The University of La Laguna has extensive experience in the study of soils (Pedology) and in the development of projects aimed at halting and mitigating the effects of desertification. The research group \u201cSoil and water resources<\/a>\u201d, directed by the emeritus professor of the Department of Animal Biology, Soil Science and Geology Marisa Tejedor<\/a>, He has dedicated decades to the research and analysis of island soils, contributing unprecedented knowledge in this field. One of his main concerns has been to halt the slow but inexorable advance of arid zones due to human activity.<\/p>\n Marisa Tejedor.<\/p><\/div>\n Desertification and desertization, which are not the same thing<\/strong><\/p>\n These two concepts are often used interchangeably, but they are not synonymous. The professor emerita clarifies this because \u201cthere is a lot of confusion.\u201d Thus, desertization is a natural process, while in desertification, \u201cthe hand of humankind is behind it,\u201d a crucial distinction. Since desertization is a phenomenon unrelated to human activity, little can be done about it, whereas it is possible to take action regarding its semantic counterpart, desertification. For this reason, to try to curb human impact on this process, the international community ratified the treaty in 1994, which this year celebrates its thirtieth anniversary and aims to achieve land degradation neutrality by 2030, something that directly affects some 500 million people.<\/p>\n The figures leave no doubt about the seriousness of the problem and its global relevance. As the professor explains, 461% of the Earth's surface corresponds to arid, semi-arid, and dry sub-humid zones. These areas are those where the ratio between annual precipitation and potential evapotranspiration is between 0.05 and 0.65. In other words, places where it rains little and it is very hot. According to studies carried out by the "Soil and Water Resources" group, 80% of the surface area of the Canary Islands is at serious risk of desertification. "Not all the islands are at the same risk of undergoing this process; there are clear differences between the eastern and western islands." This would include all of Lanzarote and Fuerteventura, a large part of Gran Canaria, areas of La Gomera, and southern Tenerife. The Iberian Peninsula also has very arid zones located east of Andalusia and south of the Valencian Community.<\/p>\n Several studies by the Ministry for Ecological Transition and the Demographic Challenge estimate that 75% of Spain's land area is at risk of desertification, meaning that, broadly speaking, it affects the entire country except for the Cantabrian coast and part of the Pyrenees. If we look at a map of Spain's average rainfall alongside one of aridity, we see that they almost perfectly match. "It's a matter of balance, between the rain that falls and the rain that evaporates," Tejedor points out.<\/p>\n The importance of irrigation<\/strong><\/p>\n Since human activity is behind desertification, not everything depends on the amount of rain; certain actions caused by people accelerate the aridity of the land, such as deforestation, fires, overgrazing, intensive agriculture, abandonment of traditional crops, or inadequate irrigation management.<\/p>\n Interestingly, the management of irrigation systems is behind much of the soil degradation on the islands. It seems contradictory that a place can become arid as a consequence of irrigation, even if it's done poorly. But reality is stubborn, and the studies that have been carried out Carmen Jim\u00e9nez<\/a>, Professor [Name], a tenured professor in the Department of Animal Biology, Soil Science, and Geology, attests to this. In a context where the only source of water supply has to come from \u201calternative\u201d resources such as treated wastewater, and where natural water resources cannot satisfy the needs of the fields, ensuring water quality is fundamental. Improper treatment of reclaimed water could sterilize the soil and turn a solution into a major problem.<\/p>\n One of the lines of research the professor has been working on for many years is characterizing desalinated and reclaimed water. They have measured the impact of using this water, paying close attention to the effect of salts, which is a symptom of potentially low water quality. Their work in Lanzarote, Fuerteventura, and Tenerife shows an improvement in water quality, undoubtedly resulting from the technological development of wastewater treatment and desalination plants. The researcher has been able to verify this firsthand. "I remember when we started working, the water smelled bad, and the farmers, understandably, wanted nothing to do with it." But what do we do about the salinity?<\/p>\n On islands like Lanzarote and Fuerteventura, most of the water comes from seawater, "maintaining high levels of chlorides and sodium," which is causing the soils to become salinized "at an alarming rate." Irrigation management, Jim\u00e9nez points out, is also a crucial factor, as soil degradation varies significantly depending on whether drip irrigation (the least harmful) or flood irrigation (the most harmful). "Fortunately, almost all crops now use drip irrigation." Regarding the quality of water from wastewater treatment and desalination plants, Marisa Tejedor is emphatic: "That is our future. Either we improve the quality of desalinated and reclaimed water, or agriculture in the Canary Islands will have no future. We are obligated to use that water.".<\/p>\n Carmen Jim\u00e9nez.<\/p><\/div>\n Traditional agriculture to the rescue<\/strong><\/p>\n Before desalination plants, before wastewater treatment plants, farmers were already cultivating crops in the Canary Islands. Faced with the impossibility of using any water source other than rainwater, they learned to squeeze every drop of it, becoming experts in resource management, and their legacy is now being rediscovered. How to improve water collection and increase soil moisture? The solution lay in the volcano. The islands' ancient farmers learned that spreading volcanic ash (jable, pic\u00f3n, or zahorra) over their crops improved yields.<\/p>\n Jim\u00e9nez gives the example of La Geria<\/a>, In Lanzarote, a place dedicated to grape cultivation that produces highly prized wines worldwide. This system "is able to make the most of the little rain that arrives, prevents erosion problems, washes the soil, and controls the surface temperature." Another traditional use for water collection is... gavias<\/a>, wall systems that are used to take advantage of the water from the runoff of ravines.<\/p>\n The researchers have been able to experimentally verify the benefits of this sand-surfacing system. On the island of Fuerteventura, they covered soils that were \u201ccompletely degraded, absolutely salinized, and unsuitable for cultivation\u201d with volcanic volcanic ash. After adding this layer of volcanic material, a few centimeters thick, they waited a year and analyzed the soil for changes. After only 12 months, \u201cthe salinity level in the first 30 centimeters had already decreased sufficiently to allow for cultivation, in just one year.\u201d According to them, the local government has taken note, and these \u201csandy areas\u201d are currently being restored to recover the agricultural legacy of our ancestors.<\/p>\n The abandonment of agriculture is one of the catalysts for desertification. The historical exodus from the countryside to the tourism and service sectors has turned areas that were once cultivated into wastelands. Plants, whatever their type, protect the soil. The worst thing that can happen to a surface is to become barren and exposed to the elements. "Any soil cover is welcome." In this regard, experiments have been conducted with the introduction of plants capable of growing in degraded land and which are also of interest for biodiesel production.<\/p>\n The problem of forest fires<\/strong><\/p>\n To the lack of rain, increased soil salinity and abandonment of agriculture, we must add forest fires, although it is very likely that all these factors feed into each other. Jonay Neris<\/a> He is an assistant professor in the Department of Animal Biology, Soil Science and Geology and has dedicated a good part of his career to investigating the effects of forest fires on soils.<\/p>\n![\"Marisa](\"https:\/\/www.ull.es\/portal\/noticias\/wp-content\/uploads\/sites\/2\/2026\/10\/Edafologia-Marisa-Tejedor-07-200x300.jpg\")
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