Fig. 2 Effect of soil amended with four concentrations 12.5, 25, 50, and 100% (full strength) of wheat straw leachate (WSL) and three concentrations (0.25, 0.50, and 1 g) of charcoal on root growth of perennial ryegrass for (A) Experiment 1 and (B) Experiment 2. Soil amended only with charcoal served as the control. Experiments were replicated four times and repeated once