We see the consequences of a long process. The massive contribution of nitrates and nitrites, that is, to synthetic fertilizer, has been identified as responsible for the catastrophe of this coastal lagoon. Algae are also blamed, which in the presence of nutrients grow excessively and reduce the penetration of sunlight and accelerate the decrease in oxygen. Everything points to agriculture.
The keys to understanding why the Mar Menor is in danger
Nitrogen and phosphorus in agriculture
In the world there are 450 million tons of nitrogen that are used for agriculture. Between 1961 and 2019 the use of synthetic fertilizers has grown by 800%, which constitutes an energy and climate problem: we spend more than 5% of the world’s natural gas to extract nitrogen from the atmosphere.
The Agriculture contributes to climate change. Inside of Hydrogen Roadmap in Spain – the Government’s commitment to green hydrogen – it is intended to replace natural gas to produce fertilizers with renewable energy through Haber-Bosch process. For this, nitrogen, potash extracted from the rock and phosphorus extracted from phosphate rock are used. A 2017 study indicates that so far in the 21st century its use has grown by 41%.
In addition to being an energy and climate problem, it is behind the Mar Menor catastrophe. That nitrogen and phosphorus that agriculture uses end up dissipated, partly in the atmosphere and partly in the oceans. This despite the 1992 United Nations convention that protect the oceans.
Among 10.5 and 15.2 million tons of phosphorus they end up in the oceans every year. Nitrogen causes acidity: a pH lower than 7.8 makes the waters unfit for life. Not all acidity in the oceans is related to the carbon cycle; agriculture bears part of the responsibility.
An unsustainable food system
The nitrogen and phosphorus cycle has exceeded planetary limits. In the long term, if trends do not change, we will face a collapse of the global food system in a few decades.
The use of fertilizers has decreased the phosphorus of the soil: “The phosphorus content of our land, after years of cultivation, has decreased considerably. It needs to be replenished. The need for greater use of phosphates and the conservation of our phosphate supplies to future generations is, therefore, a matter of great public concern, “he said. FD Roosevelt in 1938.
The reserves need to be replenished; phosphate supply is a concern for future generations. In recent decades its use has increased by 800%. Today farmers face a phosphorus crisis.
Few elements are involved in life: nitrogen, oxygen, carbon, hydrogen, sulfur, and potassium. In 1974 J. Lovelock and L. Margulis observed that the homeostasis of the Earth was being altered by the use of synthetic nitrogen. It is another proof of the arrival of the Anthropocene.
The result is that this synthetic nitrogen interferes with the natural cycle of organic nitrogen, which in turn explains the need to increase its use. Today we need ten calories of fossil energy to obtain one calorie from food; A century ago, a fossil calorie provided ten of the food.
Agriculture uses synthetic nitrogen, 70% of the world’s water, mineral phosphorus, and biocides. And the result is that the cycle of nitrogen, oxygen and carbon is altered. And one of the consequences is the Mar Menor disaster.
This type of catastrophes that occur in “slow motion” are not perceived: they are lost 75,000 tons of fertile soil annual, 1.3 billion people live in degraded agricultural areas, a 25% of agricultural land shows persistent losses in productivity. Meanwhile, impersonal climate change is being singled out as the culprit.
On the wrong track
Agriculture is responsible for the emission of 6.1 Gt of CO₂ carbon equivalent. These emissions take place especially in spring and fall when tractors remove soil and the sun’s rays kill microorganisms that fix nutrients. Pest control contaminates the entire plant and kills pollinators; but also the fertility that microorganisms provide.
We know that microorganisms are involved in the nitrogen, organic matter, oxygen and carbon cycle and participate in the production of the dimethylsulfide molecule (DMS), key in the plant growth and the formation of clouds and rain.
If plants depleted resources, as expected Justus von Liebig In 1864, our civilization would have disappeared thousands of years ago. The concept of carrying capacity does not explain the cause of the problem, but the consequence. The hunter-gatherer man has an ecological behavior; current agriculture relative to that of the Persian and Egyptian civilizations is quantitative. For Paul Ehrlich, agriculture becomes problematic when it has to fuel population growth.
In 1842, von Liebig founded Scientific Agriculture, which takes a chemical look at plants that use nitrogen. Faced with Malthus’ theses and his prophecies, he finds a solution to the threat of loss of fertility of the earth: to use inorganic nitrogen. In 1920, another chemist, Fritz Haber uses nitrogen directly in agriculture.
Beginnings of agrochemicals
After the First World War, nitrogen began to be used in agriculture, following the theories of Justus von Liebig, to maintain metabolic interactions. Fritz Haber had perfected the technique to apply these fertilizers directly to plants, for which he won the Nobel Prize. The chemical industry manufactured synthetic nitrogen to produce explosives and found, after the war, a use as a fertilizer.
But that civilian use of the war industry in agriculture met with early criticism. Ragnar Berg warned in 1930 that synthetic nitrogen alters the organic nitrogen cycle and foods with synthetic nitrogen do not have the same vitamins, minerals, or trace elements as organic products. Today, exposure to nitrites and nitrates constitutes a health problem.
Nutrient deficient foods
The context matters. It is not only a problem of diets, nor of eating local products in a more sustainable way, nor of eating fresh products, since they are surely grown with nitrites and nitrates. Organic products only guarantee that they have replaced synthetic fertilizers with organic ones, but they do not guarantee that they have recovered the fertility of the soil that allows food to have the appropriate vitamins, amino acids and trace elements.
The worst thing is not that the Haber-Bosch process accounts for a third of the energy of agriculture. We will not be sustainable if we do not question the Justus von Liebig’s postulates, father of agrochemicals.
What happened in the Mar Menor teaches us that a complete transformation of science applied to agriculture is necessary; a science that is barely a few decades old and has produced disasters like they have not seen in thousands of years.
Jordi López Ortega is associate professor, researcher in ecology, energy, health and public policy, Universitat Politècnica de Catalunya – BarcelonaTech