Experimental Design and Sampling

The experiment, started in February 2016, was carried out in a greenhouse in 100 × 50 × 45 cm plastic containers. Three treatments were set up: iron tailing sand + soil (T0), iron tailing sand + soil + P. giganteum (T1), and iron tailing sand + soil + bio-matrix pot + P. giganteum (T2). Approximately 54 kg of iron tailing sand was placed into the container, and a hole the size of the bio-matrix pot was carved in the middle at the top (Figure 1). In T0 and T1, 6.5 kg of soil was placed into the hole; in T2, the soil was placed into the bio-matrix pot that was inserted into the hole. In T1 and T2, one P. giganteum seedling was transplanted into the soil. The containers were irrigated with distilled water.

Design of the treatments: (1) soil, (2) iron tailing sand, (3) Pennisetum giganteum seedling, (4) bio-matrix pot, and (5) sampling spot.

Iron tailing sand samples from three containers per treatment were collected at 90, 180, and 360 days (Figure 1). The pH and OM, AN, AP, and AK contents were determined as described previously (Siddiqi and Glass, 1981). The plants were harvested at 360 days, and the shoot and root biomasses were measured after drying at 60°C to constant weight.