2.2. Pot experiments
In a pot experiment, spinach (Spinach oleracea L.) was
grown as a test crop in a greenhouse. Pumice was sieved
through a 0.5 mm screen and then soil samples were mixed
with 4% and 8% of the pumice (w/w). Ten kilograms of mixed soils were transferred in each polyethylene pot
(diameter: 20 cm, height: 20 cm) with three replications.
Zob-Ahan Steel Company wastewater (a mixed non-toxic
wastewater and urban wastewater) was used for irrigation.
Irrigation with potable water (no added Cd) was done
for an extra set of pots as a control, to study effect of
wastewater on yield. Cadmium chloride, CdCl22H2O, was
used in the irrigation wastewater, before each irrigation,
with the Cd concentration of 10 mg/L. During the experiment,
water in pots was added based on water loss by
weighing it to reach field capacity after 48 hr. The pots
were displaced once in every week.