Researchers from the Higher Technical School of Agricultural Engineering at the University of Seville, together with a group of international experts, have just published a scientific article in which they demonstrate that some soil minerals can convert the nitrogen gases NO + NO2 (NOX) into nitrates by means of visible and ultraviolet radiation. This natural process had not previously been described and demonstrates, according to the data obtained, that solar light seems to be the missing piece in the puzzle of the nitrogen cycle in soil.
"This finding is important, not only because it involves a never-before described natural process, as we have said, but also because the nitrogen in the soil is crucial for global sustainability, as it affects the productivity of the ecosystem and air quality for living organisms, including humans. In addition, nitrogen is connected to the emission of greenhouse gases (GHG) and global warming. It is worth highlighting that NO in soil is the main precursor of N2O, an important GHG", reports the University of Seville teacher and author of the study, Antonio Delgado.
Despite the basic processes in the nitrogen cycle in nature being known for more than a hundred year, in this article, some photocatalytic mechanisms are proposed that were previously unknown. The project shows that solar radiation (especially ultraviolet) can activate soil minerals, so generating reactive types of oxygen (free radicals) that can transform NOx gases into nitrates, and vice versa.
How to maximise the functions of agricultural soil
Parallel to this finding, the research group led by Delgado, has collaborated on the development of a decision-making tool for the improvement of soil function in agriculture. This tool, which is currently available in various languages of the European Union and which will soon be translated into Spanish and adapted to the conditions in Spain, makes it possible for farmers and technicians to choose the best options for maximising each of the five soil functions: productivity, nutrient recycling, water purification and regulation, biodiversity and mitigation of climate change. This tool will also be useful for making policy decisions that affect how current social demand can be met by agriculture. In the tool, in which data regarding soil, climate, and agricultural-exploitation management must be included, the most advisable options for maximising the five soil functions appear.
'Soilnavigator' is one of the most important results of the European project LAND Management: Assessment, Research, Knowledge base (LANDMARK). Within this project, a scientific framework has been drawn up for legislators that can serve as a base for the preparation of valid regulations for all of Europe. Twenty-two institutions from 14 European countries, as well as Switzerland, Brazil and China, participated in the project.
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The article was available online from 2nd November 2019, but the printed version just came out on 1st February 2020.
Journal
The Science of The Total Environment