Bioconversion of agro-industrial wastes: Combined compost and vermicompost processes using Eisenia fetida for stabilization of poultry litter

CAROLINA MASIN; EMILIA FERNÁNDEZ; LESCANO, MAIA RAQUEL; ZALAZAR, CRISTINA SUSANA

International Journal of Recycling of Organic Waste in Agriculture

Islamic Azad University-Isfahan Branch

Año: 2020 vol. 9 p. 107 - 118

2195-3228

AbstractPurposeA combined treatment ofcomposting and vermicomposting of poultry litter (PL), rice hulls (RH) and/or eucalyptus sawdust (ES) wascarried out in order to obtain a high-quality organic fertilizer and avoid theenvironmental problems associated with the use of raw poultry manure and freshagricultural waste materials.MethodsThree composting mixtureswere made at volume proportions: 1:3 RH/PL (M1); 1:2 ES/PL (M2) and 0.5:1:2RH/ES/PL (M3). Composting (120 days) followed by vermicomposting (90 days) using earthworms (Eisenia fetida) were conducted during the autumn-winterseason, outdoors and sheltered. Moisture content was kept at 60-70%. Physicochemical (pH,electrical conductivity, lignin, total carbon and nitrogen, organic matter, ammoniumand specific cations), total microbial activity (fluorescein diacetate hydrolysis)and microbiological parameters were recorded throughout both processes. Phytotoxicity tests were lastly performed by means of Lactuca sativa, L. seed germination, tocompare the quality of the organic fertilizers obtained. ResultsAsequential compost-vermicompost process enhanced the properties of the finalproducts. Particularly, electrical conductivity was markedlylower in all vermicomposts (1.81-2.28 mS cm-1)and within the values recommendedfor the growth of sensitive plants; microbial activity reached 187.1-203.8 µg FDAgsoil-1 h-1. Germination Index values in vermicomposts were greater than 60%,indicating the high quality of the products obtained, being the mixture0.5RH:1ES:2PL the one which showed better quality and higher maturation degree. ConclusionThe systemthat combines both processes (composting+vermicomposting) was effective to produce a stabilized organic fertilizer from poultry litter withother waste organic materials.