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Nitrogen is one of the most abundant elements in nature, making up 78% of the air we breathe, but it is not in the form that plants need to grow. The search for alternative forms of nitrogen, ready to be absorbed by plants, is essential to increase soil fertility and feed humanity as it approaches the 10 billion mark. The demand for nitrogen was so great in the 19th century that two wars were fought for control of some South American islands renowned for their abundant guano.
A process based on hydrocarbons
Then the Haber-Bosch process came along and satisfied the world‘s hunger for nitrogen by raising crops with an industrial process based on hydrocarbons. Since then, farming has become easier and fossil fuels have fed humanity. Without the two German chemists, it is estimated that almost 4 billion of us would not be in the world.
Over a century later, however, the problem of synthetic fertilizers is coming to a head: on the one hand they generate 2.5% of global greenhouse gas emissions (more than air transport) and on the other hand half of them are wasted, which instead of remaining in the fields ends up polluting the waters, causing algae blooms and gigantic dead zones in the world‘s seas. Furthermore, they make farmers dependent on oil giants such as UralChem or EuroChem and on petro-states such as Russia. To continue reliably feeding the world without burning it out would require another pair of scientists to find the Holy Grail of agriculture and give food plants the ability to self-fertilize.
The first studies more than 50 years ago
There are those who have been trying for decades, but for now we are not there yet. The only natural organisms capable of making nitrogen palatable for plants and animals are certain types of microbes, known as diazotrophs, which use molecular nitrogen in the air (N2) to produce ammonia (NH3), much better than the Haber process -Bosch and without any need for hydrocarbons. Recent developments in biotechnology, unimaginable in the days of Fritz Haber and Carl Bosch, suggest the possibility of extracting the mechanisms used by these bacteria to fix nitrogen and inserting them into plants. This way, one day we may have plants that can fertilize themselves.
The first experiments on yeast maybe in a couple of years
The pioneers of this research are two British scientists, Ray Dixon and John Postgate (who has since passed away), who in 1972 published an article in Nature in which they reported having induced E. coli, a bacterial species that normally does not fix nitrogen, to do so by importing the genes of another bacterial species. At the time, rapid progress towards plants seemed imminent, but in reality the biotechnological tools for the great leap from bacteria to the plant world have only been developed in the last decade. In addition to Dixon, many are working on it today, starting with Luis Rubio, director of the Center for Plant Biotechnology at the Polytechnic University of Madrid, also financed by the Gates Foundation. Rubio and his teams are trying to make nitrogenase work outside of its bacterial home, the first step in inserting it into the genome of food plants. The idea is to first implant nitrogenase in a yeast, perhaps in a couple of years, then in the guinea pig plant par excellence, tobacco, and finally in rice. Going from yeast to actual food crops could take more than a decade.