Researchers have calculated that two-thirds of fertilizer emissions occur after the fertilizer is sprayed on fields, with the remaining third of emissions coming from industrial operations, according to the study.
According to the report, researchers from the University of Cambridge in the UK have calculated the carbon footprint over the entire life cycle of fertilizers. This is the first time that fertilizers have been precisely estimated to be responsible for 5% of global greenhouse gas emissions. Carbon emissions could be cut to one-fifth of current levels by 2050.
Although nitrogen-based fertilizers are already recognized as a significant contributor to greenhouse gas emissions, the study noted that this is the first time their complete contribution, from manufacture to application, has been comprehensively measured.
According to their estimate, manure and synthetic fertilizers emit the equivalent of 2.6 gigatonnes of carbon annually, which is more than what worldwide aviation and shipping do together. The study concluded that although there is an urgent need to cut carbon emissions from fertilizers, this must be balanced with the requirement for global food security.
The paper notes that previous studies have predicted that 48% of the world's population is fed by crops grown with synthetic fertilizers and that the population will increase by 20% by 2050. According to Cambridge researchers, to cut fertilizer emissions while preserving food security, a mix of scalable technology and regulatory solutions is required.
The emissions from manure and synthetic fertilizers may, however, be cut by as much as 80%, to one-fifth of current levels, without a loss in productivity, according to their estimates, provided such solutions could be applied at scale. The journal Nature Food reports the findings.
Fertilizers are one of the two primary products of the petrochemical sector, and Serrenho and his co-author Yunhu Gao set out to precisely assess their overall effects.
According to the survey, plastics and fertilizers make up the vast bulk of all petrochemical industry products—up to 74%—in total. We must identify and prioritize any interventions we can create to make fertilizers less hazardous to the environment to minimize emissions, according to Serrenho.
By balancing the production and consumption of nitrogen fertilizers with regional emission factors throughout nine geographical regions, the researchers were able to map the global flows of manure and synthetic fertilizers as well as their emissions for 2019, along all phases of their lifespan.
"But only after quantifying all emissions, at every point of the lifecycle, can we then start looking at different mitigation methods to reduce emissions without a loss of productivity," said Serrenho.
The greatest theoretical impact of several mitigation strategies was enumerated and measured by the researchers. Although most of these strategies are well known, their maximum potential impact had not been determined.
Ammonia synthesis accounts for the majority of emissions from the manufacture of synthetic fertilizers, which are also a result of some of the chemical processes involved. The industry's decarbonization of heating and hydrogen production would be the most efficient mitigation at the production stage.
Additionally, fertilizers may be combined with substances known as nitrification inhibitors, which stop bacteria from producing nitrous oxide. However, it is likely that these compounds will increase the cost of fertilizers.
According to Serrenho, there must be some type of financial incentive for farmers and fertilizer firms if fertilizers are going to be more expensive. Farmers are currently not compensated for creating lower emissions, which makes farming a very difficult business, according to Serrenho.
However, reducing the amount of fertilizers we use would be the most efficient strategy to lower emissions linked to fertilizer use. Serrenho declared, "Our usage of fertilizers is terribly inefficient.”
Because of farming practices, we use much more than we need, which is economically unproductive. Serrenho stated, "If we applied fertilizer more effectively, we would require a lot less fertilizer, reducing emissions without impacting crop output."
