Comparison of three systems of decomposition of agricultural residues for the production of organic fertilizers

Rocío Sánchez-Rosales1, Adriana Hernández-Rodríguez1*, Dámaris Ojeda-Barrios1, Loreto Robles-Hernández1, Ana Cecilia González-Franco1, and Rafael Parra-Quezada1
Organic wastes (OW) of diverse nature must be subjected to controlled decomposition processes to avoid risks of contamination and obtain products useful for agriculture. The objective of the present study was to compare over time physical, chemical and enzymatic parameters of OW transformed as vermicomposting (VC), semicomposting (SC) and composting (CP) for elaboration of organic fertilizers. A mixture of bovine manure and sawdust was subjected to each of three systems for 183 d. Temperature, total N (Nt), organic C (OC), C/N ratio, pH, enzymatic urease activity (EUA), germination index (GI) and electrical conductivity (EC) were measured throughout the time of study. The variables evaluated showed significant differences between time and treatment. The temperature ranged between 20 and 34 °C in VC and SC, while in CP between 20 and 61 °C. All three systems reduced the C/N ratio to less than 15/1. The CP product had higher pH, EC, and EUA values than both VC and SC. The VC product had the highest GI values. All the products obtained at 183 d were within the parameters to be considered as organic fertilizers, but the SC product transformed into an organic fertilizer fastest and had least water usage.
Keywords: Compost, semicomposting, vermicomposting.
1Universidad Autónoma de Chihuahua, Avenida Universidad y Pascual Orozco s/n, Universidad, 31110 Chihuahua, México.
*Corresponding author (aernande@uach.mx).