Organic waste subjected to controlled decomposition processes reduces risks of contamination and acquires agronomic value. The main indicator of quality of a composting product is maturity index, which is determined with different physical, chemical and biological parameters, resulting in a very complex process. Mathematical models have proven to be an efficient tool to evaluate numerous interactions between variables for diagnostic and predictive purposes. The objective was to generate prediction models of maturity index of organic fertilizers produced from organic waste subjected to vermicomposting, semi-composting and composting. A mixture of bovine manure and pine sawdust, with a carbon/nitrogen ratio of 25, was subjected separately to three transformation processes for 183 days. Environmental temperature, organic waste temperature, total nitrogen, organic carbon, pH, carbon/nitrogen ratio, enzymatic activity of urease and phytotoxicity were monitored. A multivariate analysis was performed revealing a great interaction among the variables. Analysis of principal components allowed detecting that the carbon/nitrogen ratio, pH and temperature of organic residues were variables with greatest interaction to predict maturity index. Similarities were observed between vermicomposting and semicomposting, but differences with composting, generating two predictive models. Application of the generated equations allowed estimating the maturity index from 155 days for vermicomposting and semicomposting, and from 183 days for composting. Application of these models will allow predicting optimal time to obtain maturity characteristics in products subjected to transformation processes.

Sánchez‑Rosales R, Hernández‑Rodríguez OA, Jiménez‑Castro JA, Ojeda‑Barrios DL, Guerrero‑Prieto VM, Parra‑Quezada RA (2019). Modelos de predicción del índice de madurez de abonos orgánicos producidos con tres procesos de transformación. ITEA‑Información Técnica Económica Agraria 115(3): 198‑212. https://doi.org/10.12706/itea.2018.033