If we cross Western Sahara from south to north, parallel to the coast, there are hardly any elevations in the more than 800 kilometers of a route that this journalist had the opportunity to complete a few years ago, following the trail of sub-Saharan migrants. Only at the end, near the capital of the old Spanish province, El Aaiún, do we glimpse white hills inside a huge sealed enclosure. They are mountains of phosphates waiting to board. At this point in the disputed territory, which is now de facto occupied by Morocco, phosphates arrive from the Bucraa mines, a hundred kilometers to the southeast, through the longest conveyor belt in the world, and which continues to operate since Spain built it ago. half a century. In just over thirty years, from 1975 to 2006, it is estimated that at least 40 million tons of the “second most limiting nutrient for agricultural production after nitrogen” have passed through here, as Felipe Bastida defines phosphorus, Senior scientist at the Segura Center for Applied Edaphology and Biology, Cebas-CSIC. “It is an essential nutrient for cultivated plants,” abounds José Luis Moreno, also from Cebas-CSIC. Its use, along with that of the aforementioned nitrogen and also that of potassium, “is integrated into the fertilization plans of any crop.”
Currently, however, phosphorus, unlike the other two ‘macronutrients’ mentioned, is on the way to depletion. Bastida sums it up: “Humanity is now facing a fertilizer crisis: the Sahara mines, which are the main source of phosphate rock, are going to be exhausted in the coming decades.” Two years ago, a group of 40 researchers issued a serious warning collected by the international scientific journal ‘Science Alert’ in an article entitled: “The world could soon run out of a crucial resource and nobody talks about it.” Its lack, “could cause a global catastrophe for the next generation.”
The problem here is greater
It is no small matter for a semi-arid region, where the problem is greater, and with as much agricultural weight as ours. Given “the urgent need to obtain new phosphorous fertilizers that allow us to continue producing efficiently and, in addition, in a sustainable and environmentally friendly way”, reveals Bastida, the Cebas-CSIC, has set to work. Researchers from the Group of Encimology and Bioremediation of Organic Waste Soils from this key agricultural research center in Murcia are leading a project that proposes an alternative source of phosphorus. This project, which will last four years and is financed with some 200,000 euros by the R & D & i program ‘Retos de Investigación’ of the Ministry of Science and Innovation, seeks to «obtain new fertilizers from the recycling of mineral and organic waste with high content of phosphorus ”, explains Felipe Bastida. He is, along with José Luis Moreno, also from Cebas, the principal investigator of this initiative that started last September. «Our purpose is to select and evaluate as fertilizers of P [símbolo del fósforo] certain mineral and organic materials of a residual type and derived from industrial and urban activity, such as bone meal and struvite ”, Moreno specifies. It is, he adds, “waste generated in the meat industries and wastewater treatment plants.”
“Humanity is facing a fertilizer crisis”, warns Felipe Bastida, Cebas researcher
Struvites are mineral compounds generated naturally in purification plants, where they usually clog pipes. The great problem with phosphorus found in struvites, the expert warns, is that “it requires the action of some microorganisms that are responsible for transforming it and making it available for greater agricultural yield”, as is the case with the one that is extracted from bone meal derived from slaughterhouses and also commonly used from phosphoric rocks.
In this context, Bastida relates, what the Cebas-CSIC has proposed to do, in addition to evaluating the role of these residues as sources of phosphates for the soil, is to “identify microorganisms and biochemical processes involved in the” transformation of these residues into new generation cheap fertilizers with the capacity to promote soil fertility, its production and sustainability in Mediterranean agroecosystems ». Moreno points out that this would provide “a solution for the transition from traditional agrosystems to more sustainable ones”, by using fewer natural resources (phosphate rock and water) and degrading the soil and other ecosystems less.
Phosphorus, along with nitrogen and potassium, is integrated into the fertilization plans of any crop
“We are also focused on investigating whether the application of live bacteria (biofertilizers) involved in the cycling of phosphorus in the soil, together with inorganic fertilizers and organic amendments, can improve agricultural production compared to the application of only fertilizers”, review José Siles, postdoctoral researcher who is also participating in the project (a fourth member of the group is Celia García, predoctoral researcher). Surprisingly, despite the warning from the scientific community, the agricultural segment “is not sufficiently aware” of the “phosphorus crisis”, regrets Moreno. In any case, the scientific community does not seem to have worked on such a deep problem either. “We have found little bibliography on studies focused on the evaluation of alternative materials rich in phosphates for soil fertilization,” he acknowledges.
The researcher clarifies that there are other scientific investigations underway in this area, although “focused on purely agronomic aspects.” The novelty of the Cebas-CSIC proposal is the study of soils enriched with the indicated alternative materials with the help of microbiological and biochemical techniques. In this way, “a greater understanding of the processes that release the phosphorus trapped in these materials and that make this element available in the form of phosphates,” which is how it can be absorbed by plants, is achieved. In this way, in addition, advantages can be verified at an agronomic and environmental level “for a more sustainable management of agricultural soils”.
The doctor in Agricultural Chemistry from the University of Murcia Antonio Ruiz, who has also done research at Cebas and now works for the Israeli-Dutch fertilizer company ICL-SF, has just concluded a project on obtaining an organo-fertilizer biofertilizer. sustainable mineral as an alternative to the production of organic waste and the use of fertilizers such as phosphate rock. Struvite is one of the materials he has worked on, “with very good results,” he says.
This study, called Bioforg, is in a way, he adds, “the seed of the national plan project that Felipe has achieved. [Bastida] and José Luis [Moreno]». Ruiz’s current work at ICL-SF, at the moment “the only company in Europe that produces this sustainable phosphorous fertilizer commercially” (referring to struvite), largely exemplifies the interest in seeking a sustainable solution to the problem of phosphorus, as extracted from Ruiz’s account.
Scientists seek to reuse waste from treatment plants and abattoir bones as an alternative
This researcher takes away iron from the “alarmist message about the scarcity of phosphate rock”, although he acknowledges that it will be a problem “for future generations” (experts estimate reserves for between 50 and 100 years). The real problem today, he says, “is accessibility to the resource”, which makes it a matter “of special relevance that needs short-term solutions, especially from a point of view applied to the agricultural sector.”
Ruiz frames these complications in the geopolitical sphere (the mines are located in very specific territories, with the consequent control of supply by a few actors -Morocco, China, Israel and Scandinavian countries-) and in the quality that the material needs to adjust to future regulations. In both cases, the result is a rise in prices, and the consequent search for alternative phosphor materials, “which today are in a very incipient development phase.”
Still inefficient
At the moment, the struvite solution is not yet authorized for agriculture (it is used in gardens and golf courses, for example), although its use in the agricultural sector is ready, according to the “new European Regulation” that it is being prepared, which also authorizes “ashes from the combustion of organic remains: municipal waste, sewage sludge and agro-livestock remains,” says Ruiz. At the moment, he concludes, the technologies that allow the obtaining of secondary phosphates, with which to supply phosphate rocks, are expensive and still inefficient, which implies the need for further research.
In search of a sustainable solution
Carlos García, research professor at Cebas-CSIC, warns of the excessive use that has been made of phosphorus contributions in agriculture, which in a part, “even if it is small”, can leak “and contaminate groundwater creating eutrophication” . In addition, the phosphate rocks from which it has been extracted incorporate pollutants such as cadmium, which has led to limit its use, resulting in an increase in costs and a risk of contamination by leaks. This reality, he adds, “should make us reconsider and try to use the phosphorus that we already have in the soil in a more intelligent way.”
Hence the importance of «new alternatives on the use of existing microorganisms in the soil, with the ability to solubilize phosphorus and make it available to plants, or the use of phosphatase enzymes, capable of hydrolyzing organic phosphorus and converting it to inorganic, also available for the plants”.
They are alternatives for the future, he adds, to which we must pay attention. García explains at this point that the solutions, based on struvite and animal bones, investigated by Cebas-CSIC, “could contribute to a more adequate and rational contribution of phosphorus to soils”. José Siles, a researcher at Cebas, adds that “research in relation to the phosphorus cycle cannot only be focused on the search for new sources, but also on trying to get the maximum possible performance from phosphorous sources that are applied to the soil.”
.