Valorization of poultry slaughterhouse waste into fertilizers with designed properties

Climate change, soil erosion, air and water pollution, or problems related to waste management are just some of the many problems in the modern world. Comprehensive solutions are sought to reduce the effects of progressive environmental degradation according to the assumptions of the concept of sustainable development. The paper presents a technological concept that may be a response to these problems. The presented solution assumes full utilization of slaughterhouse waste with the simultaneous recovery of nutrients and the production of functional fertilizing products with designed properties. Four liquid fertilizer formulations with the following composition were prepared: N - 2.30-3.64%, P₂O₅ - 2.18-9.66%, and K₂O - 0.11-4.49%. The manufactured products were characterized by a high sulfur content and the addition of microelements. The tests carried out on plants confirmed their effectiveness similar to commercial mineral fertilizers. An increase in green matter yield of peas by 5 t/ha and maize by 2 t/ha was observed. The lack of microbiological risk associated with their use has been proven. Good efficiency with a simultaneous reduction in production costs resulting from the use of waste materials, as well as limiting the negative impact of poultry farms on the environment, make this solution an attractive alternative to mineral fertilizers, in line with the assumptions of the circular economy.