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Revolution in horticulture: Using human excreta as fertilizer!
The research team at HU Berlin is testing the use of fecal compost and urine fertilizer to promote sustainable agriculture.
Revolution in horticulture: Using human excreta as fertilizer!
A research team from the Humboldt University of Berlin (HU) tested the use of human fecal compost and nitrified urine fertilizer on corn plants in a three-year experimental phase. These experiments, carried out in the greenhouse on the university's campus in Berlin-Dahlem, aim to recover valuable nutrients such as phosphorus from human excreta, which are essential for plant growth. Recycling fertilizer from feces could help reduce the artificial production of fertilizers as well as the degradation of phosphorus, such as hu-berlin.de reported.
Currently, fertilizers made from human excretions can only be used for research purposes in Germany. The results of the study showed that fecal compost proved to be an effective phosphorus fertilizer by significantly increasing soluble phosphorus in soil and plants. The urine fertilizer, on the other hand, showed high effectiveness as a nitrogen fertilizer, but achieved lower biomass yields compared to chemical-synthetic nitrogen. These results were published in the specialist journal “Soil Use and Management” and could form the basis for a reassessment of the fertilizer regulation in Germany. The next steps in this research include studying pollutant residues and the climate impacts of the new fertilizers.
Collaborations and applications
The series of tests was carried out in cooperation with the Barnim district works and the Finizio company. The contents of dry toilets that are used at major events and in allotment gardens served as the starting material. To ensure that no pathogens were present, the feces were heated for seven days and then composted. In addition, the fertilizers were used in laboratories, greenhouses and at partner agricultural companies.
Additionally, studies conducted by the Leibniz Institute for Vegetable and Ornamental Crops (IGZ) in Großbeeren found that fertilizer made from human urine can achieve better yields than conventional compost. These field trials with white cabbage show that urine as a fertilizer produces results comparable to organic fertilizers. However, urine fertilizer is currently not approved in Germany, while it is used in countries such as Austria, Liechtenstein and Switzerland. Experts are therefore calling for a change to the fertilizer regulations in order to also allow urine and feces as fertilizer.
Recovery of phosphorus
The recovered use of phosphorus from sewage sludge is becoming increasingly important. The BMEL emphasizes that Germany has to import phosphorus as it has no deposits of its own. Sewage sludge from municipal plants is viewed as an alternative source of phosphorus. Currently, only a small amount of phosphorus is recovered from sewage sludge, but this will be required by law from 2029.
A joint declaration published on August 21, 2024, signed by various ministries and associations, aims to improve the conditions for phosphorus recovery in order to reduce dependence on imports and the impact on the environment. Promoting recovery should also help ensure good harvests and reduce the need for artificial fertilizers.
Overall, current research and policy initiatives show that the use of human waste as fertilizer is not only environmentally friendly, but can also contribute to food security. The next few years will be crucial in creating the legal framework that will enable wider use of these valuable resources.