title: Optimization of Eisenia fetida stocking density for the bioconversion of rock phosphate enriched cow dung-waste paper mixtures.
abstract: Vermitechnology is gaining recognition as an environmental friendly waste management strategy. Its successful implementation requires that the key operational parameters like earthworm stocking density be established for each target waste/waste mixture. One target waste mixture in South Africa is waste paper mixed with cow dung and rock phosphate (RP) for P enrichment. This study sought to establish optimal Eisenia fetida stocking density for maximum P release and rapid bioconversion of RP enriched cow dung-paper waste mixtures. E. fetida stocking densities of 0, 7.5, 12.5, 17.5 and 22.5 g-worms kg(-1) dry weight of cow dung-waste paper mixtures were evaluated. The stocking density of 12.5 g-worms kg(-1) resulted in the highest earthworm growth rate and humification of the RP enriched waste mixture as reflected by a C:N ratio of <12 and a humic acid/fulvic acid ratio of >1.9 in final vermicomposts. A germination test revealed that the resultant vermicompost had no inhibitory effect on the germination of tomato, carrot, and radish. Extractable P increased with stocking density up to 22.5 g-worm kg(-1) feedstock suggesting that for maximum P release from RP enriched wastes a high stocking density should be considered.
authors.affiliation: Department of Agronomy, Faculty of Science and Agriculture, University of Fort Hare, PBX1314, Alice 5700, South Africa. Electronic address: funmifrank2009@gmail.com.
authors.forename: F O
authors.initials: FO
authors.lastname: Unuofin
authors.affiliation: Department of Agronomy, Faculty of Science and Agriculture, University of Fort Hare, PBX1314, Alice 5700, South Africa. Electronic address: pmnkeni@ufh.ac.za.
authors.forename: P N S
authors.initials: PN
authors.lastname: Mnkeni
mesh_terms: D000818:Animals; D001673:Biodegradation, Environmental; D002417:Cattle; D005260:Female; D007220:Industrial Waste / Q000032:analysis*; D008372:Manure / Q000032:analysis*; D009835:Oligochaeta / Q000502:physiology*; D010209:Paper; D010710:Phosphates / Q000378:metabolism*; D011156:Population Density; D012037:Refuse Disposal / Q000379:methods*; D013019:South Africa
chemical_list: D007220:Industrial Waste; D008372:Manure; D010710:Phosphates
keywords: Eisenia fetida; Humification indices; P enrichment; Stocking density; Vermicomposting