The inoculum band consisted of 75 g living soil removed
from the long axis of a soil core plus 75 g sterile soil from each of
the other inoculum sources. This was done to equalize differences
in soil fertility among the inoculum treatments (Johnson, 1993).
Sterile soil for the inoculum bands was prepared by placing soil in
plastic bags and heating them to 80 ◦C for 3min in a microwave
oven (Ferris, 1984). This method has been shown to have minimal
impact on soil nutrient content yet still eradicate AM fungal
propagules. Non-mycorrhizal (−AM) controls were created using
only sterilized soil in the inoculum band.