Cereals are in much of the food we eat every day: in the bread we eat for breakfast, in the pasta we eat for lunch and in the cookies we eat for snacks. But what few people know is that their quality and sustainability depend on an invisible battle that takes place underground. In this story, the protagonists are soil microorganisms and fertilizers, whose balance can make the difference between a bountiful crop and an ecosystem in crisis.

Fertilizers: heroes or villains?
For decades, fertilizers have been the core topic for feeding a growing population. Thanks to them, cereals have achieved extraordinary yields, guaranteeing food supply. But their excessive use has had worrying consequences: water pollution, greenhouse gas emissions and loss of natural soil fertility.

That is why science is looking for new strategies to optimize the use of fertilizers without harming the environment. And that is where soil microorganisms come into play.

The invisible allies of agriculture
Beneath our feet, in every handful of soil, there are millions of different microorganisms working tirelessly.

Some, such as Rhizobium and Azospirillum bacteria, perform extremely difficult and unusual activities such as capturing nitrogen present in the air and converting it into a mineral nutrient that plants can use for growth. Others, such as mycorrhizal fungi, create subway networks that help roots absorb water and minerals and even facilitate the movement of bacteria in the soil, improving their relationship with plants.

These microbes not only improve soil fertility, but also strengthen the resistance of cereals to drought and disease. In short, they are a natural and powerful alternative to synthetic Chemistry fertilizers.

A combination that makes a difference
In our research group , at the Biodiversity and Environment Institute BIOMA of the University of Navarra, we explore how to combine new generation sustainable fertilizers with the beneficial action of microorganisms. This allows us to get the best of both worlds. We work on the development of biofertilizers that, instead of polluting, promote the development of soil biological activity.

The trials we are currently conducting using microorganisms obtained from inside plants (endophytic microorganisms) indicate that these microscopic companions improve nitrogen and phosphorus uptake, increase resistance to water stress and improve nutritional quality in cereal crops.

In addition, we are currently investigating how to apply this subject of microorganisms together with traditional fertilizers to synergistically maximize the benefits for the farmer and reduce the impact on the environment.

Towards an agricultural revolution
An efficient integration of the two components, fertilizers and microorganisms, could transform the way we grow cereals. Some of the major changes include:

• Greater efficiency in the absorption of nutrients, reducing the need for chemical fertilizers and, therefore, the environmental impacts associated exclusively with the production and transportation process.

• Improved grain quality, with more minerals and compounds beneficial to health, both in humans and farm animals.

• Reduced pollution from fertilization by reducing nitrate leaching and greenhouse gas emissions.

• More resilient crops, able to cope with climate change and disease.

A new way to feed the world
The future of cereals will depend to a large extent on more sustainable agriculture, where fertilizers and microorganisms work in harmony. Science is already moving in this direction, but much remains to be done. It is crucial to continue research, but also to promote and raise awareness of the use of these novel solutions among farmers and the various social actors involved in the fertilizer market (companies, associations, politicians...).

Soil has its own army of microscopic allies. If we learn to work with them, we could be facing an agricultural revolution that benefits both crops and the planet. Will this be the core topic to feed the world without compromising the future? Time (and science) will tell.

This article was originally published in The Conversation. Read the original.