One half of the experimental soil was autoclaved at
121 °C for 2 h in order to eliminate the native mycorrhizal
fungi and then air-dried. Pots were filled with
3.1 kg of either non-autoclaved or autoclaved soil.
Before the seeds were sown, the following mineral
nutrients were added to each pot as concentrated solutions
and uniformly incorporated into the soil my
mixing thorougly (per kg air-dry soil): 300 mg N in
the form of Ca(NO3)2 4H2O; 25 mg S in the form of
K2SO4; 15 mg (low), 60 mg (medium) or 180 mg (high)
P in the form of Ca(H2PO4)2; and 0.2 mg (low) or
5.0 mg (high) Zn in the form of ZnSO4 7H2O. The soil
experiment had a fully factorial design with 2 sets of 5
pot replicates per treatment, and the pots were completely
randomized in the greenhouse. Seven plants were
grown in each pot. Throughout the experiment, the pots
were watered daily with deionized water. The pots were
supplied with additional 100 mg N in the form of
Ca(NO3)2 4H2O 52 days after sowing (DAS).