The annual growth of the world's population demands the growing production of food and basic necessities, which must take place within a context of respect for human dignity and the preservation of nature.

One of the most influential variables in the past and one of the most important in the present and future of the technological and social development is the adequate fertilization of agricultural crops. In the last century, the so-called green revolution was based, among other factors, on the production of highly water-soluble fertilizers that quickly provided nutrients for their assimilation by plants. This approach remains the most widely used approach in fertilizer production today.

However, this approach has major problems of long-term efficacy deadline, as well as high environmental risks. On the one hand, the rapid solubilization of fertilizers by irrigation water or rainwater releases a very high concentration of nutrients that can only be assimilated by plants in a small proportion. The rest of the unassimilated nutrients are lost, blocked in the soil or washed away by water, in the latter case being washed into groundwater, lakes and springs, causing serious ecological and environmental disorders. The collapse of life in the Mar Menor is a good example of this phenomenon. It also has negative effects on the regulation of the uptake and use of nutrients by plants, since there is a large amount of nutrient available, the plants accumulate it (the so-called luxury consumption) and greatly reduce the capacity for its efficient use.

In this context, there is a clear need for a change of approach in the concept of crop fertilization. For this technological evolution, nature can serve as guide and example. Plants have specific modes (mechanisms) for the uptake of nutrients from the soil, which include the segregation of compounds by the root with the capacity to increase the assimilability for the plant of the nutrients present in the fraction of soil that is in direct contact with the root, which is known as rhizosphere. Some of these compounds, besides having a high activity Chemistry that allows the solubilization of soil nutrients, also have the ability to awaken the activity of the microbiota present in the soil at contact with the root. This action is very important, since some of these microorganisms improve the development of the plants by increasing the assimilable nutrients for them and biostimulating vital processes in the plant.

In this context, a possible approach for a new approach to plant fertilization could be the preparation of fertilizers whose capacity to provide assimilable nutrients for plants is not governed by their solubility in water, but by their capacity to react with compounds secreted by plant roots as an expression of their nutritional needs. In this way, the supply of nutrients by the fertilizer would be better adapted to the needs of the plants, thus greatly reducing nutrient losses by immobilization in the soil, or by washing-filtration by the action of water from irrigation or rain.

Our group at research has been working for the last decade on the development and optimization of this approach. Starting with the doctoral thesis of Dr. Javier Erro, professor of the School of Sciences and researcher of Biodiversity and Environment Institute of the University of Navarra, we have continued in the deepening of the mechanisms at molecular and metabolic level that govern what we have called activation of the efficient use of nutrients through the use of special fertilizers. In fact, the patents generated have been implemented at industrial and commercial level, and there are products that base their action on this new principle.

In this context, it is also fundamental to understand how the interaction of plants with microorganisms present in the soil cooperates in the enhancement of plant-specific modes (mechanisms) involved in the efficient use of nutrients. Our programs of study, as well as programs of study carried out by other groups, show that in addition to providing nutrients to plants, some microorganisms are able to enhance the plant's ability to optimize the use of assimilated nutrients in the sense of producing the highest yield per unit of assimilated nutrient. This fact is very relevant and tells us about the complementarity between the use of these special fertilizers, which release nutrients at a rate that suits the needs of the plant, with the application of specific microorganisms that could work together with the fertilizer.

It is true that this new approach requires a change of mentality in the agricultural world, both at the level of fertilizer producers, farmers and legislators, but it constitutes an alternative consistent with a sustainable approach to agriculture while respecting the environment and natural ecosystems.

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José María García-Mina
researcher from Biodiversity and Environment Institute of the University of Navarra.
This article was originally published in The Conversation. Read the original.