Liquid organic fertilizers: Local knowledge to promote sustainable agriculture worldwide

Liquid organic fertilizers (LOF) or bioles are liquid bioinput products derived from the fermentation of vegetable and fruit wastes, manure, waste from the dairy industry, and others; their metabolic and microbiological composition varies according to the source of its raw material. Its biostimulant effect has been demonstrated on various crops of agronomic interest in some Latin American countries, such as Costa Rica, where it is produced in an artisanal way. To our knowledge, this is the first literature review of LOF from a technical perspective, showing the stages of their fermentation process, as well as factors that may affect it, and technological tools that will allow us to monitor their quality and safe application in crops. We found that the application of this traditional and local practice has great potential to be projected worldwide; however, more research is needed to standardize its composition and effects according to the type of crop. The use of biotechnological tools for making LOF would allow the determination of their metabolic and microbiological composition and, at the same time, the monitoring of the quality of the product, allowing its safe use in agriculture. Finally, the production and application of LOF within a sustainable agricultural model would favor a circular economy by using organic waste as a raw material, thereby reducing the cost of chemical product consumption.