The world's growing population demands ever-increasing crop production. However, the fertilizers required to meet this demand have environmental impacts at different levels, from the employment of finite raw materials and the use of mining, to unsustainable manufacturing processes, to inefficient products that increase environmental pollution.

For decades, the agricultural Philosophy has relied on excess nutrient inputs to the field. As much of the nutrients are lost along the way, it becomes necessary to add significant extra to meet the demands of the crop. This has generated, beyond cost overruns, a considerable environmental footprint, both in the air and in the water and soil, making the latter less and less fertile.

Towards a sustainable strategy
In this context, at the group of Biology and Agricultural Chemistry (BACH) of the BIOMA Institute of the University of Navarra, we carry out research to optimize natural resources, both soil and crops, and to develop more efficient and sustainable alternative strategies with the least environmental impact.

There are two approaches to any problem: the one that starts from oneself and the one that comes from the observed reality. The history of science teaches us that the approaches that emerge from the theories and hypotheses of the human mind trying to impose that model on reality lead to erroneous paradigms.

Therefore, in our research we try to put on internship the second approach, based on the observation of reality. First of all, we seek to study in depth the strategies of plants to absorb and use nutrients. In the same way, we delve into the Biochemistry that occurs in the soil. We thus start from a non-invasive approach to reality in order to learn from it and from there design solutions.

From the study to the final product
We investigate and deepen the knowledge soil-plant system at all levels: ionomic, metabolomic, microbiological and genomic.

The study of plants shows us sample that they release organic acids through their roots when they need nutrients. It also reveals that when they have to activate these mechanisms of food intake, they take advantage of and squeeze much more of the absorbed nutrients.

The study of the soil reveals the existence of a special organic subject called humic acid with interesting biostimulant properties for plants, as well as the presence of soil microorganisms that can associate symbiotically with the plant to improve its growth.

Thus, in our research we have designed formulations such as the following:

• Humic acid-based biostimulants to improve agricultural production.

• Fertilizers with humic acids that are released only when the plants release organic acids. In other words, fertilizers that are not lost along the way (they do not pollute) and are taken only when the plant needs them.

• Fertilizers with the same solubility dynamics, but starting from by-products, in line with circular strategies. An example is the fertilizer use of the mineral struvite generated in wastewater treatment plants.

• Microbiological applications, such as certain root-inhabiting fungi that stimulate the development of the plant, especially in stressful situations.

Finally, in order to improve the whole process of manufacturing and use of fertilizers to minimize their impact, we have developed:

• A decontaminant that irreversibly removes organic and inorganic products in situ in the soil. To this end, we use circular strategies including in the decontaminant by-products from the production of magnesium oxide - with application in animal feed and agriculture - from magnesites.

• A method of manufacturing fertilizers without aqueous media and with higher yields, by mechanoactivation. In this system, solid reagents are mixed in a ball mill, the friction of which generates the heat necessary for the reaction to take place.

• A design of artificial soils using by-products to backfill and restore the mining hill. This involves mixing compost, mining by-products and sand to simulate the texture and organic content of the soil.

We can summarize the lines of our research Philosophy in a respectful approach to what is studied -from the contemplation of the natural resources of the environment- to, through interdisciplinary deepening at different levels of study, consider the impacts of the whole process and, from there, land on the application internship viable and sustainable.

The future of fertilizers rests on a smaller, more efficient and sustainable design and application. And for that, we need a quality, in-depth research to provide solutions to achieve this.

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Javier Erro researcher and Professor partner. Biology and Chemistry Agricultural, University of Navarra 10.10.2024