Réparer la rupture métabolique de l’Anthropocène à travers une économie circulaire des excréta humains

Food and agriculture are old subjects for all human societies. At first glance, the questions they raise seem uninteresting and anachronistic in the light of certain contemporary challenges such as the conquest of space, artificial intelligence, blockchain, energy and the extension of life expectancy... Yet the future of our species is at stake when it comes to our food. The foundations of the agricultural and food crisis we are experiencing today and which will worsen tomorrow stem from a metabolic breakdown. This metabolic breakdown is based on a simple observation that has been masked by several centuries of civilisation: some of the nutrients taken from the soil to produce our food do not return to the soil because of a disconnection between the places where our food is produced and the places where it is consumed and excreted. The soils in the countryside that produce our food are irreparably impoverished because they do not recover the macronutrients contained in human excreta, which are discharged into the sewers and treatment plants of towns and cities. In these conditions, only artificial fertilisers can maintain their fertility. This artificial looping of the nutrient cycle through synthetic fertilisers means a huge energy outlay and huge greenhouse gas emissions. A more logical and much less impactful solution would be to complete the nutrient cycle using a circular economy of human excreta.