Fig. 3 Effect of soil amended with four concentrations 12.5, 25, 50, and 100% (full strength) of wheat straw leachate (WSL) and five concentrations (0, 0.25, 0.50, 0.75, and 1 mM) of N fertilizer on root growth of perennial ryegrass for (A) Experiment 1 and (B) Experiment 2. Soil amended with 0 mM of N fertilizer served as the control. Experiments were replicated four times and repeated once