Figure 4.

Microbial respiration rate fitted to the exponential first order decay function (Mineralized C = C₀ e^−kt) and derived parameters (C₀, biological available C; k, turnover constant rate; C₀K, initial potential rate of C mineralization) determined on soil treated with Mentha × piperita L. essential oil (EO) applied by irrigation. Treatments were: Cw (no Fitoil and EO application), Cf (0.03 μL Fitoil g⁻¹ of soil and no EO application), T1 (0.03 μL Fitoil g⁻¹ of soil and 0.31 μL EO g⁻¹ of soil), T2 (0.03 μL Fitoil g⁻¹ of soil and 0.67 μL EO g⁻¹ of soil), and T3 (0.03 μL Fitoil g⁻¹ of soil and 0.93 μL EO g⁻¹ of soil). Reported results are means (n = 4). Bars indicate the standard deviations. Lower case letters indicate significant differences among treatments.