When decoupling the roots of our climate crisis, carbon dioxide (CO2) emissions from industry and methane (CH4) emissions from animal agriculture garner the bulk of the attention. But for years, scientists have warned about a lesser-discussed greenhouse gas posing problems for our planet: nitrous oxide (N₂O).
While N₂O accounts for a mere 6.5 percent of US emissions, it touts 300x the warming power of CO2. It also traps heat in the atmosphere for an average of 114 years before being destroyed by chemical processes (nearly 10x the duration of CH4). Even though N₂O has always existed in the atmosphere - mainly produced via microbial processes in the soil - human activities account for more than 50 percent of the problem. In the US, 74 percent of N₂O emissions are driven by increases in synthetic fertilizer use.
Since the 1960s, in the US alone, the use of nitrogen applied to farmland in the form of synthetic N fertilizers has risen more than 300 percent, even though the amount of cropland has stayed constant. Roughly half of the nutrient spread gets taken up by plants to supplement soil nitrogen. The remainder of the fertilizer is lost to the environment through volatilization and leaching, entering the air as N₂O or seeping into groundwater - stimulating massive algae blooms that create dead zones beneath the surface.
The root cause
Three nutrients decide the fate of young plants: Nitrogen (N), phosphorous (P), and potassium (K). Nitrogen, in particular, is one of Earth’s most abundant resources - comprising 78 percent of the air we breathe. Yet, unlike CO2 or oxygen, it is just out of reach of plants without fixation into chemical compounds like ammonia, which forms when a nitrogen atom combines with three hydrogen atoms.
Thus, some 100 years ago, when humanity faced global starvation, two scientists developed the Haber-Bosch process, an invention by which atmospheric nitrogen is captured and combined with hydrogen derived from natural gas or coal to mass-produce ammonia. Ammonia is now the second-most commonly produced chemical. Used in vast quantities to synthesize artificial N fertilizers that help grow nearly half of the world’s food production.
The largest Haber-Bosch factories require pipelines to traverse the compound directly from Texas plants to Iowa cornfields. And while the process uses 4x less energy per ton of fertilizer than it did in the early days, it still consumes 2 percent of the world's total annual energy supply - a bulk of which comes from burning fossil fuels - to create the heat and pressure necessary for production.
Monolith Corp is one of the most ambitious projects striving to produce carbon-free ammonia by utilizing proprietary clean hydrogen. While making the existing Haber-Bosch process “greener” presents a more sustainable way to feed the world, it isn’t a cure-all. Moreover, the skyrocketing price of Ammonia is creating the tailwinds for a fertilizer revolution.
Pathways to fixing nitrogen to fix nitrogen, better:
Change the process: In 2018, the synthetic fertilizer supply chain emitted 1,250 million tonnes of CO2e, equivalent to 21.5 percent of the annual direct emissions from agriculture. Liquium is creating small-scale ammonia plants that operate at low temperatures and normal atmospheric conditions to avoid the GHG emissions stemming from burning fossil fuels during manufacture. Meanwhile, Nitricity produces on-farm nitrogen fertilizer with only air, water, and renewable electricity.
Change the protocol: To avoid the doubling of N₂O emissions by 2050, we must therefore move away from ‘spray & pray’ tactics and towards methods that help us use less synthetic fertilizer without sacrificing crop yields. Farmers now have access to Granular Ag’s remote sensing capabilities or Arable’s in-field IoT sensors to monitor nutrient absorption by plants and make more informed nitrogen application decisions on an acre-by-acre basis.
Change the input: Unlike synthetic fertilizers, natural biofertilizers slowly release nitrogen - ensuring that the nutrient is available to plants only when they need it, resulting in less runoff. In recent years, new “biological” input companies such as Kula Bio and Joyn Bio have also leveraged consortiums (two or more bacterial groups living symbiotically) or selected species of beneficial microbes to convert nitrogen from the air to a form that plants can use.
Change the system: US row crops (i.e., corn, soy, and wheat) soak up 12 percent of the global synthetic fertilizer supply. While it is unlikely that the agricultural sector will ever completely abstain from fertilizers, The momentum behind regenerative techniques presents an opportunity to re-orient our approach to farming from one that emphasizes chemicals to one that emphasizes biology.
Where to from here
Beyond scientific breakthroughs, many hardworking farmers' are reluctant to curb their synthetic fertilizer use out of fear it will decrease yields and profitability. Yet the data supports the opposite conclusion; synthetic inputs deplete soil quality and organic matter over time, forcing farmers to pour their thin profit margins into higher and higher doses.
In the long run, growers can increase profits and reduce emissions by managing agroecosystems through regenerative practices. ReGen Ventures is excited to see solutions displacing synthetic N fertilizer across a range of crops, soils, and climates. Solving our N₂O problem will only happen if new technologies offer farmers a pathway to improve land productivity and their bottom line.