A field experiment was conducted with native soil; sewage sludge (SS); horse manure (HM); chicken manure (CM); vermicompost, organic fertilizer and inorganic fertilizer mixed with the native soil. The soil in each of the seven treatments was also mixed with biochar and planted with eggplant. Eggplant fruits were analyzed for vitamin C, total phenols, and soluble sugars. The number and weight of fruits obtained from inorganic treatments were not significantly different from those obtained from organic fertilizer. Concentrations of total phenols were greatest (28 µg g-1 fresh fruits) in fruits of plants grown in vermicompost mixed with biochar compared to SS and HM amendments. Vitamin C was greatest (265 µg g-1 fresh fruits) in fruits of plants grown in soil amended with biochar compared to all other amendments. Plants grown in CM amended soil were 62% and 67% greater in size compared to plants grown in SS-biochar or vermicompost-biochar amended soil, respectively.
Keywords: Vermicompost; chicken manure; horse manure; sewage sludge; vitamin C.