrogen is an essential nutrient for plants to make protein, and synthetic fertilisers have had an incredible impact on our ability to feed people. It is estimated that half of the current global population is supported by crops grown with synthetic nitrogen fertilisers.
But these fertilisers are also extremely bad news for both the climate and the local environment. What if we could replace them with something better? One solution being developed by several companies is new technologies which add nitrogen-fixing microbes to the soil to increase the amount of nitrogen available to plants, reducing the need for synthetic nitrogen.
Nitrogen fertilisers come with a heavy environmental cost. The industry is energy intensive, accounting for between one and three per cent of greenhouse gas emissions – above any other industrial chemical process. Fixing nitrogen uses so much natural gas that when gas prices recently spiked in the UK, fertiliser producers opted to shut-up shop for a while rather than carry on making ammonia. The large bulk volume of fertiliser also makes it energy intensive to transport to farmers.
When added to fields, nitrogen also leads to microbial reactions that generate nitrous oxide emissions, a greenhouse gas with around 300 times the warming potential of CO2, resulting in a whopping 4.1 per cent of greenhouse gas emissions. Agricultural runoff from nitrogen fertiliser can also lead to “dead zones” with major environmental issues, such as huge damages to fisheries and marine habitats.
One solution to these problems could be to find new ways to fix nitrogen directly in the fields, thus reducing the amount of synthetic fertiliser needed, or even bypassing the need for them completely.
This is the focus of Leaps, the impact investment arm of German multinational pharmaceutical and crop science firm Bayer. Leaps has now invested in three companies developing this kind of technology.
The first, Sound Agriculture, is a spray applied to the field when plants most need nitrogen. It works by activating microbes in the soil that fix nitrogen from the air. “Their technology basically helps plants recruit the microbes,” says Derek Norman, vice president of venture investments at Leaps.
The second technology, Microprime from California based start-up Andes, applies natural microbes to seeds. These microbes then fix nitrogen directly alongside the plant roots as it grows. “All plants naturally have microbes associated with them,” says Norman. “Through treating seeds with microbes, you can give [those] microbes a head start and put the microbes you want on the plant”. The technology is currently in field trials but could be on the market next year.
Another company leaps is investing in, Joyn Bio, has a different approach. Its focus is on genetically engineering microbes to maximise their ability to fix nitrogen. “That's a very difficult reaction,” says Norman. “Nitrogen is one of the most stable compounds, it's got a triple bond, it takes a lot of energy to break that bond. So it actually requires some very difficult biology for microbes to be able to break those bonds and convert it to a form that plants can use.”
“It is very important not to get into a mindset of a
silver bullet solution”
While precise numbers are not available, trials of these technologies tend to show the potential to reduce by the use of synthetic fertilisers by around a third, says Norman. He believes these biological solutions will play a key role in reducing synthetic nitrogen use, although deploying them across the globe’s vast expanses of farmland will clearly take some effort. In the longer term, these kinds of technologies could potentially completely replace synthetic nitrogen fertilisers, he adds. Crops could even be engineered to fix and produce nitrogen themselves, something some researchers are already working on. “That would be very technically challenging, but a lot of the researchers in the field are very interested in that kind of solution,” he says. (Of course, some legumes already do fix nitrogen, a reason why they are used as cover crops in some farming systems to add nitrogen to soils.)
Norman says he would expect all of these nitrogen fixation solutions to “at least be comparable in cost” to applying synthetic nitrogen. The evolution of carbon markets in agriculture could also make these kinds of solutions increasingly attractive for growers, he adds.
Despite the potential for lower synthetic fertiliser use, there is still a question of how much such technologies address the nitrous oxide pollution coming directly from the fields, a huge piece of the footprint of agriculture, says Marcia DeLonge, an expert in food and the environment at the Union of Concerned Scientists (UCS).
Norman says the secondary effects of nitrogen fertiliser, such as nitrate runoff, will also likely be reduced due to the lower synthetic nitrogen application, although testing would need to be done to verify this. “The plants are getting exactly what they need, versus putting it down across a whole field, much of which is never even utilised by the plants,” he says.
There are, of course, other ways to reduce the use of synthetic fertilisers. Slow-release fertilisers are one option; another is to add fertilisers to fields in a more targeted way, says DeLonge. Farmers often apply far more synthetic fertiliser than they actually need. One 2019 study found farmers in Iowa watersheds were applying double the recommended rates on their corn. “I think a lot of farmers are incentivised to err on the side of applying more, because yield is so responsive to nitrogen,” says DeLonge. There are opportunities to address this though, she says, such as by giving farmers more information or better guidance on exactly where and exactly when to apply fertilisers.
There are also other, time-tested ways to bring more nitrogen into soils, like the use of cover crops (such as nitrogen-fixing legumes planted to cover the soil in the off season) and crop rotation (growing a bigger variety of different crops on the same soil). “These also provide other benefits in terms of building soil health, bringing more carbon into soils and keeping soils covered for more of the year, and keeping living roots in the ground for more of the year,” says DeLonge, noting that they can also help build more resilient farming in the face of climate impacts.
Technology can help make these solutions more readily available, such as by supporting farmers to track and manage these systems, adds DeLonge. “It is very important not to get into a mindset of a silver bullet solution, or to lose sight of some of the really valuable practices that have been known about for a long time, and that are currently being used very effectively in some spaces, but really are vastly underrepresented. There's a lot of evidence pointing to the importance of expanding them.”
Which other climate solutions would you like to see in future editions of Chasing Zero? Send your thoughts to [email protected] or find me on Twitter @jloistf
Keep chasing,
Jocelyn Timperley
In the early 20th century, a pair of German chemists figured out how to take nitrogen from the air and use it to produce ammonia. This ammonia could in turn be used to make fertilisers, replacing natural fertilisers such as guano manure created by bird and bat poo. Nitrogen is an essential nutrient for plants to make protein, and synthetic fertilisers have had an incredible impact on our ability to feed people. It is estimated that half of the current global population is supported by crops grown with synthetic nitrogen fertilisers.
But these fertilisers are also extremely bad news for both the climate and the local environment. What if we could replace them with something better? One solution being developed by several companies is new technologies which add nitrogen-fixing microbes to the soil to increase the amount of nitrogen available to plants, reducing the need for synthetic nitrogen.
Nitrogen fertilisers come with a heavy environmental cost. The industry is energy intensive, accounting for between one and three per cent of greenhouse gas emissions – above any other industrial chemical process. Fixing nitrogen uses so much natural gas that when gas prices recently spiked in the UK, fertiliser producers opted to shut-up shop for a while rather than carry on making ammonia. The large bulk volume of fertiliser also makes it energy intensive to transport to farmers.
When added to fields, nitrogen also leads to microbial reactions that generate nitrous oxide emissions, a greenhouse gas with around 300 times the warming potential of CO2, resulting in a whopping 4.1 per cent of greenhouse gas emissions. Agricultural runoff from nitrogen fertiliser can also lead to “dead zones” with major environmental issues, such as huge damages to fisheries and marine habitats.
One solution to these problems could be to find new ways to fix nitrogen directly in the fields, thus reducing the amount of synthetic fertiliser needed, or even bypassing the need for them completely.
This is the focus of Leaps, the impact investment arm of German multinational pharmaceutical and crop science firm Bayer. Leaps has now invested in three companies developing this kind of technology.
The first, Sound Agriculture, is a spray applied to the field when plants most need nitrogen. It works by activating microbes in the soil that fix nitrogen from the air. “Their technology basically helps plants recruit the microbes,” says Derek Norman, vice president of venture investments at Leaps.
The second technology, Microprime from California based start-up Andes, applies natural microbes to seeds. These microbes then fix nitrogen directly alongside the plant roots as it grows. “All plants naturally have microbes associated with them,” says Norman. “Through treating seeds with microbes, you can give [those] microbes a head start and put the microbes you want on the plant”. The technology is currently in field trials but could be on the market next year.
Another company leaps is investing in, Joyn Bio, has a different approach. Its focus is on genetically engineering microbes to maximise their ability to fix nitrogen. “That's a very difficult reaction,” says Norman. “Nitrogen is one of the most stable compounds, it's got a triple bond, it takes a lot of energy to break that bond. So it actually requires some very difficult biology for microbes to be able to break those bonds and convert it to a form that plants can use.”
silver bullet solution”
Norman says he would expect all of these nitrogen fixation solutions to “at least be comparable in cost” to applying synthetic nitrogen. The evolution of carbon markets in agriculture could also make these kinds of solutions increasingly attractive for growers, he adds.
Despite the potential for lower synthetic fertiliser use, there is still a question of how much such technologies address the nitrous oxide pollution coming directly from the fields, a huge piece of the footprint of agriculture, says Marcia DeLonge, an expert in food and the environment at the Union of Concerned Scientists (UCS).
Norman says the secondary effects of nitrogen fertiliser, such as nitrate runoff, will also likely be reduced due to the lower synthetic nitrogen application, although testing would need to be done to verify this. “The plants are getting exactly what they need, versus putting it down across a whole field, much of which is never even utilised by the plants,” he says.
There are, of course, other ways to reduce the use of synthetic fertilisers. Slow-release fertilisers are one option; another is to add fertilisers to fields in a more targeted way, says DeLonge. Farmers often apply far more synthetic fertiliser than they actually need. One 2019 study found farmers in Iowa watersheds were applying double the recommended rates on their corn. “I think a lot of farmers are incentivised to err on the side of applying more, because yield is so responsive to nitrogen,” says DeLonge. There are opportunities to address this though, she says, such as by giving farmers more information or better guidance on exactly where and exactly when to apply fertilisers.
There are also other, time-tested ways to bring more nitrogen into soils, like the use of cover crops (such as nitrogen-fixing legumes planted to cover the soil in the off season) and crop rotation (growing a bigger variety of different crops on the same soil). “These also provide other benefits in terms of building soil health, bringing more carbon into soils and keeping soils covered for more of the year, and keeping living roots in the ground for more of the year,” says DeLonge, noting that they can also help build more resilient farming in the face of climate impacts.
Technology can help make these solutions more readily available, such as by supporting farmers to track and manage these systems, adds DeLonge. “It is very important not to get into a mindset of a silver bullet solution, or to lose sight of some of the really valuable practices that have been known about for a long time, and that are currently being used very effectively in some spaces, but really are vastly underrepresented. There's a lot of evidence pointing to the importance of expanding them.”
Keep chasing,
Jocelyn Timperley
