Effect of Application of Compost and Vermicompost Enriched with Chemical Fertilizer and Manure on Some Biological Indicators of Soil Quality of Basil (Ocimum basilicum) Rhizosphere

Biological indicators are considered soil quality elements، due to their dependence on soil organisms. In order to investigate The effect of compost and vermicompost enriched by chemical fertilizers and manure on soil organic carbon، microbial respiration، and enzymes activity in basil plant''s rhizosphere، a field experiment was conducted as a split-plot design with randomized complete blocks and three replications in 2006. The main plot involved six levels of fertilizer including: 20 and 40 tons of compost enriched، 20 and 40 tons of vermicompost enriched per hectare، chemical fertilizer and control without fertilizer and sub-plot، and period of application (two، three and four years). The results showed that application of compost and vermicompost at all levels increased soil organic carbon (OC) and soil microbial respiration، microbial biomass and urease activity compared to the controls (p<0. 05)، but increasing trend among the treatments was not similar. The maximum amounts of OC، soil microbial respiration and enzyme activity were observed in 40 tons of vermicompost enriched with chemical fertilizer ha-1 with four years of application. In high levels of compost application، the urease activity was decreased.